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For BPF_PSEUDO_FUNC instruction, verifier will refill imm with
correct addresses of bpf_calls and then run last pass of JIT.
Since the emit_imm of RV64 is variable-length, which will emit
appropriate length instructions accorroding to the imm, it may
broke ctx->offset, and lead to unpredictable problem, such as
inaccurate jump. So let's fix it with fixed-length instructions.
Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Suggested-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20221206091410.1584784-1-pulehui@huaweicloud.com
This patch implement more BPF atomic operations for RV64. The newly
added operations are shown below:
atomic[64]_[fetch_]add
atomic[64]_[fetch_]and
atomic[64]_[fetch_]or
atomic[64]_xchg
atomic[64]_cmpxchg
Since riscv specification does not provide AMO instruction for CAS
operation, we use lr/sc instruction for cmpxchg operation, and AMO
instructions for the rest ops.
Tests "test_bpf.ko" and "test_progs -t atomic" have passed, as well
as "test_verifier" with no new failure cases.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20220410101246.232875-1-pulehui@huawei.com
* Support for the DA9063 as used on the HiFive Unmatched.
* Support for relative extables, which puts us in line with other
architectures and save some space in vmlinux.
* A handful of kexec fixes/improvements, including the ability to run
crash kernels from PCI-addressable memory on the HiFive Unmatched.
* Support for the SBI SRST extension, which allows systems that do not
have an explicit driver in Linux to reboot.
* A handful of fixes and cleanups, including to the defconfigs and
device trees.
---
This time I do expect to have a part 2, as there's still some smaller
patches on the list. I was hoping to get through more of that over the
weekend, but I got distracted with the ABI issues. Figured it's better
to send this sooner rather than waiting.
Included are my merge resolutions against a master from this morning, if
that helps any:
diff --cc arch/riscv/include/asm/sbi.h
index 289621da4a2a,9c46dd3ff4a2..000000000000
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@@ -27,7 -27,14 +27,15 @@@ enum sbi_ext_id
SBI_EXT_IPI = 0x735049,
SBI_EXT_RFENCE = 0x52464E43,
SBI_EXT_HSM = 0x48534D,
+ SBI_EXT_SRST = 0x53525354,
+
+ /* Experimentals extensions must lie within this range */
+ SBI_EXT_EXPERIMENTAL_START = 0x08000000,
+ SBI_EXT_EXPERIMENTAL_END = 0x08FFFFFF,
+
+ /* Vendor extensions must lie within this range */
+ SBI_EXT_VENDOR_START = 0x09000000,
+ SBI_EXT_VENDOR_END = 0x09FFFFFF,
};
enum sbi_ext_base_fid {
diff --git a/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
index e03a4c94cf3f..6bfa1f24d3de 100644
--- a/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
+++ b/arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts
@@ -188,14 +188,6 @@ vdd_ldo11: ldo11 {
regulator-always-on;
};
};
-
- rtc {
- compatible = "dlg,da9063-rtc";
- };
-
- wdt {
- compatible = "dlg,da9063-watchdog";
- };
};
};
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Merge tag 'riscv-for-linus-5.17-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
- Support for the DA9063 as used on the HiFive Unmatched.
- Support for relative extables, which puts us in line with other
architectures and save some space in vmlinux.
- A handful of kexec fixes/improvements, including the ability to run
crash kernels from PCI-addressable memory on the HiFive Unmatched.
- Support for the SBI SRST extension, which allows systems that do not
have an explicit driver in Linux to reboot.
- A handful of fixes and cleanups, including to the defconfigs and
device trees.
* tag 'riscv-for-linus-5.17-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (52 commits)
RISC-V: Use SBI SRST extension when available
riscv: mm: fix wrong phys_ram_base value for RV64
RISC-V: Use common riscv_cpuid_to_hartid_mask() for both SMP=y and SMP=n
riscv: head: remove useless __PAGE_ALIGNED_BSS and .balign
riscv: errata: alternative: mark vendor_patch_func __initdata
riscv: head: make secondary_start_common() static
riscv: remove cpu_stop()
riscv: try to allocate crashkern region from 32bit addressible memory
riscv: use hart id instead of cpu id on machine_kexec
riscv: Don't use va_pa_offset on kdump
riscv: dts: sifive: fu540-c000: Fix PLIC node
riscv: dts: sifive: fu540-c000: Drop bogus soc node compatible values
riscv: dts: sifive: Group tuples in register properties
riscv: dts: sifive: Group tuples in interrupt properties
riscv: dts: microchip: mpfs: Group tuples in interrupt properties
riscv: dts: microchip: mpfs: Fix clock controller node
riscv: dts: microchip: mpfs: Fix reference clock node
riscv: dts: microchip: mpfs: Fix PLIC node
riscv: dts: microchip: mpfs: Drop empty chosen node
riscv: dts: canaan: Group tuples in interrupt properties
...
This is a riscv port of commit d6e2cc564775 ("arm64: extable: add `type`
and `data` fields").
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The return values of fixup_exception() and riscv_bpf_fixup_exception()
represent a boolean condition rather than an error code, so it's better
to return `bool` rather than `int`.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This is to group riscv related extable related functions signature
into one file.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
In the current code, the actual max tail call count is 33 which is greater
than MAX_TAIL_CALL_CNT (defined as 32). The actual limit is not consistent
with the meaning of MAX_TAIL_CALL_CNT and thus confusing at first glance.
We can see the historical evolution from commit 04fd61ab36ec ("bpf: allow
bpf programs to tail-call other bpf programs") and commit f9dabe016b63
("bpf: Undo off-by-one in interpreter tail call count limit"). In order
to avoid changing existing behavior, the actual limit is 33 now, this is
reasonable.
After commit 874be05f525e ("bpf, tests: Add tail call test suite"), we can
see there exists failed testcase.
On all archs when CONFIG_BPF_JIT_ALWAYS_ON is not set:
# echo 0 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf
# dmesg | grep -w FAIL
Tail call error path, max count reached jited:0 ret 34 != 33 FAIL
On some archs:
# echo 1 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf
# dmesg | grep -w FAIL
Tail call error path, max count reached jited:1 ret 34 != 33 FAIL
Although the above failed testcase has been fixed in commit 18935a72eb25
("bpf/tests: Fix error in tail call limit tests"), it would still be good
to change the value of MAX_TAIL_CALL_CNT from 32 to 33 to make the code
more readable.
The 32-bit x86 JIT was using a limit of 32, just fix the wrong comments and
limit to 33 tail calls as the constant MAX_TAIL_CALL_CNT updated. For the
mips64 JIT, use "ori" instead of "addiu" as suggested by Johan Almbladh.
For the riscv JIT, use RV_REG_TCC directly to save one register move as
suggested by Björn Töpel. For the other implementations, no function changes,
it does not change the current limit 33, the new value of MAX_TAIL_CALL_CNT
can reflect the actual max tail call count, the related tail call testcases
in test_bpf module and selftests can work well for the interpreter and the
JIT.
Here are the test results on x86_64:
# uname -m
x86_64
# echo 0 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf test_suite=test_tail_calls
# dmesg | tail -1
test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [0/8 JIT'ed]
# rmmod test_bpf
# echo 1 > /proc/sys/net/core/bpf_jit_enable
# modprobe test_bpf test_suite=test_tail_calls
# dmesg | tail -1
test_bpf: test_tail_calls: Summary: 8 PASSED, 0 FAILED, [8/8 JIT'ed]
# rmmod test_bpf
# ./test_progs -t tailcalls
#142 tailcalls:OK
Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/1636075800-3264-1-git-send-email-yangtiezhu@loongson.cn
When a tracing BPF program attempts to read memory without using the
bpf_probe_read() helper, the verifier marks the load instruction with
the BPF_PROBE_MEM flag. Since the riscv JIT does not currently recognize
this flag it falls back to the interpreter.
Add support for BPF_PROBE_MEM, by appending an exception table to the
BPF program. If the load instruction causes a data abort, the fixup
infrastructure finds the exception table and fixes up the fault, by
clearing the destination register and jumping over the faulting
instruction.
A more generic solution would add a "handler" field to the table entry,
like on x86 and s390. The same issue in ARM64 is fixed in 800834285361
("bpf, arm64: Add BPF exception tables").
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Pu Lehui <pulehui@huawei.com>
Tested-by: Björn Töpel <bjorn@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/bpf/20211027111822.3801679-1-tongtiangen@huawei.com
In case of JITs, each of the JIT backends compiles the BPF nospec instruction
/either/ to a machine instruction which emits a speculation barrier /or/ to
/no/ machine instruction in case the underlying architecture is not affected
by Speculative Store Bypass or has different mitigations in place already.
This covers both x86 and (implicitly) arm64: In case of x86, we use 'lfence'
instruction for mitigation. In case of arm64, we rely on the firmware mitigation
as controlled via the ssbd kernel parameter. Whenever the mitigation is enabled,
it works for all of the kernel code with no need to provide any additional
instructions here (hence only comment in arm64 JIT). Other archs can follow
as needed. The BPF nospec instruction is specifically targeting Spectre v4
since i) we don't use a serialization barrier for the Spectre v1 case, and
ii) mitigation instructions for v1 and v4 might be different on some archs.
The BPF nospec is required for a future commit, where the BPF verifier does
annotate intermediate BPF programs with speculation barriers.
Co-developed-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Benedict Schlueter <benedict.schlueter@rub.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
We will drop the executable permissions of the code pages from the
mapping at allocation time soon. Move bpf_jit_alloc_exec() and
bpf_jit_free_exec() to bpf_jit_core.c so that they can be shared by
both RV64I and RV32I.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
A subsequent patch will add additional atomic operations. These new
operations will use the same opcode field as the existing XADD, with
the immediate discriminating different operations.
In preparation, rename the instruction mode BPF_ATOMIC and start
calling the zero immediate BPF_ADD.
This is possible (doesn't break existing valid BPF progs) because the
immediate field is currently reserved MBZ and BPF_ADD is zero.
All uses are removed from the tree but the BPF_XADD definition is
kept around to avoid breaking builds for people including kernel
headers.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-5-jackmanb@google.com
This patch uses the RVC support and encodings from bpf_jit.h to optimize
the rv64 jit.
The optimizations work by replacing emit(rv_X(...)) with a call to a
helper function emit_X, which will emit a compressed version of the
instruction when possible, and when RVC is enabled.
The JIT continues to pass all tests in lib/test_bpf.c, and introduces
no new failures to test_verifier; both with and without RVC being enabled.
Most changes are straightforward replacements of emit(rv_X(...), ctx)
with emit_X(..., ctx), with the following exceptions bearing mention;
* Change emit_imm to sign-extend the value in "lower", since the
checks for RVC (and the instructions themselves) treat the value as
signed. Otherwise, small negative immediates will not be recognized as
encodable using an RVC instruction. For example, without this change,
emit_imm(rd, -1, ctx) would cause lower to become 4095, which is not a
6b int even though a "c.li rd, -1" instruction suffices.
* For {BPF_MOV,BPF_ADD} BPF_X, drop using addiw,addw in the 32-bit
cases since the values are zero-extended into the upper 32 bits in
the following instructions anyways, and the addition commutes with
zero-extension. (BPF_SUB BPF_X must still use subw since subtraction
does not commute with zero-extension.)
This patch avoids optimizing branches and jumps to use RVC instructions
since surrounding code often makes assumptions about the sizes of
emitted instructions. Optimizing these will require changing these
functions (e.g., emit_branch) to dynamically compute jump offsets.
The following are examples of the JITed code for the verifier selftest
"direct packet read test#3 for CGROUP_SKB OK", without and with RVC
enabled, respectively. The former uses 178 bytes, and the latter uses 112,
for a ~37% reduction in code size for this example.
Without RVC:
0: 02000813 addi a6,zero,32
4: fd010113 addi sp,sp,-48
8: 02813423 sd s0,40(sp)
c: 02913023 sd s1,32(sp)
10: 01213c23 sd s2,24(sp)
14: 01313823 sd s3,16(sp)
18: 01413423 sd s4,8(sp)
1c: 03010413 addi s0,sp,48
20: 03056683 lwu a3,48(a0)
24: 02069693 slli a3,a3,0x20
28: 0206d693 srli a3,a3,0x20
2c: 03456703 lwu a4,52(a0)
30: 02071713 slli a4,a4,0x20
34: 02075713 srli a4,a4,0x20
38: 03856483 lwu s1,56(a0)
3c: 02049493 slli s1,s1,0x20
40: 0204d493 srli s1,s1,0x20
44: 03c56903 lwu s2,60(a0)
48: 02091913 slli s2,s2,0x20
4c: 02095913 srli s2,s2,0x20
50: 04056983 lwu s3,64(a0)
54: 02099993 slli s3,s3,0x20
58: 0209d993 srli s3,s3,0x20
5c: 09056a03 lwu s4,144(a0)
60: 020a1a13 slli s4,s4,0x20
64: 020a5a13 srli s4,s4,0x20
68: 00900313 addi t1,zero,9
6c: 006a7463 bgeu s4,t1,0x74
70: 00000a13 addi s4,zero,0
74: 02d52823 sw a3,48(a0)
78: 02e52a23 sw a4,52(a0)
7c: 02952c23 sw s1,56(a0)
80: 03252e23 sw s2,60(a0)
84: 05352023 sw s3,64(a0)
88: 00000793 addi a5,zero,0
8c: 02813403 ld s0,40(sp)
90: 02013483 ld s1,32(sp)
94: 01813903 ld s2,24(sp)
98: 01013983 ld s3,16(sp)
9c: 00813a03 ld s4,8(sp)
a0: 03010113 addi sp,sp,48
a4: 00078513 addi a0,a5,0
a8: 00008067 jalr zero,0(ra)
With RVC:
0: 02000813 addi a6,zero,32
4: 7179 c.addi16sp sp,-48
6: f422 c.sdsp s0,40(sp)
8: f026 c.sdsp s1,32(sp)
a: ec4a c.sdsp s2,24(sp)
c: e84e c.sdsp s3,16(sp)
e: e452 c.sdsp s4,8(sp)
10: 1800 c.addi4spn s0,sp,48
12: 03056683 lwu a3,48(a0)
16: 1682 c.slli a3,0x20
18: 9281 c.srli a3,0x20
1a: 03456703 lwu a4,52(a0)
1e: 1702 c.slli a4,0x20
20: 9301 c.srli a4,0x20
22: 03856483 lwu s1,56(a0)
26: 1482 c.slli s1,0x20
28: 9081 c.srli s1,0x20
2a: 03c56903 lwu s2,60(a0)
2e: 1902 c.slli s2,0x20
30: 02095913 srli s2,s2,0x20
34: 04056983 lwu s3,64(a0)
38: 1982 c.slli s3,0x20
3a: 0209d993 srli s3,s3,0x20
3e: 09056a03 lwu s4,144(a0)
42: 1a02 c.slli s4,0x20
44: 020a5a13 srli s4,s4,0x20
48: 4325 c.li t1,9
4a: 006a7363 bgeu s4,t1,0x50
4e: 4a01 c.li s4,0
50: d914 c.sw a3,48(a0)
52: d958 c.sw a4,52(a0)
54: dd04 c.sw s1,56(a0)
56: 03252e23 sw s2,60(a0)
5a: 05352023 sw s3,64(a0)
5e: 4781 c.li a5,0
60: 7422 c.ldsp s0,40(sp)
62: 7482 c.ldsp s1,32(sp)
64: 6962 c.ldsp s2,24(sp)
66: 69c2 c.ldsp s3,16(sp)
68: 6a22 c.ldsp s4,8(sp)
6a: 6145 c.addi16sp sp,48
6c: 853e c.mv a0,a5
6e: 8082 c.jr ra
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200721025241.8077-4-luke.r.nels@gmail.com
This patch makes the necessary changes to struct rv_jit_context and to
bpf_int_jit_compile to support compressed riscv (RVC) instructions in
the BPF JIT.
It changes the JIT image to be u16 instead of u32, since RVC instructions
are 2 bytes as opposed to 4.
It also changes ctx->offset and ctx->ninsns to refer to 2-byte
instructions rather than 4-byte ones. The riscv PC is required to be
16-bit aligned with or without RVC, so this is sufficient to refer to
any valid riscv offset.
The code for computing jump offsets in bytes is updated accordingly,
and factored into a new "ninsns_rvoff" function to simplify the code.
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200721025241.8077-2-luke.r.nels@gmail.com
This patch optimizes BPF_JSET BPF_K by using a RISC-V andi instruction
when the BPF immediate fits in 12 bits, instead of first loading the
immediate to a temporary register.
Examples of generated code with and without this optimization:
BPF_JMP_IMM(BPF_JSET, R1, 2, 1) without optimization:
20: li t1,2
24: and t1,a0,t1
28: bnez t1,0x30
BPF_JMP_IMM(BPF_JSET, R1, 2, 1) with optimization:
20: andi t1,a0,2
24: bnez t1,0x2c
BPF_JMP32_IMM(BPF_JSET, R1, 2, 1) without optimization:
20: li t1,2
24: mv t2,a0
28: slli t2,t2,0x20
2c: srli t2,t2,0x20
30: slli t1,t1,0x20
34: srli t1,t1,0x20
38: and t1,t2,t1
3c: bnez t1,0x44
BPF_JMP32_IMM(BPF_JSET, R1, 2, 1) with optimization:
20: andi t1,a0,2
24: bnez t1,0x2c
In these examples, because the upper 32 bits of the sign-extended
immediate are 0, BPF_JMP BPF_JSET and BPF_JMP32 BPF_JSET are equivalent
and therefore the JIT produces identical code for them.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200506000320.28965-5-luke.r.nels@gmail.com
This patch adds an optimization to BPF_JMP (32- and 64-bit) BPF_K for
when the BPF immediate is zero.
When the immediate is zero, the code can directly use the RISC-V zero
register instead of loading a zero immediate to a temporary register
first.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200506000320.28965-4-luke.r.nels@gmail.com
This patch adds two optimizations for BPF_ALU BPF_END BPF_FROM_LE in
the RV64 BPF JIT.
First, it enables the verifier zero-extension optimization to avoid zero
extension when imm == 32. Second, it avoids generating code for imm ==
64, since it is equivalent to a no-op.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200506000320.28965-3-luke.r.nels@gmail.com
Commit 66d0d5a854a6 ("riscv: bpf: eliminate zero extension code-gen")
added support for the verifier zero-extension optimization on RV64 and
commit 46dd3d7d287b ("bpf, riscv: Enable zext optimization for more
RV64G ALU ops") enabled it for more instruction cases.
However, BPF_LSH BPF_X and BPF_{LSH,RSH,ARSH} BPF_K are still missing
the optimization.
This patch enables the zero-extension optimization for these remaining
cases.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200506000320.28965-2-luke.r.nels@gmail.com
The existing code in emit_call on RV64 checks that the PC-relative offset
to the function fits in 32 bits before calling emit_jump_and_link to emit
an auipc+jalr pair. However, this check is incorrect because offsets in
the range [2^31 - 2^11, 2^31 - 1] cannot be encoded using auipc+jalr on
RV64 (see discussion [1]). The RISC-V spec has recently been updated
to reflect this fact [2, 3].
This patch fixes the problem by moving the check on the offset into
emit_jump_and_link and modifying it to the correct range of encodable
offsets, which is [-2^31 - 2^11, 2^31 - 2^11). This also enforces the
check on the offset to other uses of emit_jump_and_link (e.g., BPF_JA)
as well.
Currently, this bug is unlikely to be triggered, because the memory
region from which JITed images are allocated is close enough to kernel
text for the offsets to not become too large; and because the bounds on
BPF program size are small enough. This patch prevents this problem from
becoming an issue if either of these change.
[1]: https://groups.google.com/a/groups.riscv.org/forum/#!topic/isa-dev/bwWFhBnnZFQ
[2]: b1e42e09ac
[3]: 4c1b2066eb
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200406221604.18547-1-luke.r.nels@gmail.com
This patch factors out code that can be used by both the RV64 and RV32
BPF JITs to a common bpf_jit.h and bpf_jit_core.c.
Move struct definitions and macro-like functions to header. Rename
rv_sb_insn/rv_uj_insn to rv_b_insn/rv_j_insn to match the RISC-V
specification.
Move reusable functions emit_body() and bpf_int_jit_compile() to
bpf_jit_core.c with minor simplifications. Rename emit_insn() and
build_{prologue,epilogue}() to be prefixed with "bpf_jit_" as they are
no longer static.
Rename bpf_jit_comp.c to bpf_jit_comp64.c to be more explicit.
Co-developed-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Acked-by: Björn Töpel <bjorn.topel@gmail.com>
Link: https://lore.kernel.org/bpf/20200305050207.4159-2-luke.r.nels@gmail.com
