Commit f5a376ed authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_entry_for_v5.11_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fix from Borislav Petkov:
 "A single fix for objtool to generate proper unwind info for newer
  toolchains which do not generate section symbols anymore. And a
  cleanup ontop.

  This was originally going to go during the next merge window but
  people can already trigger a build error with binutils-2.36 which
  doesn't emit section symbols - something which objtool relies on - so
  let's expedite it"

* tag 'x86_entry_for_v5.11_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry: Remove put_ret_addr_in_rdi THUNK macro argument
  x86/entry: Emit a symbol for register restoring thunk
parents 17b756d0 0bab9cb2

Documentation/asm-annotations.rst

+5 −0
Original line number Diff line number Diff line
@@ -100,6 +100,11 @@ Instruction Macros 
~~~~~~~~~~~~~~~~~~

This section covers ``SYM_FUNC_*`` and ``SYM_CODE_*`` enumerated above.



``objtool`` requires that all code must be contained in an ELF symbol. Symbol

names that have a ``.L`` prefix do not emit symbol table entries. ``.L``

prefixed symbols can be used within a code region, but should be avoided for

denoting a range of code via ``SYM_*_START/END`` annotations.



* ``SYM_FUNC_START`` and ``SYM_FUNC_START_LOCAL`` are supposed to be **the

  most frequent markings**. They are used for functions with standard calling

  conventions -- global and local. Like in C, they both align the functions to

arch/x86/entry/thunk_64.S

+5 −10
Original line number Diff line number Diff line
@@ -10,7 +10,7 @@ 
#include <asm/export.h>



	/* rdi:	arg1 ... normal C conventions. rax is saved/restored. */

	.macro THUNK name, func, put_ret_addr_in_rdi=0

	.macro THUNK name, func

SYM_FUNC_START_NOALIGN(\name)

	pushq %rbp

	movq %rsp, %rbp
@@ -25,13 +25,8 @@ SYM_FUNC_START_NOALIGN(\name) 
	pushq %r10

	pushq %r11



	.if \put_ret_addr_in_rdi

	/* 8(%rbp) is return addr on stack */

	movq 8(%rbp), %rdi

	.endif



	call \func

	jmp  .L_restore

	jmp  __thunk_restore

SYM_FUNC_END(\name)

	_ASM_NOKPROBE(\name)

	.endm
@@ -44,7 +39,7 @@ SYM_FUNC_END(\name) 
#endif



#ifdef CONFIG_PREEMPTION

SYM_CODE_START_LOCAL_NOALIGN(.L_restore)

SYM_CODE_START_LOCAL_NOALIGN(__thunk_restore)

	popq %r11

	popq %r10

	popq %r9
@@ -56,6 +51,6 @@ SYM_CODE_START_LOCAL_NOALIGN(.L_restore) 
	popq %rdi

	popq %rbp

	ret

	_ASM_NOKPROBE(.L_restore)

SYM_CODE_END(.L_restore)

	_ASM_NOKPROBE(__thunk_restore)

SYM_CODE_END(__thunk_restore)

#endif

include/linux/linkage.h

+5 −0
Original line number Diff line number Diff line
@@ -178,6 +178,11 @@ 
 * Objtool generates debug info for both FUNC & CODE, but needs special

 * annotations for each CODE's start (to describe the actual stack frame).

 *

 * Objtool requires that all code must be contained in an ELF symbol. Symbol

 * names that have a  .L prefix do not emit symbol table entries. .L

 * prefixed symbols can be used within a code region, but should be avoided for

 * denoting a range of code via ``SYM_*_START/END`` annotations.

 *

 * ALIAS -- does not generate debug info -- the aliased function will

 */