x86/entry: Move thunk restore code into thunk functions

There's no need for both thunk functions to jump to the same shared
thunk restore code which lives outside the thunk function boundaries.
It disrupts i-cache locality and confuses objtool.  Keep it simple by
keeping each thunk's restore code self-contained within the function.

Fixes a bunch of false positive "missing __noreturn" warnings like:

  vmlinux.o: warning: objtool: do_arch_prctl_common+0xf4: preempt_schedule_thunk() is missing a __noreturn annotation

Fixes: fedb724c3db5 ("objtool: Detect missing __noreturn annotations")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202305281037.3PaI3tW4-lkp@intel.com/
Link: https://lore.kernel.org/r/46aa8aeb716f302e22e1673ae15ee6fe050b41f4.1685488050.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S
index 5e37f41e5f14d483283c8dc81f30463ff228be4b..27b5da2111ac9eb6d7681a79706f7e0c64a7f38b 100644 (file)
--- a/arch/x86/entry/thunk_64.S
+++ b/arch/x86/entry/thunk_64.S
@@ -26,17 +26,7 @@ SYM_FUNC_START(\name)
        pushq %r11
 
        call \func
-       jmp  __thunk_restore
-SYM_FUNC_END(\name)
-       _ASM_NOKPROBE(\name)
-       .endm
-
-       THUNK preempt_schedule_thunk, preempt_schedule
-       THUNK preempt_schedule_notrace_thunk, preempt_schedule_notrace
-       EXPORT_SYMBOL(preempt_schedule_thunk)
-       EXPORT_SYMBOL(preempt_schedule_notrace_thunk)
 
-SYM_CODE_START_LOCAL(__thunk_restore)
        popq %r11
        popq %r10
        popq %r9
@@ -48,5 +38,11 @@ SYM_CODE_START_LOCAL(__thunk_restore)
        popq %rdi
        popq %rbp
        RET
-       _ASM_NOKPROBE(__thunk_restore)
-SYM_CODE_END(__thunk_restore)
+SYM_FUNC_END(\name)
+       _ASM_NOKPROBE(\name)
+       .endm
+
+THUNK preempt_schedule_thunk, preempt_schedule
+THUNK preempt_schedule_notrace_thunk, preempt_schedule_notrace
+EXPORT_SYMBOL(preempt_schedule_thunk)
+EXPORT_SYMBOL(preempt_schedule_notrace_thunk)