With previous commit, %rax is used to propagate tail_call_cnt pointer
instead of tail_call_cnt. So, LOAD_TAIL_CALL_CNT_PTR() is more accurate.
Signed-off-by: Leon Hwang <hffilwlqm@xxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 67fa337fc2e0c..4065bdcc5b2a4 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1142,7 +1142,7 @@ static void emit_shiftx(u8 **pprog, u32 dst_reg, u8 src_reg, bool is64, u8 op)
#define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp)))
/* mov rax, qword ptr [rbp - rounded_stack_depth - 8] */
-#define RESTORE_TAIL_CALL_CNT(stack) \
+#define LOAD_TAIL_CALL_CNT_PTR(stack) \
EMIT3_off32(0x48, 0x8B, 0x85, -round_up(stack, 8) - 8)
static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image,
@@ -1762,7 +1762,7 @@ st: if (is_imm8(insn->off))
func = (u8 *) __bpf_call_base + imm32;
if (tail_call_reachable) {
- RESTORE_TAIL_CALL_CNT(bpf_prog->aux->stack_depth);
+ LOAD_TAIL_CALL_CNT_PTR(bpf_prog->aux->stack_depth);
if (!imm32)
return -EINVAL;
offs = 7 + x86_call_depth_emit_accounting(&prog, func);
@@ -2558,7 +2558,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
* [ ... ]
* [ stack_arg2 ]
* RBP - arg_stack_off [ stack_arg1 ]
- * RSP [ tail_call_cnt ] BPF_TRAMP_F_TAIL_CALL_CTX
+ * RSP [ tail_call_cnt_ptr ] BPF_TRAMP_F_TAIL_CALL_CTX
*/
/* room for return value of orig_call or fentry prog */
@@ -2686,12 +2686,11 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
restore_regs(m, &prog, regs_off);
save_args(m, &prog, arg_stack_off, true);
- if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) {
- /* Before calling the original function, restore the
- * tail_call_cnt from stack to rax.
+ if (flags & BPF_TRAMP_F_TAIL_CALL_CTX)
+ /* Before calling the original function, load the
+ * tail_call_cnt_ptr to rax.
*/
- RESTORE_TAIL_CALL_CNT(stack_size);
- }
+ LOAD_TAIL_CALL_CNT_PTR(stack_size);
if (flags & BPF_TRAMP_F_ORIG_STACK) {
emit_ldx(&prog, BPF_DW, BPF_REG_6, BPF_REG_FP, 8);
@@ -2749,10 +2748,10 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
goto cleanup;
}
} else if (flags & BPF_TRAMP_F_TAIL_CALL_CTX) {
- /* Before running the original function, restore the
- * tail_call_cnt from stack to rax.
+ /* Before running the original function, load the
+ * tail_call_cnt_ptr to rax.
*/
- RESTORE_TAIL_CALL_CNT(stack_size);
+ LOAD_TAIL_CALL_CNT_PTR(stack_size);
}
/* restore return value of orig_call or fentry prog back into RAX */
--
2.42.1
