On 12/04/26 3:44 am, [email protected] wrote:
From: Abhishek Dubey <[email protected]>
Ensure the dummy trampoline address field present between the OOL stub
and the long branch stub is 8-byte aligned, for memory compatibility
when content loaded to a register.
Reported-by: Hari Bathini <[email protected]>
Fixes: d243b62b7bd3 ("powerpc64/bpf: Add support for bpf trampolines")
Cc: [email protected]
Signed-off-by: Abhishek Dubey <[email protected]>
---
arch/powerpc/net/bpf_jit.h | 4 ++--
arch/powerpc/net/bpf_jit_comp.c | 34 ++++++++++++++++++++++++++-----
arch/powerpc/net/bpf_jit_comp64.c | 4 ++--
3 files changed, 33 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 7354e1d72f79..1184ad15d5a4 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -208,8 +208,8 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage,
struct codegen_context *
int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct
codegen_context *ctx,
u32 *addrs, int pass, bool extra_pass);
void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
-void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
-void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx);
+void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context
*ctx);
+void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct
codegen_context *ctx);
void bpf_jit_realloc_regs(struct codegen_context *ctx);
int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int
tmp_reg, long exit_addr);
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index a62a9a92b7b5..c255b30a37b0 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -49,11 +49,34 @@ asm (
" .popsection ;"
);
-void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx)
+void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct
codegen_context *ctx)
{
int ool_stub_idx, long_branch_stub_idx;
/*
+ * In the final pass, align the mis-aligned dummy_tramp_addr field
+ * in the fimage. The alignment NOP must appear before OOL stub,
+ * to make ool_stub_idx & long_branch_stub_idx constant from end.
+ *
+ * Need alignment NOP in following conditions:
+ *
I don't think I follow this table..
+ * OOL stub aligned CONFIG_PPC_FTRACE_OUT_OF_LINE Alignment NOP
+ * Y Y N
+ * Y N Y
Please help me understand why a NOP is needed here
+ * N Y Y
+ * N N N
and also, why a NOP isn't needed here..
- Hari
