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[bpf,1/3] bpf: show real jited prog address in /proc/kallsyms

Message ID 20181101070058.2760251-2-songliubraving@fb.com
State Changes Requested, archived
Delegated to: BPF Maintainers
Headers show
Series show more accurrate bpf program address | expand

Commit Message

Song Liu Nov. 1, 2018, 7 a.m. UTC
Currently, /proc/kallsyms shows page address of jited bpf program. This
is not ideal for detailed profiling (find hot instructions from stack
traces). This patch replaces the page address with real prog start

Signed-off-by: Song Liu <songliubraving@fb.com>
 kernel/bpf/core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
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diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 6377225b2082..1a796e0799ec 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -553,7 +553,6 @@  bool is_bpf_text_address(unsigned long addr)
 int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		    char *sym)
-	unsigned long symbol_start, symbol_end;
 	struct bpf_prog_aux *aux;
 	unsigned int it = 0;
 	int ret = -ERANGE;
@@ -566,10 +565,9 @@  int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		if (it++ != symnum)
-		bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end);
 		bpf_get_prog_name(aux->prog, sym);
-		*value = symbol_start;
+		*value = (unsigned long)aux->prog->bpf_func;
 		*type  = BPF_SYM_ELF_TYPE;
 		ret = 0;