git: 836fcf84616a - stable/13 - i386 copyout_fast: improve detection of a fault on accessing userspace

The branch stable/13 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=836fcf84616a45c5c026610ee813996c44cdb9ba

commit 836fcf84616a45c5c026610ee813996c44cdb9ba
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2022-08-09 00:56:54 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2022-08-31 01:20:27 +0000

    i386 copyout_fast: improve detection of a fault on accessing userspace
    
    (cherry picked from commit 95f773e59482b1a3462d2fe3901532d51fb053b3)
---
 sys/i386/i386/copyout_fast.s | 16 ++++++++--------
 sys/i386/i386/exception.s    | 32 ++++++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/sys/i386/i386/copyout_fast.s b/sys/i386/i386/copyout_fast.s
index 715952f5fe20..d1d17f775872 100644
--- a/sys/i386/i386/copyout_fast.s
+++ b/sys/i386/i386/copyout_fast.s
@@ -93,7 +93,7 @@ ENTRY(copyout_fast)
 	popl	%ecx
 	popl	%edi
 	popl	%esi
-	rep; movsb
+pf_x1:	rep; movsb
 
 	movl	%ebx,%cr3
 	movl	%eax,%esp
@@ -150,7 +150,7 @@ ENTRY(copyin_fast)
 	popl	%ecx
 	popl	%edi
 	popl	%esi
-	rep; movsb
+pf_x2:	rep; movsb
 
 	movl	%ebx,%cr3
 
@@ -197,7 +197,7 @@ ENTRY(fueword_fast)
 	cli
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
-	movl	(%ecx),%eax
+pf_x3:	movl	(%ecx),%eax
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
@@ -226,7 +226,7 @@ ENTRY(fuword16_fast)
 	cli
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
-	movzwl	(%ecx),%eax
+pf_x4:	movzwl	(%ecx),%eax
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
@@ -252,7 +252,7 @@ ENTRY(fubyte_fast)
 	cli
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
-	movzbl	(%ecx),%eax
+pf_x5:	movzbl	(%ecx),%eax
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
@@ -291,7 +291,7 @@ ENTRY(suword_fast)
 	cli
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
-	movl	%edi,(%ecx)
+pf_x6:	movl	%edi,(%ecx)
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
@@ -319,7 +319,7 @@ ENTRY(suword16_fast)
 	cli
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
-	movw	%di,(%ecx)
+pf_x7:	movw	%di,(%ecx)
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
@@ -348,7 +348,7 @@ ENTRY(subyte_fast)
 	movl	PCPU(TRAMPSTK),%esp
 	movl	%eax,%cr3
 	movl	%edi,%eax
-	movb	%al,(%ecx)
+pf_x8:	movb	%al,(%ecx)
 	movl	%ebx,%cr3
 	movl	%esi,%esp
 	sti
diff --git a/sys/i386/i386/exception.s b/sys/i386/i386/exception.s
index 4e806e8b3bd9..ac687aa502fb 100644
--- a/sys/i386/i386/exception.s
+++ b/sys/i386/i386/exception.s
@@ -133,17 +133,41 @@ IDTVEC(prot)
 	jmp	irettraps
 IDTVEC(page)
 	testl	$PSL_VM, TF_EFLAGS-TF_ERR(%esp)
-	jnz	1f
+	jnz	4f
 	testb	$SEL_RPL_MASK, TF_CS-TF_ERR(%esp)
-	jnz	1f
+	jnz	4f
 	cmpl	$PMAP_TRM_MIN_ADDRESS, TF_EIP-TF_ERR(%esp)
-	jb	1f
+	jb	4f
+	pushl	%eax
+	movl	TF_EIP-TF_ERR+4(%esp), %eax
+	addl	$1f, %eax
+	call	5f
+1:	cmpl	$pf_x1, %eax
+	je	2f
+	cmpl	$pf_x2, %eax
+	je	2f
+	cmpl	$pf_x3, %eax
+	je	2f
+	cmpl	$pf_x4, %eax
+	je	2f
+	cmpl	$pf_x5, %eax
+	je	2f
+	cmpl	$pf_x6, %eax
+	je	2f
+	cmpl	$pf_x7, %eax
+	je	2f
+	cmpl	$pf_x8, %eax
+	jne	3f
+2:	popl	%eax
 	movl	%ebx, %cr3
 	movl	%edx, TF_EIP-TF_ERR(%esp)
 	addl	$4, %esp
 	iret
-1:	pushl	$T_PAGEFLT
+3:	popl	%eax
+4:	pushl	$T_PAGEFLT
 	jmp	alltraps
+5:	subl	(%esp), %eax
+	retl
 IDTVEC(rsvd_pti)
 IDTVEC(rsvd)
 	pushl $0; TRAP(T_RESERVED)