From: "tip-bot2 for Lai Jiangshan" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Borislav Petkov <bp@suse.de>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: x86/asm] x86/entry: Switch the stack after error_entry() returns
Date: Tue, 03 May 2022 19:01:06 -0000 [thread overview]
Message-ID: <165160446663.4207.12038427447242778092.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20220503032107.680190-3-jiangshanlai@gmail.com>
The following commit has been merged into the x86/asm branch of tip:
Commit-ID: 520a7e80c96d655fbe4650d9cc985bd9d0443389
Gitweb: https://git.kernel.org/tip/520a7e80c96d655fbe4650d9cc985bd9d0443389
Author: Lai Jiangshan <jiangshan.ljs@antgroup.com>
AuthorDate: Thu, 21 Apr 2022 22:10:49 +08:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 03 May 2022 11:35:34 +02:00
x86/entry: Switch the stack after error_entry() returns
error_entry() calls fixup_bad_iret() before sync_regs() if it is a fault
from a bad IRET, to copy pt_regs to the kernel stack. It switches to the
kernel stack directly after sync_regs().
But error_entry() itself is also a function call, so it has to stash
the address it is going to return to, in %r12 which is unnecessarily
complicated.
Move the stack switching after error_entry() and get rid of the need to
handle the return address.
[ bp: Massage commit message. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220503032107.680190-3-jiangshanlai@gmail.com
---
arch/x86/entry/entry_64.S | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index ecbfca3..ca3e99e 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -326,6 +326,8 @@ SYM_CODE_END(ret_from_fork)
.macro idtentry_body cfunc has_error_code:req
call error_entry
+ movq %rax, %rsp /* switch to the task stack if from userspace */
+ ENCODE_FRAME_POINTER
UNWIND_HINT_REGS
movq %rsp, %rdi /* pt_regs pointer into 1st argument*/
@@ -1002,14 +1004,10 @@ SYM_CODE_START_LOCAL(error_entry)
/* We have user CR3. Change to kernel CR3. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
+ leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */
.Lerror_entry_from_usermode_after_swapgs:
/* Put us onto the real thread stack. */
- popq %r12 /* save return addr in %12 */
- movq %rsp, %rdi /* arg0 = pt_regs pointer */
call sync_regs
- movq %rax, %rsp /* switch stack */
- ENCODE_FRAME_POINTER
- pushq %r12
RET
/*
@@ -1041,6 +1039,7 @@ SYM_CODE_START_LOCAL(error_entry)
*/
.Lerror_entry_done_lfence:
FENCE_SWAPGS_KERNEL_ENTRY
+ leaq 8(%rsp), %rax /* return pt_regs pointer */
RET
.Lbstep_iret:
@@ -1061,12 +1060,9 @@ SYM_CODE_START_LOCAL(error_entry)
* Pretend that the exception came from user mode: set up pt_regs
* as if we faulted immediately after IRET.
*/
- popq %r12 /* save return addr in %12 */
- movq %rsp, %rdi /* arg0 = pt_regs pointer */
+ leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */
call fixup_bad_iret
- mov %rax, %rsp
- ENCODE_FRAME_POINTER
- pushq %r12
+ mov %rax, %rdi
jmp .Lerror_entry_from_usermode_after_swapgs
SYM_CODE_END(error_entry)
next prev parent reply other threads:[~2022-05-03 19:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-03 3:21 [PATCH V7 0/6] x86/entry: Clean up entry code Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 1/6] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] x86/traps: Use pt_regs directly " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 2/6] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-05-03 19:01 ` tip-bot2 for Lai Jiangshan [this message]
2022-05-03 3:21 ` [PATCH V7 3/6] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Lai Jiangshan
2022-05-03 7:23 ` Juergen Gross
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 4/6] x86/entry: Move cld to the start of idtentry macro Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] x86/entry: Move CLD to the start of the " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 5/6] x86/entry: Don't call error_entry() for XENPV Lai Jiangshan
2022-05-03 7:24 ` Juergen Gross
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
2022-05-03 3:21 ` [PATCH V7 6/6] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-05-03 19:01 ` [tip: x86/asm] " tip-bot2 for Lai Jiangshan
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