diff options
| author | Lai Jiangshan <jiangshan.ljs@antgroup.com> | 2022-04-21 22:10:49 +0800 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-05-03 11:35:34 +0200 |
| commit | 520a7e80c96d655fbe4650d9cc985bd9d0443389 (patch) | |
| tree | d237a4f8d47361104ba0ac50d9561a013dabfaea /arch | |
| parent | 0aca53c6b522f8d6e2681ca875acbbe105f5fdcf (diff) | |
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
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index ecbfca3cc18c..ca3e99e08a44 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) |