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Subject[PATCH v2 bpf-next 4/7] bpf: add a pointer of bpf_binary_header to bpf_prog
Date
With sub page allocation, we cannot simply use bpf_func & PAGE_MASK to
find the bpf_binary_header. Add a pointer to struct bpf_prog to avoid
this logic.

Use this point for x86_64. If the pointer is not set by the jit engine,
fall back to original logic.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
arch/x86/net/bpf_jit_comp.c | 2 ++
include/linux/filter.h | 10 ++++++++--
2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 4bbcded07415..2231d483f82c 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2304,6 +2304,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
if (header)
bpf_jit_binary_free(header);
prog = orig_prog;
+ header = NULL;
goto out_addrs;
}
if (image) {
@@ -2371,6 +2372,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
if (tmp_blinded)
bpf_jit_prog_release_other(prog, prog == orig_prog ?
tmp : orig_prog);
+ prog->hdr = header;
return prog;
}

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 6d73d89c99a4..b5c7e12f7675 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -584,6 +584,7 @@ struct bpf_prog {
const struct bpf_insn *insn);
struct bpf_prog_aux *aux; /* Auxiliary fields */
struct sock_fprog_kern *orig_prog; /* Original BPF program */
+ struct bpf_binary_header *hdr;
/* Instructions for interpreter */
union {
DECLARE_FLEX_ARRAY(struct sock_filter, insns);
@@ -893,9 +894,14 @@ static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
static inline struct bpf_binary_header *
bpf_jit_binary_hdr(const struct bpf_prog *fp)
{
- unsigned long real_start = (unsigned long)fp->bpf_func;
- unsigned long addr = real_start & PAGE_MASK;
+ unsigned long real_start;
+ unsigned long addr;

+ if (fp->hdr)
+ return fp->hdr;
+
+ real_start = (unsigned long)fp->bpf_func;
+ addr = real_start & PAGE_MASK;
return (void *)addr;
}

--
2.30.2
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