diff options
| author | Puranjay Mohan <puranjay@kernel.org> | 2025-07-22 13:34:09 +0000 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2025-07-26 21:23:38 +0200 |
| commit | b114fcee766d5101eada1aca7bb5fd0a86c89b35 (patch) | |
| tree | 45b128b801b10442f085b33be3a2b182159b6dcd | |
| parent | b7b3500bd4eef2c3b5124ed195f26eb048407d9b (diff) | |
bpf, arm64: Fix fp initialization for exception boundary
In the ARM64 BPF JIT when prog->aux->exception_boundary is set for a BPF
program, find_used_callee_regs() is not called because for a program
acting as exception boundary, all callee saved registers are saved.
find_used_callee_regs() sets `ctx->fp_used = true;` when it sees FP
being used in any of the instructions.
For programs acting as exception boundary, ctx->fp_used remains false
even if frame pointer is used by the program and therefore, FP is not
set-up for such programs in the prologue. This can cause the kernel to
crash due to a pagefault.
Fix it by setting ctx->fp_used = true for exception boundary programs as
fp is always saved in such programs.
Fixes: 5d4fa9ec5643 ("bpf, arm64: Avoid blindly saving/restoring all callee-saved registers")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/bpf/20250722133410.54161-2-puranjay@kernel.org
| -rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 89b1b8c248c6..97ab651c0bd5 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -412,6 +412,7 @@ static void push_callee_regs(struct jit_ctx *ctx) emit(A64_PUSH(A64_R(23), A64_R(24), A64_SP), ctx); emit(A64_PUSH(A64_R(25), A64_R(26), A64_SP), ctx); emit(A64_PUSH(A64_R(27), A64_R(28), A64_SP), ctx); + ctx->fp_used = true; } else { find_used_callee_regs(ctx); for (i = 0; i + 1 < ctx->nr_used_callee_reg; i += 2) { |