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

Author: torvalds

Documentation/asm-annotations.rst

@@ -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

@@ -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

@@ -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
  */