diff options
| author | Puranjay Mohan <puranjay@kernel.org> | 2025-10-30 12:17:14 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-10-31 11:20:53 -0700 |
| commit | be708ed300e1ebd32978b4092b909f0d9be0958f (patch) | |
| tree | e24714cf4ae07f7c883b6e031b1ada8ba69043e3 | |
| parent | 14a7f2392f42bbb71c1a5ea68930006221fcd80a (diff) | |
bpf/arm64: Fix BPF_ST into arena memory
The arm64 JIT supports BPF_ST with BPF_PROBE_MEM32 (arena) by using the
tmp2 register to hold the dst + arena_vm_base value and using tmp2 as the
new dst register. But this is broken because in case is_lsi_offset()
returns false the tmp2 will be clobbered by emit_a64_mov_i(1, tmp2, off,
ctx); and hence the emitted store instruction will be of the form:
strb w10, [x11, x11]
Fix this by using the third temporary register to hold the dst +
arena_vm_base.
Fixes: 339af577ec05 ("bpf: Add arm64 JIT support for PROBE_MEM32 pseudo instructions.")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20251030121715.55214-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index ab83089c3d8f..0c9a50a1e73e 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1213,6 +1213,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, u8 src = bpf2a64[insn->src_reg]; const u8 tmp = bpf2a64[TMP_REG_1]; const u8 tmp2 = bpf2a64[TMP_REG_2]; + const u8 tmp3 = bpf2a64[TMP_REG_3]; const u8 fp = bpf2a64[BPF_REG_FP]; const u8 arena_vm_base = bpf2a64[ARENA_VM_START]; const u8 priv_sp = bpf2a64[PRIVATE_SP]; @@ -1757,8 +1758,8 @@ emit_cond_jmp: case BPF_ST | BPF_PROBE_MEM32 | BPF_W: case BPF_ST | BPF_PROBE_MEM32 | BPF_DW: if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) { - emit(A64_ADD(1, tmp2, dst, arena_vm_base), ctx); - dst = tmp2; + emit(A64_ADD(1, tmp3, dst, arena_vm_base), ctx); + dst = tmp3; } if (dst == fp) { dst_adj = ctx->priv_sp_used ? priv_sp : A64_SP; |