Peter Zijlstra 7117f16bf4 objtool: Fix ORC vs alternatives ... Jann reported that (for instance) entry_64.o:general_protection has very odd ORC data: 0000000000000f40 <general_protection>: #######sp:sp+8 bp:(und) type:iret end:0 f40: 90 nop #######sp:(und) bp:(und) type:call end:0 f41: 90 nop f42: 90 nop #######sp:sp+8 bp:(und) type:iret end:0 f43: e8 a8 01 00 00 callq 10f0 <error_entry> #######sp:sp+0 bp:(und) type:regs end:0 f48: f6 84 24 88 00 00 00 testb $0x3,0x88(%rsp) f4f: 03 f50: 74 00 je f52 <general_protection+0x12> f52: 48 89 e7 mov %rsp,%rdi f55: 48 8b 74 24 78 mov 0x78(%rsp),%rsi f5a: 48 c7 44 24 78 ff ff movq $0xffffffffffffffff,0x78(%rsp) f61: ff ff f63: e8 00 00 00 00 callq f68 <general_protection+0x28> f68: e9 73 02 00 00 jmpq 11e0 <error_exit> #######sp:(und) bp:(und) type:call end:0 f6d: 0f 1f 00 nopl (%rax) Note the entry at 0xf41. Josh found this was the result of commit: 764eef4b10 ("objtool: Rewrite alt->skip_orig") Due to the early return in validate_branch() we no longer set insn->cfi of the original instruction stream (the NOPs at 0xf41 and 0xf42) and we'll end up with the above weirdness. In other discussions we realized alternatives should be ORC invariant; that is, due to there being only a single ORC table, it must be valid for all alternatives. The easiest way to ensure this is to not allow any stack modifications in alternatives. When we enforce this latter observation, we get the property that the whole alternative must have the same CFI, which we can employ to fix the former report. Fixes: 764eef4b10 ("objtool: Rewrite alt->skip_orig") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191659.499074346@infradead.org		2020-04-30 20:14:31 +02:00
..
arch/x86	objtool: Constify arch_decode_instruction()	2020-04-23 08:34:18 +02:00
Documentation	objtool: Fix ORC vs alternatives	2020-04-30 20:14:31 +02:00
.gitignore	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
arch.h	objtool: Constify arch_decode_instruction()	2020-04-23 08:34:18 +02:00
Build	objtool: Optimize find_symbol_*() and read_symbols()	2020-03-25 18:28:29 +01:00
builtin-check.c	objtool: Implement noinstr validation	2020-04-22 10:53:50 +02:00
builtin-orc.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13	2019-05-21 11:28:45 +02:00
builtin.h	objtool: Implement noinstr validation	2020-04-22 10:53:50 +02:00
cfi.h	objtool: Fix !CFI insn_state propagation	2020-04-22 10:53:50 +02:00
check.c	objtool: Fix ORC vs alternatives	2020-04-30 20:14:31 +02:00
check.h	objtool: Uniquely identify alternative instruction groups	2020-04-30 20:14:31 +02:00
elf.c	objtool: Rename elf_read() to elf_open_read()	2020-04-23 08:34:18 +02:00
elf.h	objtool: Rename elf_read() to elf_open_read()	2020-04-23 08:34:18 +02:00
Makefile	objtool: Split out arch-specific CFI definitions	2020-04-22 10:53:49 +02:00
objtool.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13	2019-05-21 11:28:45 +02:00
orc.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13	2019-05-21 11:28:45 +02:00
orc_dump.c	objtool: Support Clang non-section symbols in ORC dump	2020-04-14 11:59:52 +02:00
orc_gen.c	objtool: Optimize !vmlinux.o again	2020-04-22 10:53:50 +02:00
special.c	objtool: Optimize read_sections()	2020-03-25 18:28:30 +01:00
special.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13	2019-05-21 11:28:45 +02:00
sync-check.sh	objtool: Silence build output	2020-01-22 07:54:34 +01:00
warn.h	objtool: Rename find_containing_func()	2020-03-25 18:28:29 +01:00