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powerpc64/bpf: do not increment tailcall count when prog is NULL

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Do not increment tailcall count, if tailcall did not succeed due to
missing BPF program.

Fixes: ce0761419f ("powerpc/bpf: Implement support for tail calls")
Cc: stable@vger.kernel.org
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260303181031.390073-2-hbathini@linux.ibm.com
This commit is contained in:
Hari Bathini 2026-03-03 23:40:25 +05:30 committed by Madhavan Srinivasan
parent db54c28702
commit 521bd39d9d
1 changed files with 21 additions and 18 deletions
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39
arch/powerpc/net/bpf_jit_comp64.c
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@ -522,9 +522,30 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o
/*
* tail_call_info++; <- Actual value of tcc here
* Writeback this updated value only if tailcall succeeds.
*/
EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), 1));
/* prog = array->ptrs[index]; */
EMIT(PPC_RAW_MULI(bpf_to_ppc(TMP_REG_2), b2p_index, 8));
EMIT(PPC_RAW_ADD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2), b2p_bpf_array));
EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),
offsetof(struct bpf_array, ptrs)));
/*
* if (prog == NULL)
* goto out;
*/
EMIT(PPC_RAW_CMPLDI(bpf_to_ppc(TMP_REG_2), 0));
PPC_BCC_SHORT(COND_EQ, out);
/* goto *(prog->bpf_func + prologue_size); */
EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),
offsetof(struct bpf_prog, bpf_func)));
EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_2), bpf_to_ppc(TMP_REG_2),
FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size));
EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_2)));
/*
* Before writing updated tail_call_info, distinguish if current frame
* is storing a reference to tail_call_info or actual tcc value in
@ -539,24 +560,6 @@ static int bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 o
/* Writeback updated value to tail_call_info */
EMIT(PPC_RAW_STD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_2), 0));
/* prog = array->ptrs[index]; */
EMIT(PPC_RAW_MULI(bpf_to_ppc(TMP_REG_1), b2p_index, 8));
EMIT(PPC_RAW_ADD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), b2p_bpf_array));
EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_array, ptrs)));
/*
* if (prog == NULL)
* goto out;
*/
EMIT(PPC_RAW_CMPLDI(bpf_to_ppc(TMP_REG_1), 0));
PPC_BCC_SHORT(COND_EQ, out);
/* goto *(prog->bpf_func + prologue_size); */
EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1), offsetof(struct bpf_prog, bpf_func)));
EMIT(PPC_RAW_ADDI(bpf_to_ppc(TMP_REG_1), bpf_to_ppc(TMP_REG_1),
FUNCTION_DESCR_SIZE + bpf_tailcall_prologue_size));
EMIT(PPC_RAW_MTCTR(bpf_to_ppc(TMP_REG_1)));
/* tear down stack, restore NVRs, ... */
bpf_jit_emit_common_epilogue(image, ctx);