[lkml]   [2020]   [Apr]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH v2 04/11] x86/entry/64: Fix unwind hints in __switch_to_asm()
UNWIND_HINT_FUNC has some limitations: specifically, it doesn't reset
all the registers to undefined. This causes objtool to get confused
about the RBP push in __switch_to_asm(), resulting in bad ORC data.

While __switch_to_asm() does do some stack magic, it's otherwise a
normal callable-from-C function, so just annotate it as a function,
which makes objtool happy and allows it to produces the correct hints

Fixes: 8c1f75587a18 ("x86/entry/64: Add unwind hint annotations")
Signed-off-by: Josh Poimboeuf <>
Reviewed-by: Miroslav Benes <>
arch/x86/entry/entry_64.S | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 6b0d679efd6b..34a588950fe1 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -279,8 +279,7 @@ SYM_CODE_END(entry_SYSCALL_64)
* %rdi: prev task
* %rsi: next task
* Save callee-saved registers
* This must match the order in inactive_task_frame
@@ -321,7 +320,7 @@ SYM_CODE_START(__switch_to_asm)
popq %rbp

jmp __switch_to

* A newly forked process directly context switches into this address.
 \ /
  Last update: 2020-04-25 12:04    [W:0.112 / U:1.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site