Re: [rft] s2ram wakeup moves to .c, could fix few machines

From: H. Peter Anvin
Date: Thu Feb 07 2008 - 17:39:22 EST

Rafael J. Wysocki wrote:
Index: linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.S
===================================================================
--- /dev/null
+++ linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.S
@@ -0,0 +1,122 @@
+/*
+ * ACPI wakeup real mode startup stub
+ */
+#include <asm/segment.h>
+#include <asm/msr-index.h>
+#include <asm/page_64.h>
+#include <asm/pgtable_64.h>
+
+ .code16
+ .section ".header", "a"
+
+/* This should match the structure in wakeup.h */
+ .globl wakeup_header
+wakeup_header:
+video_mode: .short 0 /* Video mode number */
+pmode_return: .byte 0x66, 0xea /* ljmpl */
+ .long 0 /* offset goes here */
+ .short __KERNEL_CS

Missing a .short pad here... Pavel fixed that at some point, I thought.

+pmode_cr0: .long 0 /* Saved %cr0 */
+pmode_cr3: .long 0 /* Saved %cr3 */
+pmode_cr4: .long 0 /* Saved %cr4 */
+pmode_efer: .quad 0 /* Saved EFER */
+pmode_gdt: .quad 0
+realmode_flags: .long 0
+real_magic: .long 0
+trampoline_segment: .word 0
+signature: .long 0x51ee1111
+
+ .text
+ .globl _start
+ .code16
+wakeup_code:
+_start:
+ cli
+ cld
+
+ /* Set up segments */
+ movw %cs, %ax
+ movw %ax, %ds
+ movw %ax, %es
+ movw %ax, %ss
+
+ movl $wakeup_stack_end, %esp
+
+ /* Clear the EFLAGS */
+ pushl $0
+ popfl
+
+ /* Check header signature... */
+ movl signature, %eax
+ cmpl $0x51ee1111, %eax
+ jne bogus_real_magic
+
+ /* Check we really have everything... */
+ movl end_signature, %eax
+ cmpl $0x65a22c82, %eax
+ jne bogus_real_magic
+
+ /* Zero the bss */
+ xorl %eax, %eax
+ movw $__bss_start, %di
+ movw $__bss_end + 3, %cx
+ subw %di, %cx
+ shrw $2, %cx
+ rep
+ stosl
+
+ /* Call the C code */
+ calll main
+
+ /* Do any other stuff... */
+
+#ifndef CONFIG_64BIT
+ /* This could also be done in C code... */
+ movl pmode_cr3, %eax
+ movl %eax, %cr3
+
+ movl pmode_cr4, %ecx
+ jecxz 1f
+ movl %ecx, %cr4
+1:
+ movl pmode_efer, %eax
+ movl pmode_efer + 4, %edx
+ movl %eax, %ecx
+ orl %edx, %ecx
+ jz 1f
+ movl $0xc0000080, %ecx
+ wrmsr
+1:
+
+ lgdtl pmode_gdt
+
+ /* This really couldn't... */
+ movl pmode_cr0, %eax
+ movl %eax, %cr0
+ jmp pmode_return
+#else
+ pushw $0
+ pushw trampoline_segment
+ pushw $0
+ lret
+#endif
+
+bogus_real_magic:
+1:
+ hlt
+ jmp 1b
+
+ .data
+ .balign 4
+ .globl HEAP, heap_end
+HEAP:
+ .long wakeup_heap
+heap_end:
+ .long wakeup_stack
+
+ .bss
+wakeup_heap:
+ .space 2048
+wakeup_stack:
+ .space 2048
+wakeup_stack_end:
Index: linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.h
===================================================================
--- /dev/null
+++ linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.h
@@ -0,0 +1,29 @@
+/*
+ * Definitions for the wakeup data structure at the head of the
+ * wakeup code.
+ */
+
+#ifndef ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H
+#define ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H
+
+#include <linux/types.h>
+
+/* This must match data at wakeup.S */
+struct wakeup_header {
+ u16 video_mode; /* Video mode number */
+ u16 _jmp1; /* ljmpl opcode, 32-bit only */
+ u32 pmode_entry; /* Protected mode resume point, 32-bit only */
+ u16 _jmp2; /* CS value, 32-bit only */
+ u32 pmode_cr0; /* Protected mode cr0 */
+ u32 pmode_cr3; /* Protected mode cr3 */
+ u32 pmode_cr4; /* Protected mode cr4 */
+ u32 pmode_efer_low; /* Protected mode EFER */
+ u32 pmode_efer_high;
+ u64 pmode_gdt;
+ u32 realmode_flags;
+ u32 real_magic;
+ u16 trampoline_segment; /* segment with trampoline code, 64-bit only */
+ u32 signature; /* To check we have correct structure */
+} __attribute__((__packed__));
+
+#endif /* ARCH_X86_KERNEL_ACPI_RM_WAKEUP_H */
Index: linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.ld
===================================================================
--- /dev/null
+++ linux-2.6/arch/x86/kernel/acpi/realmode/wakeup.ld
@@ -0,0 +1,51 @@
+/*
+ * wakeup.ld
+ *
+ * Linker script for the real-mode wakeup code
+ */
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(_start)
+
+SECTIONS
+{
+ . = 0x3f00;
+ .header : { *(.header) }
+
+ . = 0;
+ .text : { *(.text*) }
+
+ . = ALIGN(16);
+ .rodata : { *(.rodata*) }
+
+ .videocards : {
+ video_cards = .;
+ *(.videocards)
+ video_cards_end = .;
+ }
+
+ . = ALIGN(16);
+ .data : { *(.data*) }
+
+ .signature : {
+ end_signature = .;
+ LONG(0x65a22c82)
+ }
+
+ . = ALIGN(16);
+ .bss :
+ {
+ __bss_start = .;
+ *(.bss)
+ __bss_end = .;
+ }
+
+ . = ALIGN(16);
+ _end = .;
+
+ /DISCARD/ : { *(.note*) }
+
+ /* Adjust this as appropriate */
+ /* This allows 4 pages (16K) */
+ . = ASSERT(_end <= 0x4000, "Wakeup too big!");
+}
Index: linux-2.6/arch/x86/kernel/acpi/sleep.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/acpi/sleep.c
+++ linux-2.6/arch/x86/kernel/acpi/sleep.c
@@ -11,29 +11,84 @@
#include <linux/cpumask.h>
#include <asm/smp.h>
+#include "realmode/wakeup.h"
/* address in low memory of the wakeup routine. */
-unsigned long acpi_wakeup_address = 0;
+static unsigned long acpi_realmode;
+unsigned long acpi_wakeup_address;
unsigned long acpi_realmode_flags;
-extern char wakeup_start, wakeup_end;
+extern char wakeup_code_start, wakeup_code_end;
extern unsigned long acpi_copy_wakeup_routine(unsigned long);
+extern unsigned long setup_trampoline(void);
+extern void wakeup_long64(void);
+
+extern unsigned long saved_video_mode;
+extern long saved_magic;
+extern volatile unsigned long init_rsp;
+extern void (*initial_code)(void);
+#ifndef CONFIG_64BIT
+extern int wakeup_pmode_return;
+extern char swsusp_pg_dir[PAGE_SIZE];
+#else
+static char temp_stack[10240];
+#endif
+
+extern unsigned long FASTCALL(acpi_copy_wakeup_routine(unsigned long));
/**
* acpi_save_state_mem - save kernel state
*
* Create an identity mapped page table and copy the wakeup routine to
* low memory.
+ *
+ * Note that this is too late to change acpi_wakeup_address.
*/
int acpi_save_state_mem(void)
{
- if (!acpi_wakeup_address) {
- printk(KERN_ERR "Could not allocate memory during boot, S3 disabled\n");
+ struct wakeup_header *header;
+
+ if (!acpi_realmode) {
+ printk(KERN_ERR "Could not allocate memory during boot, "
+ "S3 disabled\n");
return -ENOMEM;
}
- memcpy((void *)acpi_wakeup_address, &wakeup_start,
- &wakeup_end - &wakeup_start);
- acpi_copy_wakeup_routine(acpi_wakeup_address);
+ memcpy((void *)acpi_realmode, &wakeup_code_start, 4*PAGE_SIZE);

Using a PAGE_SIZE multiplier here isn't a good thing...

+ header = (struct wakeup_header *)(acpi_realmode + 0x3f00);

... especially not with magic constants like this.

If you're putting the "header" at the end, then you should also replace the end_signature stuff since that's, then, redundant. Furthermore, by doing so, you're also padding the binary out to its maximum length, so you might as well just remove the .bss-clearing stuff.

It's not really clear to me why to do this what way...

+ if (header->signature != 0x51ee1111) {
+ printk(KERN_ERR "wakeup header does not match\n");
+ return -EINVAL;
+ }
+
+ header->video_mode = saved_video_mode;
+
+#ifndef CONFIG_64BIT
+ store_gdt(&header->pmode_gdt);
+
+ header->pmode_efer_low = nx_enabled;
+ if (header->pmode_efer_low & 1) {
+ /* This is strange, why not save efer, always? */
+ rdmsr(MSR_EFER, header->pmode_efer_low,
+ header->pmode_efer_high);
+ }

Yes, why not save EFER every time?

-hpa
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/