swsusp: solving build issue leads to crash on x86-64

swsusp: solving build issue leads to crash on x86-64

[Pavel Machek]

Hi!

Do you remember that build issue, where you needed to added ', "aw"'
to make linker happy? Well, too late I found that it breaks swsusp in
quite a ugly way. Try it on x86-64: it works without "aw", breaks with
it.

I'm doing this for now. I'll probably just rewrite assemlby not to
require those variables, but understanding what went wrong there would
be welcome.

#       .section .data.nosave, "aw"
        .section .data.nosave
        .align 8
loop:
        .quad 0
loop2:
        .quad 0
        .previous

								Pavel

-- 
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!

swsusp: fix x86-64 [was Re: swsusp: solving build issue leads to crash on x86-64]

[Pavel Machek]

Hi!

I could not get accessing __nosave variables from assembly right, so I
simply eliminated memory accesses and cleaned up code at the same
time. Please apply,
								Pavel


> Do you remember that build issue, where you needed to added ', "aw"'
> to make linker happy? Well, too late I found that it breaks swsusp in
> quite a ugly way. Try it on x86-64: it works without "aw", breaks with
> it.
> 
> I'm doing this for now. I'll probably just rewrite assemlby not to
> require those variables, but understanding what went wrong there would
> be welcome.
> 
> #       .section .data.nosave, "aw"
>         .section .data.nosave
>         .align 8
> loop:
>         .quad 0
> loop2:
>         .quad 0
>         .previous


--- linux-mm/arch/x86_64/kernel/suspend_asm.S	2004-09-15 12:58:08.000000000 +0200
+++ linux64/arch/x86_64/kernel/suspend_asm.S	2004-09-16 22:20:21.000000000 +0200
@@ -39,29 +39,28 @@
 	/* set up cr3 */	
 	leaq	init_level4_pgt(%rip),%rax
 	subq	$__START_KERNEL_map,%rax
-	movq %rax,%cr3
+	movq	%rax,%cr3
 
 	movq	mmu_cr4_features(%rip), %rax
 	movq	%rax, %rdx
-	
 	andq	$~(1<<7), %rdx	# PGE
-	movq %rdx, %cr4;  # turn off PGE     
-	movq %cr3, %rcx;  # flush TLB        
-	movq %rcx, %cr3;                     
-	movq %rax, %cr4;  # turn PGE back on 
+	movq	%rdx, %cr4;  # turn off PGE     
+	movq	%cr3, %rcx;  # flush TLB        
+	movq	%rcx, %cr3;                     
+	movq	%rax, %cr4;  # turn PGE back on 
 
 	movl	nr_copy_pages(%rip), %eax
 	xorl	%ecx, %ecx
-	movq	$0, loop(%rip)
+	movq	$0, %r10
 	testl	%eax, %eax
-	je	.L108
+	jz	done
 .L105:
 	xorl	%esi, %esi
-	movq	$0, loop2(%rip)
+	movq	$0, %r11
 	jmp	.L104
 	.p2align 4,,7
-.L111:
-	movq	loop(%rip), %rcx
+copy_one_page:
+	movq	%r10, %rcx
 .L104:
 	movq	pagedir_nosave(%rip), %rdx
 	movq	%rcx, %rax
@@ -71,27 +70,26 @@
 	movzbl	(%rsi,%rax), %eax
 	movb	%al, (%rsi,%rcx)
 
-	movq %cr3, %rax;  # flush TLB 
-	movq %rax, %cr3;              
+	movq	%cr3, %rax;  # flush TLB 
+	movq	%rax, %cr3;              
 
-	movq	loop2(%rip), %rax
+	movq	%r11, %rax
 	incq	%rax
 	cmpq	$4095, %rax
 	movq	%rax, %rsi
-	movq	%rax, loop2(%rip)
-	jbe	.L111
-	movq	loop(%rip), %rax
+	movq	%rax, %r11
+	jbe	copy_one_page
+	movq	%r10, %rax
 	incq	%rax
 	movq	%rax, %rcx
-	movq	%rax, loop(%rip)
+	movq	%rax, %r10
 	mov	nr_copy_pages(%rip), %eax
 	cmpq	%rax, %rcx
 	jb	.L105
-.L108:
-	.align 4
+done:
 	movl	$24, %eax
-
-	movl %eax, %ds
+	movl	%eax, %ds
+	
 	movq saved_context_esp(%rip), %rsp
 	movq saved_context_ebp(%rip), %rbp
 	movq saved_context_eax(%rip), %rax
@@ -111,11 +109,3 @@
 	pushq saved_context_eflags(%rip) ; popfq
 	call	swsusp_restore
 	ret
-
-	.section .data.nosave, "aw"
-	.align 8
-loop:
-	.quad 0
-loop2:	
-	.quad 0		
-	.previous


-- 
People were complaining that M$ turns users into beta-testers...
...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl!