From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Date: Thu, 21 Apr 2022 22:10:50 +0800
Subject: x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()
Git-commit: ee774dac0da1543376a69fd90840af6aa86879b3
Patch-mainline: 5.19-rc1
References: git-fixes
The macro idtentry() (through idtentry_body()) calls error_entry()
unconditionally even on XENPV. But XENPV needs to only push and clear
regs.
PUSH_AND_CLEAR_REGS in error_entry() makes the stack not return to its
original place when the function returns, which means it is not possible
to convert it to a C function.
Carve out PUSH_AND_CLEAR_REGS out of error_entry() and into a separate
function and call it before error_entry() in order to avoid calling
error_entry() on XENPV.
It will also allow for error_entry() to be converted to C code that can
use inlined sync_regs() and save a function call.
[ bp: Massage commit message. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220503032107.680190-4-jiangshanlai@gmail.com
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
arch/x86/entry/entry_64.S | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -315,6 +315,14 @@ SYM_CODE_END(ret_from_fork)
#endif
.endm
+/* Save all registers in pt_regs */
+SYM_CODE_START_LOCAL(push_and_clear_regs)
+ UNWIND_HINT_FUNC
+ PUSH_AND_CLEAR_REGS save_ret=1
+ ENCODE_FRAME_POINTER 8
+ RET
+SYM_CODE_END(push_and_clear_regs)
+
/**
* idtentry_body - Macro to emit code calling the C function
* @cfunc: C function to be called
@@ -322,6 +330,9 @@ SYM_CODE_END(ret_from_fork)
*/
.macro idtentry_body cfunc has_error_code:req
+ call push_and_clear_regs
+ UNWIND_HINT_REGS
+
call error_entry
movq %rax, %rsp /* switch to the task stack if from userspace */
ENCODE_FRAME_POINTER
@@ -965,13 +976,11 @@ SYM_CODE_START_LOCAL(paranoid_exit)
SYM_CODE_END(paranoid_exit)
/*
- * Save all registers in pt_regs, and switch GS if needed.
+ * Switch GS and CR3 if needed.
*/
SYM_CODE_START_LOCAL(error_entry)
UNWIND_HINT_FUNC
cld
- PUSH_AND_CLEAR_REGS save_ret=1
- ENCODE_FRAME_POINTER 8
testb $3, CS+8(%rsp)
jz .Lerror_kernelspace