| Message ID | 20210809093437.876558-2-johan.almbladh@anyfinetworks.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | Fix MAX_TAIL_CALL_CNT handling in eBPF JITs | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 2 maintainers not CCed: linux-arm-kernel@lists.infradead.org linux@armlinux.org.uk |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 15 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index a951276f0547..200ae9d24205 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1180,12 +1180,12 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) /* tmp2[0] = array, tmp2[1] = index */ - /* if (tail_call_cnt > MAX_TAIL_CALL_CNT) + /* if (tail_call_cnt >= MAX_TAIL_CALL_CNT) * goto out; * tail_call_cnt++; */ - lo = (u32)MAX_TAIL_CALL_CNT; - hi = (u32)((u64)MAX_TAIL_CALL_CNT >> 32); + lo = (u32)(MAX_TAIL_CALL_CNT - 1); + hi = (u32)((u64)(MAX_TAIL_CALL_CNT - 1) >> 32); tc = arm_bpf_get_reg64(tcc, tmp, ctx); emit(ARM_CMP_I(tc[0], hi), ctx); _emit(ARM_COND_EQ, ARM_CMP_I(tc[1], lo), ctx);
Before, the eBPF JIT allowed up to MAX_TAIL_CALL_CNT + 1 tail calls. Now, precisely MAX_TAIL_CALL_CNT is allowed, which is in line with the behaviour of the interpreter. Verified with the test_bpf test suite on qemu-system-arm. Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com> --- arch/arm/net/bpf_jit_32.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)