linux/tools/objtool
Petr Pavlu 79cd2a1122 x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG
The linker script arch/x86/kernel/vmlinux.lds.S matches the thunk
sections ".text.__x86.*" from arch/x86/lib/retpoline.S as follows:

  .text {
    [...]
    TEXT_TEXT
    [...]
    __indirect_thunk_start = .;
    *(.text.__x86.*)
    __indirect_thunk_end = .;
    [...]
  }

Macro TEXT_TEXT references TEXT_MAIN which normally expands to only
".text". However, with CONFIG_LTO_CLANG, TEXT_MAIN becomes
".text .text.[0-9a-zA-Z_]*" which wrongly matches also the thunk
sections. The output layout is then different than expected. For
instance, the currently defined range [__indirect_thunk_start,
__indirect_thunk_end] becomes empty.

Prevent the problem by using ".." as the first separator, for example,
".text..__x86.indirect_thunk". This pattern is utilized by other
explicit section names which start with one of the standard prefixes,
such as ".text" or ".data", and that need to be individually selected in
the linker script.

  [ nathan: Fix conflicts with SRSO and fold in fix issue brought up by
    Andrew Cooper in post-review:
    https://lore.kernel.org/20230803230323.1478869-1-andrew.cooper3@citrix.com ]

Fixes: dc5723b02e ("kbuild: add support for Clang LTO")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com
2023-08-14 11:44:19 +02:00
..
arch x86/srso: Add a Speculative RAS Overflow mitigation 2023-07-27 11:07:14 +02:00
Documentation objtool: Move noreturn function list to separate file 2023-05-16 06:31:55 -07:00
include/objtool objtool: Get rid of reloc->rel[a] 2023-06-07 10:03:26 -07:00
.gitignore objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
Build objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
builtin-check.c objtool: Add verbose option for disassembling affected functions 2023-05-16 06:31:51 -07:00
check.c x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG 2023-08-14 11:44:19 +02:00
elf.c objtool: initialize all of struct elf 2023-07-10 09:52:28 +02:00
Makefile objtool: Fix HOSTCC flag usage 2023-02-01 09:15:18 -08:00
noreturns.h objtool: Remove btrfs_assertfail() from the noreturn exceptions list 2023-06-29 17:27:47 -07:00
objtool.c objtool: Remove instruction::list 2023-02-23 09:21:44 +01:00
orc_dump.c x86,objtool: Split UNWIND_HINT_EMPTY in two 2023-03-23 23:18:58 +01:00
orc_gen.c objtool: Add elf_create_section_pair() 2023-06-07 10:03:17 -07:00
special.c objtool: Get rid of reloc->addend 2023-06-07 10:03:23 -07:00
sync-check.sh objtool: Add objtool_types.h 2023-03-23 23:18:56 +01:00
weak.c objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00