Commit 1f552ce7 authored by Petr Pavlu's avatar Petr Pavlu Committed by sanglipeng
Browse files

x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG 

stable inclusion
from stable-v5.10.192
commit 26e3f7690cda4e241835ca80c3fbaf1b615a05a8
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I933RF

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=26e3f7690cda4e241835ca80c3fbaf1b615a05a8

--------------------------------

commit 79cd2a11 upstream.

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: dc5723b0 ("kbuild: add support for Clang LTO")
Signed-off-by: default avatarPetr Pavlu <petr.pavlu@suse.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarsanglipeng <sanglipeng1@jd.com>
parent d3cff34a

arch/x86/kernel/vmlinux.lds.S

+4 −4
Original line number Diff line number Diff line
@@ -134,7 +134,7 @@ SECTIONS 
		KPROBES_TEXT

		ALIGN_ENTRY_TEXT_BEGIN

#ifdef CONFIG_CPU_SRSO

		*(.text.__x86.rethunk_untrain)

		*(.text..__x86.rethunk_untrain)

#endif



		ENTRY_TEXT
@@ -145,7 +145,7 @@ SECTIONS 
		 * definition.

		 */

		. = srso_alias_untrain_ret | (1 << 2) | (1 << 8) | (1 << 14) | (1 << 20);

		*(.text.__x86.rethunk_safe)

		*(.text..__x86.rethunk_safe)

#endif

		ALIGN_ENTRY_TEXT_END

		SOFTIRQENTRY_TEXT
@@ -155,8 +155,8 @@ SECTIONS 


#ifdef CONFIG_RETPOLINE

		__indirect_thunk_start = .;

		*(.text.__x86.indirect_thunk)

		*(.text.__x86.return_thunk)

		*(.text..__x86.indirect_thunk)

		*(.text..__x86.return_thunk)

		__indirect_thunk_end = .;

#endif

	} :text =0xcccc

arch/x86/lib/retpoline.S

+4 −4
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
#include <asm/frame.h>

#include <asm/nops.h>



	.section .text.__x86.indirect_thunk

	.section .text..__x86.indirect_thunk



.macro RETPOLINE reg

	ANNOTATE_INTRA_FUNCTION_CALL
@@ -90,7 +90,7 @@ SYM_CODE_END(__x86_indirect_thunk_array) 
 * As a result, srso_alias_safe_ret() becomes a safe return.

 */

#ifdef CONFIG_CPU_SRSO

	.section .text.__x86.rethunk_untrain

	.section .text..__x86.rethunk_untrain



SYM_START(srso_alias_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE)

	UNWIND_HINT_FUNC
@@ -100,7 +100,7 @@ SYM_START(srso_alias_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) 
SYM_FUNC_END(srso_alias_untrain_ret)

__EXPORT_THUNK(srso_alias_untrain_ret)



	.section .text.__x86.rethunk_safe

	.section .text..__x86.rethunk_safe

#else

/* dummy definition for alternatives */

SYM_START(srso_alias_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE)
@@ -118,7 +118,7 @@ SYM_START(srso_alias_safe_ret, SYM_L_GLOBAL, SYM_A_NONE) 
	int3

SYM_FUNC_END(srso_alias_safe_ret)



	.section .text.__x86.return_thunk

	.section .text..__x86.return_thunk



SYM_CODE_START(srso_alias_return_thunk)

	UNWIND_HINT_FUNC

tools/objtool/check.c

+1 −1
Original line number Diff line number Diff line
@@ -368,7 +368,7 @@ static int decode_instructions(struct objtool_file *file) 


		if (!strcmp(sec->name, ".noinstr.text") ||

		    !strcmp(sec->name, ".entry.text") ||

		    !strncmp(sec->name, ".text.__x86.", 12))

		    !strncmp(sec->name, ".text..__x86.", 13))

			sec->noinstr = true;



		for (offset = 0; offset < sec->len; offset += insn->len) {