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Subjectswsusp: rewrite critical parts to assembly
Hi!

This rewrites parts that can not be safely written in C to
assembly. This time with S3 code, too, so you no longer see moves to
%esp in C code. Please apply,
Pavel

--- clean/arch/i386/kernel/Makefile 2002-10-20 16:22:31.000000000 +0200
+++ linux-swsusp/arch/i386/kernel/Makefile 2002-11-07 18:26:45.000000000 +0100
@@ -25,7 +25,7 @@
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
--- clean/arch/i386/kernel/acpi_wakeup.S 2002-06-03 11:43:27.000000000 +0200
+++ linux-swsusp/arch/i386/kernel/acpi_wakeup.S 2002-11-12 18:27:42.000000000 +0100
@@ -262,6 +267,48 @@

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
--- clean/arch/i386/kernel/suspend.c 2002-11-01 00:37:05.000000000 +0100
+++ linux-swsusp/arch/i386/kernel/suspend.c 2002-11-12 18:12:40.000000000 +0100
@@ -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();

@@ -60,23 +45,6 @@
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
*/
asm volatile ("movw %%es, %0" : "=m" (saved_context.es));
@@ -91,11 +59,6 @@
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 @@
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
@@ -144,24 +89,6 @@
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 @@
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 @@

}

-
#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;
- }
+int loop __nosavedata = 0;
+int loop2 __nosavedata = 0;

- /* We want to run from swapper_pg_dir, since swapper_pg_dir is stored in constant
- * place in memory
- */
-
- __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
--- clean/arch/i386/kernel/suspend_asm.S 2002-11-07 18:26:08.000000000 +0100
+++ linux-swsusp/arch/i386/kernel/suspend_asm.S 2002-11-12 18:24:13.000000000 +0100
@@ -0,0 +1,80 @@
+.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

--- clean/include/asm-i386/suspend.h 2002-11-01 00:37:39.000000000 +0100
+++ linux-swsusp/include/asm-i386/suspend.h 2002-11-07 17:57:46.000000000 +0100
@@ -15,8 +15,6 @@

/* 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 @@
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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