patch-2.4.22 linux-2.4.22/include/asm-i386/save_state.h

• Lines: 213
• Date: 2003-08-25 04:44:43.000000000 -0700
• Orig file: linux-2.4.21/include/asm-i386/save_state.h
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.21/include/asm-i386/save_state.h linux-2.4.22/include/asm-i386/save_state.h
@@ -0,0 +1,212 @@
+#ifndef __ASM_I386_SAVE_STATE_H
+#define __ASM_I386_SAVE_STATE_H
+
+/*
+ * Copyright 2001-2002 Pavel Machek <pavel@suse.cz>
+ * Based on code
+ * Copyright 2001 Patrick Mochel <mochel@osdl.org>
+ */
+#include <asm/desc.h>
+#include <asm/i387.h>
+
+/* image of the saved processor state */
+struct saved_context {
+	u32 eax, ebx, ecx, edx;
+	u32 esp, ebp, esi, edi;
+	u16 es, fs, gs, ss;
+	u32 cr0, cr2, cr3, cr4;
+	u16 gdt_pad;
+	u16 gdt_limit;
+	u32 gdt_base;
+	u16 idt_pad;
+	u16 idt_limit;
+	u32 idt_base;
+	u16 ldt;
+	u16 tss;
+	u32 tr;
+	u32 safety;
+	u32 return_address;
+	u32 eflags;
+} __attribute__((packed));
+
+static struct saved_context saved_context;
+
+#define loaddebug(thread,register) \
+               __asm__("movl %0,%%db" #register  \
+                       : /* no output */ \
+                       :"r" ((thread)->debugreg[register]))
+
+
+/*
+ * 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)
+{
+	kernel_fpu_begin();
+
+	/*
+	 * descriptor tables
+	 */
+	asm volatile ("sgdt (%0)" : "=m" (saved_context.gdt_limit));
+	asm volatile ("sidt (%0)" : "=m" (saved_context.idt_limit));
+	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));
+
+	/*
+	 * segment registers
+	 */
+	asm volatile ("movw %%es, %0" : "=r" (saved_context.es));
+	asm volatile ("movw %%fs, %0" : "=r" (saved_context.fs));
+	asm volatile ("movw %%gs, %0" : "=r" (saved_context.gs));
+	asm volatile ("movw %%ss, %0" : "=r" (saved_context.ss));
+
+	/*
+	 * control registers 
+	 */
+	asm volatile ("movl %%cr0, %0" : "=r" (saved_context.cr0));
+	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 fix_processor_context(void)
+{
+	int nr = smp_processor_id();
+	struct tss_struct * t = &init_tss[nr];
+
+	set_tss_desc(nr,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. */
+        gdt_table[__TSS(nr)].b &= 0xfffffdff;
+
+	load_TR(nr);		/* This does ltr */
+	__load_LDT(nr);		/* This does lldt */
+
+	/*
+	 * Now maybe reload the debug registers
+	 */
+	if (current->thread.debugreg[7]){
+                loaddebug(&current->thread, 0);
+                loaddebug(&current->thread, 1);
+                loaddebug(&current->thread, 2);
+                loaddebug(&current->thread, 3);
+                /* no 4 and 5 */
+                loaddebug(&current->thread, 6);
+                loaddebug(&current->thread, 7);
+	}
+
+}
+
+static void
+do_fpu_end(void)
+{
+        /* restore FPU regs if necessary */
+	/* Do it out of line so that gcc does not move cr0 load to some stupid place */
+        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)
+{
+	/*
+	 * first restore %ds, so we can access our data properly
+	 */
+	asm volatile (".align 4");
+	asm volatile ("movw %0, %%ds" :: "r" ((u16)__KERNEL_DS));
+
+
+	/*
+	 * control registers
+	 */
+	asm volatile ("movl %0, %%cr4" :: "r" (saved_context.cr4));
+	asm volatile ("movl %0, %%cr3" :: "r" (saved_context.cr3));
+	asm volatile ("movl %0, %%cr2" :: "r" (saved_context.cr2));
+	asm volatile ("movl %0, %%cr0" :: "r" (saved_context.cr0));
+	
+	/*
+	 * segment registers
+	 */
+	asm volatile ("movw %0, %%es" :: "r" (saved_context.es));
+	asm volatile ("movw %0, %%fs" :: "r" (saved_context.fs));
+	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
+	 */
+	asm volatile ("lgdt (%0)" :: "m" (saved_context.gdt_limit));
+	asm volatile ("lidt (%0)" :: "m" (saved_context.idt_limit));
+	asm volatile ("lldt (%0)" :: "m" (saved_context.ldt));
+
+	fix_processor_context();
+	do_fpu_end();
+}
+
+#endif 
+