Commit-ID: 39853cc0cdcf1b11f00f7f81e2f515a4d68ed209 Gitweb: http://git.kernel.org/tip/39853cc0cdcf1b11f00f7f81e2f515a4d68ed209 Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> AuthorDate: Sun, 28 Feb 2016 22:22:37 -0600 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Mon, 29 Feb 2016 08:35:11 +0100 bpf: Mark __bpf_prog_run() stack frame as non-standard objtool reports the following false positive warnings: kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x5c: sibling call from callable instruction with changed frame pointer kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x60: function has unreachable instruction kernel/bpf/core.o: warning: objtool: __bpf_prog_run()+0x64: function has unreachable instruction [...] It's confused by the following dynamic jump instruction in __bpf_prog_run():: jmp *(%r12,%rax,8) which corresponds to the following line in the C code: goto *jumptable[insn->code]; There's no way for objtool to deterministically find all possible branch targets for a dynamic jump, so it can't verify this code. In this case the jumps all stay within the function, and there's nothing unusual going on related to the stack, so we can whitelist the function. Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Bernd Petrovitsch <bernd@xxxxxxxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Chris J Arges <chris.j.arges@xxxxxxxxxxxxx> Cc: Jiri Slaby <jslaby@xxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Michal Marek <mmarek@xxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxx> Cc: Pedro Alves <palves@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: live-patching@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/b90e6bf3fdbfb5c4cc1b164b965502e53cf48935.1456719558.git.jpoimboe@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- kernel/bpf/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 972d9a8..be0abf6 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -27,6 +27,7 @@ #include <linux/random.h> #include <linux/moduleloader.h> #include <linux/bpf.h> +#include <linux/frame.h> #include <asm/unaligned.h> @@ -649,6 +650,7 @@ load_byte: WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code); return 0; } +STACK_FRAME_NON_STANDARD(__bpf_prog_run); /* jump table */ bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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