Commit 9ce91f36 authored by Pavel Machek's avatar Pavel Machek Committed by Linus Torvalds

[PATCH] swsusp: rewrite critical parts to assembly

This rewrites the parts that can not be safely written in C (ie the
low-level register save/restore) to assembly.
parent 6a56b85f
......@@ -24,7 +24,7 @@ obj-$(CONFIG_X86_SMP) += smp.o smpboot.o trampoline.o
obj-$(CONFIG_X86_MPPARSE) += mpparse.o
obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o
obj-$(CONFIG_X86_IO_APIC) += io_apic.o
obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o
obj-$(CONFIG_SOFTWARE_SUSPEND) += suspend.o suspend_asm.o
obj-$(CONFIG_X86_NUMAQ) += numaq.o
obj-$(CONFIG_PROFILING) += profile.o
obj-$(CONFIG_EDD) += edd.o
......
......@@ -262,6 +262,48 @@ ENTRY(saved_esp) .long 0
ENTRY(saved_magic) .long 0
ENTRY(do_suspend_lowlevel)
cmpl $0,4(%esp)
jne .L1432
call save_processor_state
movl %esp, saved_context_esp
movl %eax, saved_context_eax
movl %ebx, saved_context_ebx
movl %ecx, saved_context_ecx
movl %edx, saved_context_edx
movl %ebp, saved_context_ebp
movl %esi, saved_context_esi
movl %edi, saved_context_edi
pushfl ; popl saved_context_eflags
movl $.L1432,saved_eip
movl %esp,saved_esp
movl %ebp,saved_ebp
movl %ebx,saved_ebx
movl %edi,saved_edi
movl %esi,saved_esi
pushl $3
call acpi_enter_sleep_state
addl $4,%esp
ret
.p2align 4,,7
.L1432:
movl $104,%eax
movw %eax, %ds
movl saved_context_esp, %esp
movl saved_context_ebp, %ebp
movl saved_context_eax, %eax
movl saved_context_ebx, %ebx
movl saved_context_ecx, %ecx
movl saved_context_edx, %edx
movl saved_context_esi, %esi
movl saved_context_edi, %edi
call restore_processor_state
pushl saved_context_eflags ; popfl
ret
ALIGN
# saved registers
saved_gdt: .long 0,0
......
......@@ -28,26 +28,11 @@
#include <asm/tlbflush.h>
static struct saved_context saved_context;
unsigned long saved_context_eax, saved_context_ebx, saved_context_ecx, saved_context_edx;
unsigned long saved_context_esp, saved_context_ebp, saved_context_esi, saved_context_edi;
unsigned long saved_context_eflags;
/*
* save_processor_context
*
* Save the state of the processor before we go to sleep.
*
* return_stack is the value of the stack pointer (%esp) as the caller sees it.
* A good way could not be found to obtain it from here (don't want to make _too_
* many assumptions about the layout of the stack this far down.) Also, the
* handy little __builtin_frame_pointer(level) where level > 0, is blatantly
* buggy - it returns the value of the stack at the proper location, not the
* location, like it should (as of gcc 2.91.66)
*
* Note that the context and timing of this function is pretty critical.
* With a minimal amount of things going on in the caller and in here, gcc
* does a good job of being just a dumb compiler. Watch the assembly output
* if anything changes, though, and make sure everything is going in the right
* place.
*/
static inline void save_processor_context (void)
void save_processor_state(void)
{
kernel_fpu_begin();
......@@ -59,23 +44,6 @@ static inline void save_processor_context (void)
asm volatile ("sldt %0" : "=m" (saved_context.ldt));
asm volatile ("str %0" : "=m" (saved_context.tr));
/*
* save the general registers.
* note that gcc has constructs to specify output of certain registers,
* but they're not used here, because it assumes that you want to modify
* those registers, so it tries to be smart and save them beforehand.
* It's really not necessary, and kinda fishy (check the assembly output),
* so it's avoided.
*/
asm volatile ("movl %%esp, %0" : "=m" (saved_context.esp));
asm volatile ("movl %%eax, %0" : "=m" (saved_context.eax));
asm volatile ("movl %%ebx, %0" : "=m" (saved_context.ebx));
asm volatile ("movl %%ecx, %0" : "=m" (saved_context.ecx));
asm volatile ("movl %%edx, %0" : "=m" (saved_context.edx));
asm volatile ("movl %%ebp, %0" : "=m" (saved_context.ebp));
asm volatile ("movl %%esi, %0" : "=m" (saved_context.esi));
asm volatile ("movl %%edi, %0" : "=m" (saved_context.edi));
/* FIXME: Need to save XMM0..XMM15? */
/*
* segment registers
*/
......@@ -91,11 +59,6 @@ static inline void save_processor_context (void)
asm volatile ("movl %%cr2, %0" : "=r" (saved_context.cr2));
asm volatile ("movl %%cr3, %0" : "=r" (saved_context.cr3));
asm volatile ("movl %%cr4, %0" : "=r" (saved_context.cr4));
/*
* eflags
*/
asm volatile ("pushfl ; popl %0" : "=m" (saved_context.eflags));
}
static void
......@@ -106,26 +69,8 @@ do_fpu_end(void)
kernel_fpu_end();
}
/*
* restore_processor_context
*
* Restore the processor context as it was before we went to sleep
* - descriptor tables
* - control registers
* - segment registers
* - flags
*
* Note that it is critical that this function is declared inline.
* It was separated out from restore_state to make that function
* a little clearer, but it needs to be inlined because we won't have a
* stack when we get here (so we can't push a return address).
*/
static inline void restore_processor_context (void)
void restore_processor_state(void)
{
/*
* first restore %ds, so we can access our data properly
*/
asm volatile ("movw %0, %%ds" :: "r" (__KERNEL_DS));
/*
* control registers
......@@ -143,24 +88,6 @@ static inline void restore_processor_context (void)
asm volatile ("movw %0, %%gs" :: "r" (saved_context.gs));
asm volatile ("movw %0, %%ss" :: "r" (saved_context.ss));
/*
* the other general registers
*
* note that even though gcc has constructs to specify memory
* input into certain registers, it will try to be too smart
* and save them at the beginning of the function. This is esp.
* bad since we don't have a stack set up when we enter, and we
* want to preserve the values on exit. So, we set them manually.
*/
asm volatile ("movl %0, %%esp" :: "m" (saved_context.esp));
asm volatile ("movl %0, %%ebp" :: "m" (saved_context.ebp));
asm volatile ("movl %0, %%eax" :: "m" (saved_context.eax));
asm volatile ("movl %0, %%ebx" :: "m" (saved_context.ebx));
asm volatile ("movl %0, %%ecx" :: "m" (saved_context.ecx));
asm volatile ("movl %0, %%edx" :: "m" (saved_context.edx));
asm volatile ("movl %0, %%esi" :: "m" (saved_context.esi));
asm volatile ("movl %0, %%edi" :: "m" (saved_context.edi));
/*
* now restore the descriptor tables to their proper values
* ltr is done i fix_processor_context().
......@@ -170,42 +97,15 @@ static inline void restore_processor_context (void)
asm volatile ("lldt %0" :: "m" (saved_context.ldt));
fix_processor_context();
/*
* the flags
*/
asm volatile ("pushl %0 ; popfl" :: "m" (saved_context.eflags));
do_fpu_end();
}
#ifdef CONFIG_ACPI_SLEEP
void do_suspend_lowlevel(int resume)
{
/*
* FIXME: This function should really be written in assembly. Actually
* requirement is that it does not touch stack, because %esp will be
* wrong during resume before restore_processor_context(). Check
* assembly if you modify this.
*/
if (!resume) {
save_processor_context();
acpi_save_register_state((unsigned long)&&acpi_sleep_done);
acpi_enter_sleep_state(3);
return;
}
acpi_sleep_done:
acpi_restore_register_state();
restore_processor_context();
}
#endif
void fix_processor_context(void)
{
int cpu = smp_processor_id();
struct tss_struct * t = init_tss + cpu;
set_tss_desc(cpu,t); /* This just modifies memory; should not be neccessary. But... This is neccessary, because 386 hardware has concept of busy tsc or some similar stupidity. */
set_tss_desc(cpu,t); /* This just modifies memory; should not be neccessary. But... This is neccessary, because 386 hardware has concept of busy TSS or some similar stupidity. */
cpu_gdt_table[cpu][GDT_ENTRY_TSS].b &= 0xfffffdff;
load_TR_desc(); /* This does ltr */
......@@ -226,77 +126,9 @@ void fix_processor_context(void)
}
#ifdef CONFIG_SOFTWARE_SUSPEND
/* Local variables for do_magic */
static int loop __nosavedata = 0;
static int loop2 __nosavedata = 0;
/*
* (KG): Since we affect stack here, we make this function as flat and easy
* as possible in order to not provoke gcc to use local variables on the stack.
* Note that on resume, all (expect nosave) variables will have the state from
* the time of writing (suspend_save_image) and the registers (including the
* stack pointer, but excluding the instruction pointer) will be loaded with
* the values saved at save_processor_context() time.
*/
void do_magic(int resume)
{
/* DANGER WILL ROBINSON!
*
* If this function is too difficult for gcc to optimize, it will crash and burn!
* see above.
*
* DO NOT TOUCH.
*/
if (!resume) {
do_magic_suspend_1();
save_processor_context(); /* We need to capture registers and memory at "same time" */
do_magic_suspend_2(); /* If everything goes okay, this function does not return */
return;
}
/* We want to run from swapper_pg_dir, since swapper_pg_dir is stored in constant
* place in memory
*/
int loop __nosavedata = 0;
int loop2 __nosavedata = 0;
__asm__( "movl %%ecx,%%cr3\n" ::"c"(__pa(swapper_pg_dir)));
/*
* Final function for resuming: after copying the pages to their original
* position, it restores the register state.
*
* What about page tables? Writing data pages may toggle
* accessed/dirty bits in our page tables. That should be no problems
* with 4MB page tables. That's why we require have_pse.
*
* This loops destroys stack from under itself, so it better should
* not use any stack space, itself. When this function is entered at
* resume time, we move stack to _old_ place. This is means that this
* function must use no stack and no local variables in registers,
* until calling restore_processor_context();
*
* Critical section here: noone should touch saved memory after
* do_magic_resume_1; copying works, because nr_copy_pages,
* pagedir_nosave, loop and loop2 are nosavedata.
*/
do_magic_resume_1();
for (loop=0; loop < nr_copy_pages; loop++) {
/* You may not call something (like copy_page) here: see above */
for (loop2=0; loop2 < PAGE_SIZE; loop2++) {
*(((char *)((pagedir_nosave+loop)->orig_address))+loop2) =
*(((char *)((pagedir_nosave+loop)->address))+loop2);
__flush_tlb();
}
}
restore_processor_context();
/* Ahah, we now run with our old stack, and with registers copied from
suspend time */
do_magic_resume_2();
}
#endif
.text
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page.h>
ENTRY(do_magic):
pushl %ebx
cmpl $0,8(%esp)
jne .L1450
call do_magic_suspend_1
call save_processor_state
movl %esp, saved_context_esp
movl %eax, saved_context_eax
movl %ebx, saved_context_ebx
movl %ecx, saved_context_ecx
movl %edx, saved_context_edx
movl %ebp, saved_context_ebp
movl %esi, saved_context_esi
movl %edi, saved_context_edi
pushfl ; popl saved_context_eflags
call do_magic_suspend_2
jmp .L1449
.p2align 4,,7
.L1450:
movl $swapper_pg_dir-__PAGE_OFFSET,%ecx
movl %ecx,%cr3
call do_magic_resume_1
movl $0,loop
cmpl $0,nr_copy_pages
je .L1453
.p2align 4,,7
.L1455:
movl $0,loop2
.p2align 4,,7
.L1459:
movl pagedir_nosave,%ecx
movl loop,%eax
movl loop2,%edx
sall $4,%eax
movl 4(%ecx,%eax),%ebx
movl (%ecx,%eax),%eax
movb (%edx,%eax),%al
movb %al,(%edx,%ebx)
movl %cr3, %eax;
movl %eax, %cr3; # flush TLB
movl loop2,%eax
leal 1(%eax),%edx
movl %edx,loop2
movl %edx,%eax
cmpl $4095,%eax
jbe .L1459
movl loop,%eax
leal 1(%eax),%edx
movl %edx,loop
movl %edx,%eax
cmpl nr_copy_pages,%eax
jb .L1455
.p2align 4,,7
.L1453:
movl $104,%eax
movw %eax, %ds
movl saved_context_esp, %esp
movl saved_context_ebp, %ebp
movl saved_context_eax, %eax
movl saved_context_ebx, %ebx
movl saved_context_ecx, %ecx
movl saved_context_edx, %edx
movl saved_context_esi, %esi
movl saved_context_edi, %edi
call restore_processor_state
pushl saved_context_eflags ; popfl
call do_magic_resume_2
.L1449:
popl %ebx
ret
......@@ -15,8 +15,6 @@ arch_prepare_suspend(void)
/* image of the saved processor state */
struct saved_context {
unsigned long eax, ebx, ecx, edx;
unsigned long esp, ebp, esi, edi;
u16 es, fs, gs, ss;
unsigned long cr0, cr2, cr3, cr4;
u16 gdt_pad;
......@@ -30,9 +28,14 @@ struct saved_context {
unsigned long tr;
unsigned long safety;
unsigned long return_address;
unsigned long eflags;
} __attribute__((packed));
/* We'll access these from assembly, so we'd better have them outside struct */
extern unsigned long saved_context_eax, saved_context_ebx, saved_context_ecx, saved_context_edx;
extern unsigned long saved_context_esp, saved_context_ebp, saved_context_esi, saved_context_edi;
extern unsigned long saved_context_eflags;
#define loaddebug(thread,register) \
__asm__("movl %0,%%db" #register \
: /* no output */ \
......
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