Attachment 72752 Details for Bug 156580

[patch] 2.6 fix

em64t-sysret-check (text/plain), 1.42 KB, created by Andreas Kleen on 2006-03-14 12:21:00 UTC

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Creator: Andreas Kleen

Created: 2006-03-14 12:21:00 UTC

Size: 1.42 KB

patch

obsolete

>Index: linux/arch/x86_64/kernel/entry.S
>===================================================================
>--- linux.orig/arch/x86_64/kernel/entry.S
>+++ linux/arch/x86_64/kernel/entry.S
>@@ -225,8 +225,13 @@ sysret_check:		
> 	/*CFI_REGISTER	rflags,r11*/
> 	movq	%gs:pda_oldrsp,%rsp
> 	swapgs
>+sysret_label:
> 	sysretq
> 
>+	.section __ex_table,"a"
>+	.quad sysret_label,bad_iret	
>+	.previous
>+
> 	/* Handle reschedules */
> 	/* edx:	work, edi: workmask */	
> sysret_careful:
>@@ -776,11 +781,10 @@ error_exit:		
> 
> error_kernelspace:
> 	incl %ebx
>-       /* There are two places in the kernel that can potentially fault with
>-          usergs. Handle them here. The exception handlers after
>-	   iret run with kernel gs again, so don't set the user space flag.
>-	   B stepping K8s sometimes report an truncated RIP for IRET 
>-	   exceptions returning to compat mode. Check for these here too. */
>+       /* There are a few places in the kernel that can potentially fault with
>+          usergs. Handle them here. 
>+	  B stepping K8s sometimes report an truncated RIP for IRET 
>+	  exceptions returning to compat mode. Check for these here too. */
> 	leaq iret_label(%rip),%rbp
> 	cmpq %rbp,RIP(%rsp) 
> 	je   error_swapgs
>@@ -789,6 +793,8 @@ error_kernelspace:
> 	je   error_swapgs
> 	cmpq $gs_change,RIP(%rsp)
>         je   error_swapgs
>+	cmpq $sysret_label,RIP(%rsp)
>+	je   error_swapgs
> 	jmp  error_sti
> 	
>        /* Reload gs selector with exception handling */

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