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Extensions prefixed with "Su" won't corrupt the workaround in many
cases. The only exception is when the first multi-letter extension in the
ISA string begins with "Su" and is not prefixed with an underscore.
For instance, following ISA string can confuse this QEMU workaround.
* "rv64imacsuclic" (RV64I + M + A + C + "Suclic")
However, this case is very unlikely because extensions prefixed by either
"Z", "Sm" or "Ss" will most likely precede first.
For instance, the "Suclic" extension (draft as of now) will be placed after
related "Smclic" and "Ssclic" extensions. It's also highly likely that
other unprivileged extensions like "Zba" will precede.
It's also possible to suppress the issue in the QEMU workaround with an
underscore. Following ISA string won't confuse the QEMU workaround.
* "rv64imac_suclic" (RV64I + M + A + C + delimited "Suclic")
This fix is to tell kernel developers the nature of this workaround
precisely. There are some "Su*" extensions to be ratified but don't worry
about this workaround too much.
This commit comes with other minor editorial fixes (for minor wording and
spacing issues, without changing the meaning).
Signed-off-by: Tsukasa OI <research_trasio@irq.a4lg.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/8a127608cf6194a6d288289f2520bd1744b81437.1690350252.git.research_trasio@irq.a4lg.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
When Zicboz is present, enable its instruction (cbo.zero) in
usermode by setting its respective senvcfg bit. We don't bother
trying to set this bit per-task, which would also require an
interface for tasks to request enabling and/or disabling. Instead,
permanently set the bit for each hart which has the extension when
bringing it online.
This patch also introduces riscv_cpu_has_extension_[un]likely()
functions to check a specific hart's ISA bitmap for extensions.
Prior to checking the specific hart's bitmap in these functions
we try the bitmap which represents the LCD of extensions, but only
when we know it will use its optimized, alternatives path by gating
its call on CONFIG_RISCV_ALTERNATIVE. When alternatives are used, the
compiler ensures that the invocation of the LCD search becomes a
constant true or false. When it's true, even the new functions will
completely vanish from their callsites. OTOH, when the LCD check is
false, we need to do a search of the hart's ISA bitmap. Had we also
checked the LCD bitmap without the use of alternatives, then we would
have ended up with two bitmap searches instead of one.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230918131518.56803-10-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
commit c818fea83de4 ("riscv: say disabling zicbom if no or bad
riscv,cbom-block-size found") improved the error messages for
zicbom but zicboz was missed since its patches were in flight
at the same time. Get 'em now.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230918131518.56803-9-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Evan Green <evan@rivosinc.com> says:
The current setting for the hwprobe bit indicating misaligned access
speed is controlled by a vendor-specific feature probe function. This is
essentially a per-SoC table we have to maintain on behalf of each vendor
going forward. Let's convert that instead to something we detect at
runtime.
We have two assembly routines at the heart of our probe: one that
does a bunch of word-sized accesses (without aligning its input buffer),
and the other that does byte accesses. If we can move a larger number of
bytes using misaligned word accesses than we can with the same amount of
time doing byte accesses, then we can declare misaligned accesses as
"fast".
The tradeoff of reducing this maintenance burden is boot time. We spend
4-6 jiffies per core doing this measurement (0-2 on jiffie edge
alignment, and 4 on measurement). The timing loop was based on
raid6_choose_gen(), which uses (16+1)*N jiffies (where N is the number
of algorithms). By taking only the fastest iteration out of all
attempts for use in the comparison, variance between runs is very low.
On my THead C906, it looks like this:
[ 0.047563] cpu0: Ratio of byte access time to unaligned word access is 4.34, unaligned accesses are fast
Several others have chimed in with results on slow machines with the
older algorithm, which took all runs into account, including noise like
interrupts. Even with this variation, results indicate that in all cases
(fast, slow, and emulated) the measured numbers are nowhere near each
other (always multiple factors away).
* b4-shazam-merge:
RISC-V: alternative: Remove feature_probe_func
RISC-V: Probe for unaligned access speed
Link: https://lore.kernel.org/r/20230818194136.4084400-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Rather than deferring unaligned access speed determinations to a vendor
function, let's probe them and find out how fast they are. If we
determine that an unaligned word access is faster than N byte accesses,
mark the hardware's unaligned access as "fast". Otherwise, we mark
accesses as slow.
The algorithm itself runs for a fixed amount of jiffies. Within each
iteration it attempts to time a single loop, and then keeps only the best
(fastest) loop it saw. This algorithm was found to have lower variance from
run to run than my first attempt, which counted the total number of
iterations that could be done in that fixed amount of jiffies. By taking
only the best iteration in the loop, assuming at least one loop wasn't
perturbed by an interrupt, we eliminate the effects of interrupts and
other "warm up" factors like branch prediction. The only downside is it
depends on having an rdtime granular and accurate enough to measure a
single copy. If we ever manage to complete a loop in 0 rdtime ticks, we
leave the unaligned setting at UNKNOWN.
There is a slight change in user-visible behavior here. Previously, all
boards except the THead C906 reported misaligned access speed of
UNKNOWN. C906 reported FAST. With this change, since we're now measuring
misaligned access speed on each hart, all RISC-V systems will have this
key set as either FAST or SLOW.
Currently, we don't have a way to confidently measure the difference between
SLOW and EMULATED, so we label anything not fast as SLOW. This will
mislabel some systems that are actually EMULATED as SLOW. When we get
support for delegating misaligned access traps to the kernel (as opposed
to the firmware quietly handling it), we can explicitly test in Linux to
see if unaligned accesses trap. Those systems will start to report
EMULATED, though older (today's) systems without that new SBI mechanism
will continue to report SLOW.
I've updated the documentation for those hwprobe values to reflect
this, specifically: SLOW may or may not be emulated by software, and FAST
represents means being faster than equivalent byte accesses. The change
in documentation is accurate with respect to both the former and current
behavior.
Signed-off-by: Evan Green <evan@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230818194136.4084400-2-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
* Support for the new "riscv,isa-extensions" and "riscv,isa-base" device
tree interfaces for probing extensions.
* Support for userspace access to the performance counters.
* Support for more instructions in kprobes.
* Crash kernels can be allocated above 4GiB.
* Support for KCFI.
* Support for ELFs in !MMU configurations.
* ARCH_KMALLOC_MINALIGN has been reduced to 8.
* mmap() defaults to sv48-sized addresses, with longer addresses hidden
behind a hint (similar to Arm and Intel).
* Also various fixes and cleanups.
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Merge tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
- Support for the new "riscv,isa-extensions" and "riscv,isa-base"
device tree interfaces for probing extensions
- Support for userspace access to the performance counters
- Support for more instructions in kprobes
- Crash kernels can be allocated above 4GiB
- Support for KCFI
- Support for ELFs in !MMU configurations
- ARCH_KMALLOC_MINALIGN has been reduced to 8
- mmap() defaults to sv48-sized addresses, with longer addresses hidden
behind a hint (similar to Arm and Intel)
- Also various fixes and cleanups
* tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
lib/Kconfig.debug: Restrict DEBUG_INFO_SPLIT for RISC-V
riscv: support PREEMPT_DYNAMIC with static keys
riscv: Move create_tmp_mapping() to init sections
riscv: Mark KASAN tmp* page tables variables as static
riscv: mm: use bitmap_zero() API
riscv: enable DEBUG_FORCE_FUNCTION_ALIGN_64B
riscv: remove redundant mv instructions
RISC-V: mm: Document mmap changes
RISC-V: mm: Update pgtable comment documentation
RISC-V: mm: Add tests for RISC-V mm
RISC-V: mm: Restrict address space for sv39,sv48,sv57
riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent
riscv: allow kmalloc() caches aligned to the smallest value
riscv: support the elf-fdpic binfmt loader
binfmt_elf_fdpic: support 64-bit systems
riscv: Allow CONFIG_CFI_CLANG to be selected
riscv/purgatory: Disable CFI
riscv: Add CFI error handling
riscv: Add ftrace_stub_graph
riscv: Add types to indirectly called assembly functions
...
These are the remaining few clean-ups of DT related includes which
didn't get applied to subsystem trees.
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Merge tag 'devicetree-header-cleanups-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull devicetree include cleanups from Rob Herring:
"These are the remaining few clean-ups of DT related includes which
didn't get applied to subsystem trees"
* tag 'devicetree-header-cleanups-for-6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
ipmi: Explicitly include correct DT includes
tpm: Explicitly include correct DT includes
lib/genalloc: Explicitly include correct DT includes
parport: Explicitly include correct DT includes
sbus: Explicitly include correct DT includes
mux: Explicitly include correct DT includes
macintosh: Explicitly include correct DT includes
hte: Explicitly include correct DT includes
EDAC: Explicitly include correct DT includes
clocksource: Explicitly include correct DT includes
sparc: Explicitly include correct DT includes
riscv: Explicitly include correct DT includes
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it was merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Link: https://lore.kernel.org/r/20230714174043.4040561-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
As it says on the tin, provide Kconfig option to control parsing the
"riscv,isa" devicetree property. If either option is used, the kernel
will fall back to parsing "riscv,isa", where "riscv,isa-base" and
"riscv,isa-extensions" are not present.
The Kconfig options are set up so that the default kernel configuration
will enable the fallback path, without needing the commandline option.
Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Suggested-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-aviator-plausibly-a35662485c2c@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add support for parsing the new riscv,isa-extensions property in
riscv_fill_hwcap(), by means of a new "property" member of the
riscv_isa_ext_data struct. For now, this shadows the name of the
extension for all users, however this may not be the case for all
extensions, based on how the dt-binding is written.
For the sake of backwards compatibility, fall back to the old scheme
if the new properties are not detected. For now, just inform, rather
than warn, when that happens.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-vocation-profane-39a74b3c2649@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Before adding more complexity to it, split riscv_fill_hwcap() into 3
distinct sections:
- riscv_fill_hwcap() still is the top level function, into which the
additional complexity will be added.
- riscv_fill_hwcap_from_isa_string() handles getting the information
from the riscv,isa/ACPI equivalent across harts & the various quirks
there
- riscv_parse_isa_string() does what it says on the tin.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-daylight-puritan-37aeb41a4d9b@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
So that riscv_fill_hwcap() can use riscv_isa_ext to probe for single
letter extensions, add them to it.
As a result, what gets spat out in /proc/cpuinfo will become borked, as
single letter extensions will be printed as part of the base extensions
and while printing from riscv_isa_arr. Take the opportunity to unify the
printing of the isa string, using the new member of riscv_isa_ext_data
in the process.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-despite-bright-de00ac888cc7@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
In riscv_fill_hwcap() riscv_isa_ext array can be looped over, rather
than duplicating the list of extensions with individual
SET_ISA_EXT_MAP() usage. While at it, drop the statement-of-the-obvious
comments from the struct, rename uprop to something more suitable for
its new use & constify the members.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-dastardly-affiliate-4cf819dccde2@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
To facilitate using one struct to define extensions, rather than having
several, shunt isa_ext_arr to cpufeature.c, where it will be used for
probing extension presence also.
As that scope of the array as widened, prefix it with riscv & drop the
type from the variable name.
Since the new array is const, print_isa() needs a wee bit of cleanup to
avoid complaints about losing the const qualifier.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-spirits-upside-a2c61c65fd5a@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
ACPI ISA strings are based on a specification after Zicsr and Zifencei
were split out of I, so we shouldn't be treating them as part of I. We
haven't release an ACPI-based kernel yet, so we don't need to worry
about compatibility with the old ISA strings.
Fixes: 07edc32779e3 ("RISC-V: always report presence of extensions formerly part of the base ISA")
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20230711224600.10879-1-palmer@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Conor Dooley <conor@kernel.org> says:
From: Conor Dooley <conor.dooley@microchip.com>
Here are some bits that were discussed with Drew on the "should we
allow caps" threads that I have now created patches for:
- splitting of riscv_of_processor_hartid() into two distinct functions,
one for use purely during early boot, prior to the establishment of
the possible-cpus mask & another to fit the other current use-cases
- that then allows us to then completely skip some validation of the
hartid in the parser
- the biggest diff in the series is a rework of the comments in the
parser, as I have mostly found the existing (sparse) ones to not be
all that helpful whenever I have to go back and look at it
- from writing the comments, I found a conditional doing a bit of a
dance that I found counter-intuitive, so I've had a go at making that
match what I would expect a little better
- `i` implies 4 other extensions, so add them as extensions and set
them for the craic. Sure why not like...
* b4-shazam-merge:
RISC-V: always report presence of extensions formerly part of the base ISA
dt-bindings: riscv: explicitly mention assumption of Zicntr & Zihpm support
RISC-V: remove decrement/increment dance in ISA string parser
RISC-V: rework comments in ISA string parser
RISC-V: validate riscv,isa at boot, not during ISA string parsing
RISC-V: split early & late of_node to hartid mapping
RISC-V: simplify register width check in ISA string parsing
Link: https://lore.kernel.org/r/20230607-audacity-overhaul-82bb867a825f@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Of these four extensions, two were part of the base ISA when the port was
written and are required by the kernel. The other two are implied when
`i` is in riscv,isa on DT systems.
There's not much that userspace can do with this extra information, but
there is no harm in reporting an ISA string that closer resembles the
current versions of the specifications either.
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230607-nest-collision-5796b6be8be6@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
While expanding on the comments in the ISA string parsing code, I
noticed that the conditional decrement of `isa` at the end of the loop
was a bit odd.
The parsing code expects that at the start of the for loop, `isa` will
point to the first character of the next unparsed extension.
However, depending on what the next extension is, this may not be true.
Unless the next extension is a multi-letter extension preceded by an
underscore, `isa` will either point to the string's null-terminator or
to the first character of the next extension, once the switch statement
has been evaluated.
Obviously incrementing `isa` at the end of the loop could cause it to
increment past the null terminator or miss a single letter extension, so
`isa` is conditionally decremented, just so that the loop can increment
it again.
It's easier to understand the code if, instead of this decrement +
increment dance, we instead use a while loop & rely on the handling of
individual extension types to leave `isa` pointing to the first
character of the next extension.
As already mentioned, this won't be the case where the following
extension is multi-letter & preceded by an underscore. To handle that,
invert the check and increment rather than decrement.
Hopefully this eliminates a "huh?!?" moment the next time somebody tries
to understand this code.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20230607-estate-left-f20faabefb89@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
I have found these comments to not be at all helpful whenever I look at
the parser. Further, the comments in the default case (single letter
parser) are not quite right either.
Group the comments into a larger one at the start of each case, that
attempts to explain things at a higher level.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230607-headpiece-tannery-83ed5cc4856a@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Since riscv_fill_hwcap() now only iterates over possible cpus, the
basic validation of whether riscv,isa contains "rv<width>" can be moved
to riscv_early_of_processor_hartid().
Further, "ima" support is required by the kernel, so reject any CPU not
fitting the bill.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20230607-guts-blurry-67e711acf328@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Saving off the `isa` pointer to a temp variable, followed by checking if
it has been incremented is a bit of an odd pattern. Perhaps it was done
to avoid a funky looking if statement mixed with the ifdeffery.
Now that we use IS_ENABLED() here just return from the parser as soon as
we detect a mismatch between the string and the currently running
kernel.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>
Link: https://lore.kernel.org/r/20230607-splatter-bacterium-a75bb9f0d0b7@spud
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Evan Green <evan@rivosinc.com> says:
This change detects the presence of Zba, Zbb, and Zbs extensions and exports
them per-hart to userspace via the hwprobe mechanism. Glibc can then use
these in setting up hwcaps-based library search paths.
There's a little bit of extra housekeeping here: the first change adds
Zba and Zbs to the set of extensions the kernel recognizes, and the second
change starts tracking ISA features per-hart (in addition to the ANDed
mask of features across all harts which the kernel uses to make
decisions). Now that we track the ISA information per-hart, we could
even fix up /proc/cpuinfo to accurately report extension per-hart,
though I've left that out of this series for now.
* b4-shazam-merge:
RISC-V: hwprobe: Expose Zba, Zbb, and Zbs
RISC-V: Track ISA extensions per hart
RISC-V: Add Zba, Zbs extension probing
Link: https://lore.kernel.org/r/20230509182504.2997252-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The kernel maintains a mask of ISA extensions ANDed together across all
harts. Let's also keep a bitmap of ISA extensions for each CPU. Although
the kernel is currently unlikely to enable a feature that exists only on
some CPUs, we want the ability to report asymmetric CPU extensions
accurately to usermode.
Note that riscv_fill_hwcaps() runs before the per_cpu_offsets are built,
which is why I've used a [NR_CPUS] array rather than per_cpu() data.
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20230509182504.2997252-3-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add the Zba address bit manipulation extension and Zbs single bit
instructions extension into those the kernel is aware of and maintains
in its riscv_isa bitmap.
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230509182504.2997252-2-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
If Zicbom is present but there was no riscv,cbom-blocks-size property found
during the cpu feeatures probe, or the cbom-block-size is not valid, then
the extension will be disabled. Make the print explicitly say this is
disabled to ensure that there is no confusion about what is being done.
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230317134512.254627-1-ben.dooks@codethink.co.uk
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andy Chiu <andy.chiu@sifive.com> says:
This is the v21 patch series for adding Vector extension support in
Linux. Please refer to [1] for the introduction of the patchset. The
v21 patch series was aimed to solve build issues from v19, provide usage
guideline for the prctl interface, and address review comments on v20.
Thank every one who has been reviewing, suggesting on the topic. Hope
this get a step closer to the final merge.
* b4-shazam-merge: (27 commits)
selftests: add .gitignore file for RISC-V hwprobe
selftests: Test RISC-V Vector prctl interface
riscv: Add documentation for Vector
riscv: Enable Vector code to be built
riscv: detect assembler support for .option arch
riscv: Add sysctl to set the default vector rule for new processes
riscv: Add prctl controls for userspace vector management
riscv: hwcap: change ELF_HWCAP to a function
riscv: KVM: Add vector lazy save/restore support
riscv: kvm: Add V extension to KVM ISA
riscv: prevent stack corruption by reserving task_pt_regs(p) early
riscv: signal: validate altstack to reflect Vector
riscv: signal: Report signal frame size to userspace via auxv
riscv: signal: Add sigcontext save/restore for vector
riscv: signal: check fp-reserved words unconditionally
riscv: Add ptrace vector support
riscv: Allocate user's vector context in the first-use trap
riscv: Add task switch support for vector
riscv: Introduce struct/helpers to save/restore per-task Vector state
riscv: Introduce riscv_v_vsize to record size of Vector context
...
Link: https://lore.kernel.org/r/20230605110724.21391-1-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This patch add two riscv-specific prctls, to allow usespace control the
use of vector unit:
* PR_RISCV_V_SET_CONTROL: control the permission to use Vector at next,
or all following execve for a thread. Turning off a thread's Vector
live is not possible since libraries may have registered ifunc that
may execute Vector instructions.
* PR_RISCV_V_GET_CONTROL: get the same permission setting for the
current thread, and the setting for following execve(s).
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
Link: https://lore.kernel.org/r/20230605110724.21391-22-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Using a function is flexible to represent ELF_HWCAP. So the kernel may
encode hwcap reflecting supported hardware features just at the moment of
the start of each program.
This will be helpful when we introduce prctl/sysctl interface to control
per-process availability of Vector extension in following patches.
Programs started with V disabled should see V masked off in theirs
ELF_HWCAP.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230605110724.21391-21-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This patch is used to detect the size of CPU vector registers and use
riscv_v_vsize to save the size of all the vector registers. It assumes all
harts has the same capabilities in a SMP system. If a core detects VLENB
that is different from the boot core, then it warns and turns off V
support for user space.
Co-developed-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Co-developed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20230605110724.21391-9-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Yangyu Chen <cyy@cyyself.name> says:
This patchset allows case-insensitive ISA string parsing, which is
needed in the ACPI environment. As the RISC-V Hart Capabilities Table
(RHCT) description in UEFI Forum ECR[1] shows the format of the ISA
string is defined in the RISC-V unprivileged specification[2]. However,
the RISC-V unprivileged specification defines the ISA naming strings are
case-insensitive while the current ISA string parser in the kernel only
accepts lowercase letters. In this case, the kernel should allow
case-insensitive ISA string parsing. Moreover, this reason has been
discussed in Conor's patch[3]. And I have also checked the current ISA
string parsing in the recent ACPI support patch[4] will also call
`riscv_fill_hwcap` function as DT we use now.
The original motivation for my patch v1[5] is that some SoC generators
will provide generated DT with illegal ISA string in dt-binding such as
rocket-chip, which will even cause kernel panic in some cases as I
mentioned in v1[5]. Now, the rocket-chip has been fixed in PR #3333[6].
However, when using some specific version of rocket-chip with
illegal ISA string in DT, this patchset will also work for parsing
uppercase letters correctly in DT, thus will have better compatibility.
In summary, this patch not only works for case-insensitive ISA string
parsing to meet the requirements in ECR[1] but also can be a workaround
for some specific versions of rocket-chip.
* b4-shazam-merge:
dt-bindings: riscv: drop invalid comment about riscv,isa lower-case reasoning
riscv: allow case-insensitive ISA string parsing
Link: https://lore.kernel.org/r/tencent_E6911C8D71F5624E432A1AFDF86804C3B509@qq.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
According to RISC-V Hart Capabilities Table (RHCT) description in UEFI
Forum ECR, the format of the ISA string is defined in the RISC-V
unprivileged specification which is case-insensitive. However, the
current ISA string parser in the kernel does not support ISA strings
with uppercase letters.
This patch modifies the ISA string parser in the kernel to support
case-insensitive ISA string parsing.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Yangyu Chen <cyy@cyyself.name>
Link: https://lore.kernel.org/r/tencent_B30EED51C7235CA1988890E5C658BE35C107@qq.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
On ACPI based systems, the information about the hart
like ISA is provided by the RISC-V Hart Capabilities Table (RHCT).
Enable filling up hwcap structure based on the information in RHCT.
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-15-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
During boot we call riscv_of_processor_hartid() for each hart that we
add to the possible cpus list. Repeating the call again here is not
required, if we iterate over the list of possible CPUs, rather than the
list of all CPUs.
The call to of_property_read_string() for "riscv,isa" cannot fail
either, as it has previously succeeded in riscv_of_processor_hartid(),
but leaving in the error checking makes the operation of the loop more
obvious & provides leeway for future refactoring of
riscv_of_processor_hartid().
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Co-developed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-14-sunilvl@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
* Support for hibernation.
* .rela.dyn has been moved to init.
* A fix for the SBI probing to allow for implementation-defined
behavior.
* Various other fixes and cleanups throughout the tree.
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Merge tag 'riscv-for-linus-6.4-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull more RISC-V updates from Palmer Dabbelt:
- Support for hibernation
- The .rela.dyn section has been moved to the init area
- A fix for the SBI probing to allow for implementation-defined
behavior
- Various other fixes and cleanups throughout the tree
* tag 'riscv-for-linus-6.4-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
RISC-V: include cpufeature.h in cpufeature.c
riscv: Move .rela.dyn to the init sections
dt-bindings: riscv: explicitly mention assumption of Zicsr & Zifencei support
riscv: compat_syscall_table: Fixup compile warning
RISC-V: fixup in-flight collision with ARCH_WANT_OPTIMIZE_VMEMMAP rename
RISC-V: fix sifive and thead section mismatches in errata
RISC-V: Align SBI probe implementation with spec
riscv: mm: remove redundant parameter of create_fdt_early_page_table
riscv: Adjust dependencies of HAVE_DYNAMIC_FTRACE selection
RISC-V: Add arch functions to support hibernation/suspend-to-disk
RISC-V: mm: Enable huge page support to kernel_page_present() function
RISC-V: Factor out common code of __cpu_resume_enter()
RISC-V: Change suspend_save_csrs and suspend_restore_csrs to public function
Automation complains:
warning: symbol '__pcpu_scope_misaligned_access_speed' was not declared. Should it be static?
cpufeature.c doesn't actually include the header of the same name, as it
had not previously used anything from it.
The per-cpu variable is declared there, so include it to silence the
complaints.
Fixes: 62a31d6e38bd ("RISC-V: hwprobe: Support probing of misaligned access performance")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Evan Green <evan@rivosinc.com>
Link: https://lore.kernel.org/r/20230420-wound-gizzard-2b2b589d9bea@spud
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
We have two extension names for AIA ISA support: Smaia (M-mode AIA CSRs)
and Ssaia (S-mode AIA CSRs).
We extend the ISA string parsing to detect Smaia and Ssaia extensions.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Anup Patel <anup@brainfault.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Evan Green <evan@rivosinc.com> says:
There's been a bunch of off-list discussions about this, including at
Plumbers. The original plan was to do something involving providing an
ISA string to userspace, but ISA strings just aren't sufficient for a
stable ABI any more: in order to parse an ISA string users need the
version of the specifications that the string is written to, the version
of each extension (sometimes at a finer granularity than the RISC-V
releases/versions encode), and the expected use case for the ISA string
(ie, is it a U-mode or M-mode string). That's a lot of complexity to
try and keep ABI compatible and it's probably going to continue to grow,
as even if there's no more complexity in the specifications we'll have
to deal with the various ISA string parsing oddities that end up all
over userspace.
Instead this patch set takes a very different approach and provides a set
of key/value pairs that encode various bits about the system. The big
advantage here is that we can clearly define what these mean so we can
ensure ABI stability, but it also allows us to encode information that's
unlikely to ever appear in an ISA string (see the misaligned access
performance, for example). The resulting interface looks a lot like
what arm64 and x86 do, and will hopefully fit well into something like
ACPI in the future.
The actual user interface is a syscall, with a vDSO function in front of
it. The vDSO function can answer some queries without a syscall at all,
and falls back to the syscall for cases it doesn't have answers to.
Currently we prepopulate it with an array of answers for all keys and
a CPU set of "all CPUs". This can be adjusted as necessary to provide
fast answers to the most common queries.
An example series in glibc exposing this syscall and using it in an
ifunc selector for memcpy can be found at [1].
I was asked about the performance delta between this and something like
sysfs. I created a small test program and ran it on a Nezha D1
Allwinner board. Doing each operation 100000 times and dividing, these
operations take the following amount of time:
- open()+read()+close() of /sys/kernel/cpu_byteorder: 3.8us
- access("/sys/kernel/cpu_byteorder", R_OK): 1.3us
- riscv_hwprobe() vDSO and syscall: .0094us
- riscv_hwprobe() vDSO with no syscall: 0.0091us
These numbers get farther apart if we query multiple keys, as sysfs will
scale linearly with the number of keys, where the dedicated syscall
stays the same. To frame these numbers, I also did a tight
fork/exec/wait loop, which I measured as 4.8ms. So doing 4
open/read/close operations is a delta of about 0.3%, versus a single vDSO
call is a delta of essentially zero.
[1] https://patchwork.ozlabs.org/project/glibc/list/?series=343050
* b4-shazam-merge:
RISC-V: Add hwprobe vDSO function and data
selftests: Test the new RISC-V hwprobe interface
RISC-V: hwprobe: Support probing of misaligned access performance
RISC-V: hwprobe: Add support for RISCV_HWPROBE_BASE_BEHAVIOR_IMA
RISC-V: Add a syscall for HW probing
RISC-V: Move struct riscv_cpuinfo to new header
Link: https://lore.kernel.org/r/20230407231103.2622178-1-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This allows userspace to select various routines to use based on the
performance of misaligned access on the target hardware.
Rather than adding DT bindings, this change taps into the alternatives
mechanism used to probe CPU errata. Add a new function pointer alongside
the vendor-specific errata_patch_func() that probes for desirable errata
(otherwise known as "features"). Unlike the errata_patch_func(), this
function is called on each CPU as it comes up, so it can save
feature information per-CPU.
The T-head C906 has fast unaligned access, both as defined by GCC [1],
and in performing a basic benchmark, which determined that byte copies
are >50% slower than a misaligned word copy of the same data size (source
for this test at [2]):
bytecopy size f000 count 50000 offset 0 took 31664899 us
wordcopy size f000 count 50000 offset 0 took 5180919 us
wordcopy size f000 count 50000 offset 1 took 13416949 us
[1] https://github.com/gcc-mirror/gcc/blob/master/gcc/config/riscv/riscv.cc#L353
[2] https://pastebin.com/EPXvDHSW
Co-developed-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>
Link: https://lore.kernel.org/r/20230407231103.2622178-5-evan@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andrew Jones <ajones@ventanamicro.com> says:
When the Zicboz extension is available we can more rapidly zero naturally
aligned Zicboz block sized chunks of memory. As pages are always page
aligned and are larger than any Zicboz block size will be, then
clear_page() appears to be a good candidate for the extension. While cycle
count and energy consumption should also be considered, we can be pretty
certain that implementing clear_page() with the Zicboz extension is a win
by comparing the new dynamic instruction count with its current count[1].
Doing so we see that the new count is just over a quarter of the old count
(see patch6's commit message for more details).
For those of you who reviewed v1[2], you may be looking for the memset()
patches. As pointed out in v1, and a couple follow-up emails, it's not
clear that patching memset() is a win yet. When I get a chance to test
on real hardware with a comprehensive benchmark collection then I can
post the memset() patches separately (assuming the benchmarks show it's
worthwhile).
* b4-shazam-merge:
RISC-V: KVM: Expose Zicboz to the guest
RISC-V: KVM: Provide UAPI for Zicboz block size
RISC-V: Use Zicboz in clear_page when available
RISC-V: cpufeatures: Put the upper 16 bits of patch ID to work
RISC-V: Add Zicboz detection and block size parsing
dt-bindings: riscv: Document cboz-block-size
RISC-V: Factor out body of riscv_init_cbom_blocksize loop
RISC-V: alternatives: Support patching multiple insns in assembly
Link: https://lore.kernel.org/r/20230224162631.405473-1-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Using memset() to zero a 4K page takes 563 total instructions, where
20 are branches. clear_page(), with Zicboz and a 64 byte block size,
takes 169 total instructions, where 4 are branches and 33 are nops.
Even though the block size is a variable, thanks to alternatives, we
can still implement a Duff device without having to do any preliminary
calculations. This is achieved by using the alternatives' cpufeature
value (the upper 16 bits of patch_id). The value used is the maximum
zicboz block size order accepted at the patch site. This enables us
to stop patching / unrolling when 4K bytes have been zeroed (we would
loop and continue after 4K if the page size would be larger)
For 4K pages, unrolling 16 times allows block sizes of 64 and 128 to
only loop a few times and larger block sizes to not loop at all. Since
cbo.zero doesn't take an offset, we also need an 'add' after each
instruction, making the loop body 112 to 160 bytes. Hopefully this
is small enough to not cause icache misses.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-7-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
cpufeature IDs are consecutive integers starting at 26, so a 32-bit
patch ID allows an aircraft carrier load of feature IDs. Repurposing
the upper 16 bits still leaves a boat load of feature IDs and gains
16 bits which may be used to control patching on a per patch-site
basis.
This will be initially used in Zicboz's application to clear_page(),
as Zicboz's block size must also be considered. In that case, the
upper 16-bit value's role will be to convey the maximum block size
which the Zicboz clear_page() implementation supports.
cpufeature patch sites which need to check for the existence or
absence of other cpufeatures may also be able to make use of this.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-6-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Parse "riscv,cboz-block-size" from the DT by piggybacking on Zicbom's
riscv_init_cbom_blocksize(). Additionally check the DT for the presence
of the "zicboz" extension and, when it's present, validate the parsed
cboz block size as we do Zicbom's cbom block size with
riscv_isa_extension_check().
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230224162631.405473-5-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Andrew Jones <ajones@ventanamicro.com> says:
This series has no intended functional change. These cleanups were
found while renaming errata_id to patch_id in order to better
convey that its purpose is larger than errata (it's also for
cpufeatures).
* b4-shazam-merge:
riscv: cpufeature: Drop errata_list.h and other unused includes
riscv: lib: Include hwcap.h directly
riscv: alternatives: Rename errata_id to patch_id
riscv: alternatives: Remove unnecessary define and unused struct
riscv: Rename Kconfig.erratas to Kconfig.errata
riscv: Clarify RISCV_ALTERNATIVE help text
Link: https://lore.kernel.org/r/20230224154601.88163-1-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Drop errata_list.h, since cpufeature.c includes hwcap.h directly to
get cpufeature IDs. And, while there, prune the rest of the unused
includes too.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230224154601.88163-7-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Alternatives are used for both errata and cpufeatures. Use a more
generic name, 'patch_id', as in "ID of code patching site", to
avoid confusion when alternatives are used for cpufeatures.
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230224154601.88163-5-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Qinglin Pan <panqinglin00@gmail.com> says:
Svnapot is a RISC-V extension for marking contiguous 4K pages as a non-4K
page. This patch set is for using Svnapot in hugetlb fs and huge vmap.
This patchset adds a Kconfig item for using Svnapot in
"Platform type"->"SVNAPOT extension support". Its default value is on,
and people can set it off if they don't allow kernel to detect Svnapot
hardware support and leverage it.
Tested on:
- qemu rv64 with "Svnapot support" off and svnapot=true.
- qemu rv64 with "Svnapot support" on and svnapot=true.
- qemu rv64 with "Svnapot support" off and svnapot=false.
- qemu rv64 with "Svnapot support" on and svnapot=false.
* b4-shazam-merge:
riscv: mm: support Svnapot in huge vmap
riscv: mm: support Svnapot in hugetlb page
riscv: mm: modify pte format for Svnapot
Link: https://lore.kernel.org/r/20230209131647.17245-1-panqinglin00@gmail.com
[Palmer: fix up the feature ordering in the merge]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Add one alternative to enable/disable svnapot support, enable this static
key when "svnapot" is in the "riscv,isa" field of fdt and SVNAPOT compile
option is set. It will influence the behavior of has_svnapot. All code
dependent on svnapot should make sure that has_svnapot return true firstly.
Modify PTE definition for Svnapot, and creates some functions in pgtable.h
to mark a PTE as napot and check if it is a Svnapot PTE. Until now, only
64KB napot size is supported in spec, so some macros has only 64KB version.
Signed-off-by: Qinglin Pan <panqinglin00@gmail.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230209131647.17245-2-panqinglin00@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
