Hello Christophe,
Thanks for the review.
On 07/04/23 11:31 am, Christophe Leroy wrote:
Le 06/04/2023 à 09:35, Hari Bathini a écrit :
Since commit 85e031154c7c ("powerpc/bpf: Perform complete extra passes
to update addresses"), two additional passes are performed to avoid
space and CPU time wastage on powerpc. But these extra passes led to
WARN_ON_ONCE() hits in bpf_add_extable_entry(). Fix it by not adding
extable entries during the extra pass.
Are you sure this change is correct ?
Actually, I was in two minds about that owing to commit 04c04205bc35
("bpf powerpc: Remove extra_pass from bpf_jit_build_body()").
During the extra pass the code can get shrinked or expanded (within the
limits of the size of the preliminary pass). Shouldn't extable entries
be populated during the last pass ?
Unlikely, but the intention there was to eliminate a regression in case
extra_pass ends up being 'false' always in any subsequent change.
- Hari
Fixes: 85e031154c7c ("powerpc/bpf: Perform complete extra passes to update addresses")
Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
---
arch/powerpc/net/bpf_jit_comp32.c | 2 +-
arch/powerpc/net/bpf_jit_comp64.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
index 7f91ea064c08..e788b1fbeee6 100644
--- a/arch/powerpc/net/bpf_jit_comp32.c
+++ b/arch/powerpc/net/bpf_jit_comp32.c
@@ -977,7 +977,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
if (size != BPF_DW && !fp->aux->verifier_zext)
EMIT(PPC_RAW_LI(dst_reg_h, 0));
- if (BPF_MODE(code) == BPF_PROBE_MEM) {
+ if (BPF_MODE(code) == BPF_PROBE_MEM && !extra_pass) {
int insn_idx = ctx->idx - 1;
int jmp_off = 4;
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 8dd3cabaa83a..1cc2777ec846 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -921,7 +921,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
if (size != BPF_DW && insn_is_zext(&insn[i + 1]))
addrs[++i] = ctx->idx * 4;
- if (BPF_MODE(code) == BPF_PROBE_MEM) {
+ if (BPF_MODE(code) == BPF_PROBE_MEM && !extra_pass) {
ret = bpf_add_extable_entry(fp, image, pass, ctx, ctx->idx - 1,
4, dst_reg);
if (ret)
