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| author |   Björn Töpel <bjorn.topel@gmail.com> | 2019-05-21 15:46:22 +0200 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2019-05-23 15:53:55 +0200 |
| commit | fe121ee531d1362810bfd30f38a1b88b1d3d376c (patch) | |
| tree | 76cf52348e4c0ae2dae7e808c376d68b65b1e0df /arch/riscv | |
| parent | samples, bpf: suppress compiler warning (diff) | |
| download | linux-dev-fe121ee531d1362810bfd30f38a1b88b1d3d376c.tar.xz linux-dev-fe121ee531d1362810bfd30f38a1b88b1d3d376c.zip | |
bpf, riscv: clear target register high 32-bits for and/or/xor on ALU32
When using 32-bit subregisters (ALU32), the RISC-V JIT would not clear
the high 32-bits of the target register and therefore generate
incorrect code.
E.g., in the following code:
$ cat test.c
unsigned int f(unsigned long long a,
unsigned int b)
{
return (unsigned int)a & b;
}
$ clang-9 -target bpf -O2 -emit-llvm -S test.c -o - | \
llc-9 -mattr=+alu32 -mcpu=v3
.text
.file "test.c"
.globl f
.p2align 3
.type f,@function
f:
r0 = r1
w0 &= w2
exit
.Lfunc_end0:
.size f, .Lfunc_end0-f
The JIT would not clear the high 32-bits of r0 after the
and-operation, which in this case might give an incorrect return
value.
After this patch, that is not the case, and the upper 32-bits are
cleared.
Reported-by: Jiong Wang <jiong.wang@netronome.com>
Fixes: 2353ecc6f91f ("bpf, riscv: add BPF JIT for RV64G")
Signed-off-by: Björn Töpel <bjorn.topel@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'arch/riscv')
| -rw-r--r-- | arch/riscv/net/bpf_jit_comp.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/riscv/net/bpf_jit_comp.c b/arch/riscv/net/bpf_jit_comp.c index 80b12aa5e10d..e5c8d675bd6e 100644 --- a/arch/riscv/net/bpf_jit_comp.c +++ b/arch/riscv/net/bpf_jit_comp.c @@ -759,14 +759,20 @@ static int emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx, case BPF_ALU | BPF_AND | BPF_X: case BPF_ALU64 | BPF_AND | BPF_X: emit(rv_and(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_OR | BPF_X: case BPF_ALU64 | BPF_OR | BPF_X: emit(rv_or(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_XOR | BPF_X: case BPF_ALU64 | BPF_XOR | BPF_X: emit(rv_xor(rd, rd, rs), ctx); + if (!is64) + emit_zext_32(rd, ctx); break; case BPF_ALU | BPF_MUL | BPF_X: case BPF_ALU64 | BPF_MUL | BPF_X: |