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authorLai Jiangshan <jiangshan.ljs@antgroup.com>2022-04-21 22:10:48 +0800
committerBorislav Petkov <bp@suse.de>2022-05-03 11:18:59 +0200
commit0aca53c6b522f8d6e2681ca875acbbe105f5fdcf (patch)
tree4ccbb959b3336d3b7d84f385e290175c6c32b4f2
parent672c0c5173427e6b3e2a9bbb7be51ceeec78093a (diff)
downloadlinux-0aca53c6b522f8d6e2681ca875acbbe105f5fdcf.tar.bz2
x86/traps: Use pt_regs directly in fixup_bad_iret()
Always stash the address error_entry() is going to return to, in %r12 and get rid of the void *error_entry_ret; slot in struct bad_iret_stack which was supposed to account for it and pt_regs pushed on the stack. After this, both fixup_bad_iret() and sync_regs() can work on a struct pt_regs pointer directly. [ bp: Rewrite commit message, touch ups. ] Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lore.kernel.org/r/20220503032107.680190-2-jiangshanlai@gmail.com
-rw-r--r--arch/x86/entry/entry_64.S5
-rw-r--r--arch/x86/include/asm/traps.h2
-rw-r--r--arch/x86/kernel/traps.c19
3 files changed, 12 insertions, 14 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 73d958522b6a..ecbfca3cc18c 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1061,9 +1061,12 @@ 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.
*/
- mov %rsp, %rdi
+ popq %r12 /* save return addr in %12 */
+ movq %rsp, %rdi /* arg0 = pt_regs pointer */
call fixup_bad_iret
mov %rax, %rsp
+ ENCODE_FRAME_POINTER
+ pushq %r12
jmp .Lerror_entry_from_usermode_after_swapgs
SYM_CODE_END(error_entry)
diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 35317c5c551d..47ecfff2c83d 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -13,7 +13,7 @@
#ifdef CONFIG_X86_64
asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs);
asmlinkage __visible notrace
-struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s);
+struct pt_regs *fixup_bad_iret(struct pt_regs *bad_regs);
void __init trap_init(void);
asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *eregs);
#endif
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1563fb995005..4167215333fd 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -892,14 +892,10 @@ sync:
}
#endif
-struct bad_iret_stack {
- void *error_entry_ret;
- struct pt_regs regs;
-};
-
-asmlinkage __visible noinstr
-struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
+asmlinkage __visible noinstr struct pt_regs *fixup_bad_iret(struct pt_regs *bad_regs)
{
+ struct pt_regs tmp, *new_stack;
+
/*
* This is called from entry_64.S early in handling a fault
* caused by a bad iret to user mode. To handle the fault
@@ -908,19 +904,18 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
* just below the IRET frame) and we want to pretend that the
* exception came from the IRET target.
*/
- struct bad_iret_stack tmp, *new_stack =
- (struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
+ new_stack = (struct pt_regs *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
/* Copy the IRET target to the temporary storage. */
- __memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
+ __memcpy(&tmp.ip, (void *)bad_regs->sp, 5*8);
/* Copy the remainder of the stack from the current stack. */
- __memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
+ __memcpy(&tmp, bad_regs, offsetof(struct pt_regs, ip));
/* Update the entry stack */
__memcpy(new_stack, &tmp, sizeof(tmp));
- BUG_ON(!user_mode(&new_stack->regs));
+ BUG_ON(!user_mode(new_stack));
return new_stack;
}
#endif