Commit e55a7325 authored Jun 27, 2019 by Josh Poimboeuf Committed by Ingo Molnar Jul 09, 2019

bpf: Fix ORC unwinding in non-JIT BPF code



Objtool previously ignored ___bpf_prog_run() because it didn't understand
the jump table.  This resulted in the ORC unwinder not being able to unwind
through non-JIT BPF code.

Now that objtool knows how to read jump tables, remove the whitelist and
annotate the jump table so objtool can recognize it.

Also add an additional "const" to the jump table definition to clarify that
the text pointers are constant.  Otherwise GCC sets the section writable
flag and the assembler spits out warnings.

Fixes: d15d3568 ("perf/x86: Make perf callchains work without CONFIG_FRAME_POINTER")
Reported-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kairui Song <kasong@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lkml.kernel.org/r/881939122b88f32be4c374d248c09d7527a87e35.1561685471.git.jpoimboe@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 87b512de

kernel/bpf/core.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1299,7 +1299,7 @@ static u64 ___bpf_prog_run(u64 regs, const struct bpf_insn insn, u64 *stack)
		{
		#define BPF_INSN_2_LBL(x, y) [BPF_##x \| BPF_##y] = &&x##_##y
		#define BPF_INSN_3_LBL(x, y, z) [BPF_##x \| BPF_##y \| BPF_##z] = &&x##_##y##_##z
		static const void *jumptable[256] = {
		static const void * const jumptable[256] __annotate_jump_table = {
		[0 ... 255] = &&default_label,
		/* Now overwrite non-defaults ... */
		BPF_INSN_MAP(BPF_INSN_2_LBL, BPF_INSN_3_LBL),
		@@ -1558,7 +1558,6 @@ out:
		BUG_ON(1);
		return 0;
		}
		STACK_FRAME_NON_STANDARD(___bpf_prog_run); /* jump table */

		#define PROG_NAME(stack_size) __bpf_prog_run##stack_size
		#define DEFINE_BPF_PROG_RUN(stack_size) \

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