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Date: Thu, 07 Feb 2008 14:38:54 -0800
From: "H. Peter Anvin" <hpa@...or.com>
To: "Rafael J. Wysocki" <rjw@...k.pl>
CC: Pavel Machek <pavel@....cz>,
kernel list <linux-kernel@...r.kernel.org>,
Linux-pm mailing list <linux-pm@...ts.osdl.org>
Subject: Re: [rft] s2ram wakeup moves to .c, could fix few machines
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
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