swsusp: fix x86-64 - do not use memory in copy loop

From: Pavel Machek
Date: Sun Oct 03 2004 - 17:11:58 EST


Hi!

In assembly code, there are some problems with "nosave" section
(linker was doing something stupid, like duplicating the section). We
attempted to fix it, but fix was worse then first problem. This fixes
is for good: We no longer use any memory in the copy loop. (Plus it
fixes indentation and uses meaningfull labels.)

Patch is against 2.6.9-rc3. -mm has sligtly different version, with
more text on ".section .data.nosave" line. Those lines should really
be removed.
Pavel

--- clean/arch/x86_64/kernel/suspend_asm.S 2004-10-01 00:30:08.000000000 +0200
+++ linux/arch/x86_64/kernel/suspend_asm.S 2004-10-02 18:35:04.000000000 +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
@@ -111,10 +109,3 @@
pushq saved_context_eflags(%rip) ; popfq
call swsusp_restore
ret
-
- .section .data.nosave
-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!
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