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517ffce4e1
linux/arch/sparc/kernel
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David S. Miller 517ffce4e1 sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 
The Montgomery Multiply, Montgomery Square, and Multiple-Precision
Multiply instructions work by loading a combination of the floating
point and multiple register windows worth of integer registers
with the inputs.

These values are 64-bit.  But for 32-bit userland processes we only
save the low 32-bits of each integer register during a register spill.
This is because the register window save area is in the user stack and
has a fixed layout.

Therefore, the only way to use these instruction in 32-bit mode is to
perform the following sequence:

1) Load the top-32bits of a choosen integer register with a sentinel,
   say "-1".  This will be in the outer-most register window.

   The idea is that we're trying to see if the outer-most register
   window gets spilled, and thus the 64-bit values were truncated.

2) Load all the inputs for the montmul/montsqr/mpmul instruction,
   down to the inner-most register window.

3) Execute the opcode.

4) Traverse back up to the outer-most register window.

5) Check the sentinel, if it's still "-1" store the results.
   Otherwise retry the entire sequence.

This retry is extremely troublesome.  If you're just unlucky and an
interrupt or other trap happens, it'll push that outer-most window to
the stack and clear the sentinel when we restore it.

We could retry forever and never make forward progress if interrupts
arrive at a fast enough rate (consider perf events as one example).
So we have do limited retries and fallback to software which is
extremely non-deterministic.

Luckily it's very straightforward to provide a mechanism to let
32-bit applications use a 64-bit stack.  Stacks in 64-bit mode are
biased by 2047 bytes, which means that the lowest bit is set in the
actual %sp register value.

So if we see bit zero set in a 32-bit application's stack we treat
it like a 64-bit stack.

Runtime detection of such a facility is tricky, and cumbersome at
best.  For example, just trying to use a biased stack and seeing if it
works is hard to recover from (the signal handler will need to use an
alt stack, plus something along the lines of longjmp).  Therefore, we
add a system call to report a bitmask of arch specific features like
this in a cheap and less hairy way.

With help from Andy Polyakov.

Signed-off-by: David S. Miller <davem@davemloft.net>
2012-10-26 15:18:37 -07:00
..
.gitignore
apc.c sparc: Add module.h to files previously implicitly using it. 2011-10-31 19:30:54 -04:00
asm-offsets.c
audit.c
auxio_32.c sparc32: Remove sun4 and sun4c from enum sparc_cpu. 2012-05-12 00:23:23 -07:00
auxio_64.c sparc64: Fix section mis-match errors. 2011-03-30 17:37:56 -07:00
btext.c sparc: remove several unnecessary module.h include instances 2011-10-31 19:30:54 -04:00
central.c sparc64: Do not clobber %g2 in xcall_fetch_glob_regs(). 2012-05-10 11:00:46 -07:00
cherrs.S
chmc.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
compat_audit.c
cpu.c sparc32: handle leon in cpu.c 2012-05-27 23:52:45 -07:00
cpumap.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
cpumap.h
devices.c sparc32: remove sun4c traps 2012-05-11 19:27:46 -07:00
dma.c sparc: remove several unnecessary module.h include instances 2011-10-31 19:30:54 -04:00
ds.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc 2012-04-13 13:32:07 -07:00
dtlb_miss.S
dtlb_prot.S
ebus.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
entry.h sparc64: Patch sun4v code sequences properly on module load. 2011-11-17 22:44:58 -08:00
entry.S sparc32: introduce support for run-time patching for all shared assembler code 2012-05-27 23:52:49 -07:00
etrap_32.S sparc32: introduce support for run-time patching for all shared assembler code 2012-05-27 23:52:49 -07:00
etrap_64.S Revert strace hiccups fix. 2012-10-05 20:39:04 -07:00
fpu_traps.S
ftrace.c
getsetcc.S
head_32.S sparc32: drop swapper_pg_dir 2012-07-26 16:46:15 -07:00
head_64.S sparc64: Niagara-4 bzero/memset, plus use MRU stores in page copy. 2012-10-05 13:45:26 -07:00
helpers.S
hvapi.c sparc: fix format string argument for prom_printf() 2012-10-02 23:20:34 -04:00
hvcalls.S sparc64: Add hypervisor interfaces for SPARC-T4 perf counter access. 2012-08-18 23:03:53 -07:00
hvtramp.S
idprom.c sparc: Clear out unused asm/machines.h values. 2012-05-11 20:45:18 -07:00
iommu_common.h
iommu.c SPARC: adapt for dma_map_ops changes 2012-03-28 16:36:34 +02:00
ioport.c sparc32: Export leon_dma_ops to modules. 2012-05-28 00:07:03 -07:00
irq_32.c sparc32: handle leon in irq_32.c 2012-05-27 23:52:44 -07:00
irq_64.c sparc32: Trivial removal of sun4c references in comments. 2012-05-12 00:35:45 -07:00
irq.h sparc32: remove runtime btfix support 2012-05-14 14:05:09 -07:00
itlb_miss.S
ivec.S
jump_label.c sparc: Fix even more fallout from system.h split. 2012-03-29 22:40:52 -07:00
kernel.h sparc32: introduce sparc32_start_kernel called from head_32.S 2012-05-27 23:52:42 -07:00
kgdb_32.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
kgdb_64.c sparc: Fix even more fallout from system.h split. 2012-03-29 22:40:52 -07:00
kprobes.c
kstack.h
ktlb.S sparc64: Support 2GB and 16GB page sizes for kernel linear mappings. 2012-09-06 18:13:58 -07:00
ldc.c sparc/ldc: remove IRQF_SAMPLE_RANDOM which is now a no-op 2012-07-19 10:40:30 -04:00
led.c
leon_kernel.c sparc32,leon: drop leon_init() 2012-07-26 16:46:16 -07:00
leon_pci_grpci2.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
leon_pci.c PCI: Provide a default pcibios_update_irq() 2012-09-18 17:28:21 -06:00
leon_pmc.c sparc32,leon: always include leon_pmc in build 2012-05-27 23:52:53 -07:00
leon_smp.c sparc32,leon: fix section mismatch warning 2012-05-27 23:52:48 -07:00
Makefile sparc32,leon: always include leon_pmc in build 2012-05-27 23:52:53 -07:00
mdesc.c sparc64: Probe cpu page size support more portably. 2012-09-06 19:01:25 -07:00
misctrap.S
module.c sparc: fix the return value of module_alloc() 2012-09-21 12:14:20 -07:00
nmi.c sparc64: Abstract away the %pcr values used to enable/disable NMI 2012-08-18 23:26:19 -07:00
of_device_32.c sparc32: rename sparc_irq_config to sparc_config 2012-04-15 10:28:49 -07:00
of_device_64.c devicetree: add helper inline for retrieving a node's full name 2012-07-06 07:16:34 -05:00
of_device_common.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
of_device_common.h
pci_common.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
pci_fire.c sparc: add export.h to arch/sparc files as required 2011-10-31 19:30:52 -04:00
pci_impl.h sparc/PCI: register busn_res for root buses 2012-06-13 15:42:24 -06:00
pci_msi.c sparc: convert old cpumask API into new one 2011-05-16 13:38:07 -07:00
pci_psycho.c sparc: add export.h to arch/sparc files as required 2011-10-31 19:30:52 -04:00
pci_sabre.c sparc: add export.h to arch/sparc files as required 2011-10-31 19:30:52 -04:00
pci_schizo.c sparc: add export.h to arch/sparc files as required 2011-10-31 19:30:52 -04:00
pci_sun4v_asm.S
pci_sun4v.c arch/sparc/kernel/pci_sun4v.c: removes unnecessary semicolon 2012-09-21 12:08:56 -07:00
pci_sun4v.h
pci.c mm: kill vma flag VM_RESERVED and mm->reserved_vm counter 2012-10-09 16:22:19 +09:00
pcic.c Merge branch 'pci/myron-pcibios_setup' into next 2012-07-05 15:31:05 -06:00
pcr.c sparc64: Add PCR ops for SPARC-T4. 2012-08-18 23:26:19 -07:00
perf_event.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
pmc.c sparc: Add module.h to files previously implicitly using it. 2011-10-31 19:30:54 -04:00
power.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
process_32.c vfs: define struct filename and have getname() return it 2012-10-12 20:14:55 -04:00
process_64.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
prom_32.c sparc: remove several unnecessary module.h include instances 2011-10-31 19:30:54 -04:00
prom_64.c sparc: fix format string argument for prom_printf() 2012-10-02 23:20:34 -04:00
prom_common.c sparc: fix sparc64 build due to leon.h inclusion 2012-05-29 12:47:38 -07:00
prom_irqtrans.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
prom.h
psycho_common.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
psycho_common.h
ptrace_32.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
ptrace_64.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
reboot.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
rtrap_32.S sparc32: introduce support for run-time patching for all shared assembler code 2012-05-27 23:52:49 -07:00
rtrap_64.S sparc64: Remove trap return code which is now unnecessary. 2012-04-13 13:56:46 -07:00
sbus.c sparc: add export.h to arch/sparc files as required 2011-10-31 19:30:52 -04:00
setup_32.c sparc32: centralize all mmu context handling in srmmu.c 2012-07-26 16:46:16 -07:00
setup_64.c sparc64: Add detection for features new in SPARC-T4. 2012-08-18 23:02:36 -07:00
signal32.c compat: move compat_siginfo_t definition to asm/compat.h 2012-10-06 03:05:16 +09:00
signal_32.c new helper: signal_delivered() 2012-06-01 12:58:52 -04:00
signal_64.c new helper: signal_delivered() 2012-06-01 12:58:52 -04:00
sigutil_32.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
sigutil_64.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
sigutil.h sparc: Allow handling signals when stack is corrupted. 2011-08-20 17:14:54 -07:00
smp_32.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-21 19:43:57 -07:00
smp_64.c sparc64: Add global PMU register dumping via sysrq. 2012-10-16 09:34:01 -07:00
sparc_ksyms_32.c sparc32: Implement hard_smp_processor_id() via instruction patching. 2012-05-14 13:31:38 -07:00
sparc_ksyms_64.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
spiterrs.S
sstate.c sparc: Set reboot-cmd using reboot data hypervisor call if available. 2011-08-02 21:28:52 -07:00
stacktrace.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
starfire.c sparc: explicitly cast negative phandle checks to s32 2011-01-03 20:02:06 -07:00
sun4d_irq.c sparc32: remove remaining users of btfixup 2012-05-14 14:05:08 -07:00
sun4d_smp.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-21 19:43:57 -07:00
sun4m_irq.c sparc32: remove remaining users of btfixup 2012-05-14 14:05:08 -07:00
sun4m_smp.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-21 19:43:57 -07:00
sun4v_ivec.S
sun4v_tlb_miss.S sparc64: Support transparent huge pages. 2012-10-09 16:23:06 +09:00
sys32.S compat: fs: Generic compat_sys_sendfile implementation 2012-10-02 21:35:55 -04:00
sys_sparc32.c vfs: define struct filename and have getname() return it 2012-10-12 20:14:55 -04:00
sys_sparc_32.c sparc: kill ancient comment in sparc_sigaction() 2012-05-21 23:59:23 -04:00
sys_sparc_64.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
syscalls.S sparc64: fix ptrace interaction with force_successful_syscall_return() 2012-10-10 17:25:00 -07:00
sysfs.c cpu: convert 'cpu' and 'machinecheck' sysdev_class to a regular subsystem 2011-12-21 14:29:42 -08:00
systbls_32.S sparc: Hook up process_vm_{readv,writev} syscalls. 2011-11-01 00:51:30 -07:00
systbls_64.S sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
systbls.h
tadpole.c
time_32.c sparc32: remove runtime btfix support 2012-05-14 14:05:09 -07:00
time_64.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
trampoline_32.S sparc32,leon: always include leon_smp + leon_mm in build 2012-05-27 23:52:47 -07:00
trampoline_64.S
traps_32.c sparc32: Kill off software 32-bit multiply/divide routines. 2012-05-15 11:23:47 -07:00
traps_64.c sparc64: Fix deficiencies in sun4v error reporting. 2012-10-10 17:19:32 -07:00
tsb.S sparc64: Support transparent huge pages. 2012-10-09 16:23:06 +09:00
ttable_32.S sparc32: move trap table to a separate file 2012-05-19 23:27:25 -07:00
ttable_64.S sparc64: renamed ttable.S to ttable_64.S 2012-05-19 23:26:41 -07:00
una_asm_32.S sparc32: unaligned memory access (MNA) trap handler bug 2011-02-01 12:39:59 -08:00
una_asm_64.S sparc: Fix .size directive for do_int_load 2011-03-16 18:19:15 -07:00
unaligned_32.c Disintegrate asm/system.h for Sparc 2012-03-28 18:30:03 +01:00
unaligned_64.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
us2e_cpufreq.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
us3_cpufreq.c sparc: Remove unnecessary semicolons 2011-06-07 16:06:34 -07:00
utrap.S
vio.c Fix typo in printed messages 2012-06-24 11:03:52 -07:00
viohs.c sparc: move symbol exporters to use export.h not module.h 2011-10-31 19:30:53 -04:00
visemul.c sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
vmlinux.lds.S sparc32: add support for run-time patching of leon/sun single instructions 2012-05-27 23:52:43 -07:00
windows.c
winfixup.S sparc64: Make montmul/montsqr/mpmul usable in 32-bit threads. 2012-10-26 15:18:37 -07:00
wof.S sparc32: introduce support for run-time patching for all shared assembler code 2012-05-27 23:52:49 -07:00
wuf.S sparc32: introduce support for run-time patching for all shared assembler code 2012-05-27 23:52:49 -07:00