mirror of
https://github.com/torvalds/linux
synced 2024-09-26 22:38:50 +00:00
916f676f8d
UEFI stands for "Unified Extensible Firmware Interface", where "Firmware" is an ancient African word meaning "Why do something right when you can do it so wrong that children will weep and brave adults will cower before you", and "UEI" is Celtic for "We missed DOS so we burned it into your ROMs". The UEFI specification provides for runtime services (ie, another way for the operating system to be forced to depend on the firmware) and we rely on these for certain trivial tasks such as setting up the bootloader. But some hardware fails to work if we attempt to use these runtime services from physical mode, and so we have to switch into virtual mode. So far so dreadful. The specification makes it clear that the operating system is free to do whatever it wants with boot services code after ExitBootServices() has been called. SetVirtualAddressMap() can't be called until ExitBootServices() has been. So, obviously, a whole bunch of EFI implementations call into boot services code when we do that. Since we've been charmingly naive and trusted that the specification may be somehow relevant to the real world, we've already stuffed a picture of a penguin or something in that address space. And just to make things more entertaining, we've also marked it non-executable. This patch allocates the boot services regions during EFI init and makes sure that they're executable. Then, after SetVirtualAddressMap(), it discards them and everyone lives happily ever after. Except for the ones who have to work on EFI, who live sad lives haunted by the knowledge that someone's eventually going to write yet another firmware specification. [ hpa: adding this to urgent with a stable tag since it fixes currently-broken hardware. However, I do not know what the dependencies are and so I do not know which -stable versions this may be a candidate for. ] Signed-off-by: Matthew Garrett <mjg@redhat.com> Link: http://lkml.kernel.org/r/1306331593-28715-1-git-send-email-mjg@redhat.com Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@kernel.org>
100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
/*
|
|
* x86_64 specific EFI support functions
|
|
* Based on Extensible Firmware Interface Specification version 1.0
|
|
*
|
|
* Copyright (C) 2005-2008 Intel Co.
|
|
* Fenghua Yu <fenghua.yu@intel.com>
|
|
* Bibo Mao <bibo.mao@intel.com>
|
|
* Chandramouli Narayanan <mouli@linux.intel.com>
|
|
* Huang Ying <ying.huang@intel.com>
|
|
*
|
|
* Code to convert EFI to E820 map has been implemented in elilo bootloader
|
|
* based on a EFI patch by Edgar Hucek. Based on the E820 map, the page table
|
|
* is setup appropriately for EFI runtime code.
|
|
* - mouli 06/14/2007.
|
|
*
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/types.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/bootmem.h>
|
|
#include <linux/ioport.h>
|
|
#include <linux/module.h>
|
|
#include <linux/efi.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/io.h>
|
|
#include <linux/reboot.h>
|
|
|
|
#include <asm/setup.h>
|
|
#include <asm/page.h>
|
|
#include <asm/e820.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/tlbflush.h>
|
|
#include <asm/proto.h>
|
|
#include <asm/efi.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/fixmap.h>
|
|
|
|
static pgd_t save_pgd __initdata;
|
|
static unsigned long efi_flags __initdata;
|
|
|
|
static void __init early_code_mapping_set_exec(int executable)
|
|
{
|
|
efi_memory_desc_t *md;
|
|
void *p;
|
|
|
|
if (!(__supported_pte_mask & _PAGE_NX))
|
|
return;
|
|
|
|
/* Make EFI service code area executable */
|
|
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
|
|
md = p;
|
|
if (md->type == EFI_RUNTIME_SERVICES_CODE ||
|
|
md->type == EFI_BOOT_SERVICES_CODE)
|
|
efi_set_executable(md, executable);
|
|
}
|
|
}
|
|
|
|
void __init efi_call_phys_prelog(void)
|
|
{
|
|
unsigned long vaddress;
|
|
|
|
early_code_mapping_set_exec(1);
|
|
local_irq_save(efi_flags);
|
|
vaddress = (unsigned long)__va(0x0UL);
|
|
save_pgd = *pgd_offset_k(0x0UL);
|
|
set_pgd(pgd_offset_k(0x0UL), *pgd_offset_k(vaddress));
|
|
__flush_tlb_all();
|
|
}
|
|
|
|
void __init efi_call_phys_epilog(void)
|
|
{
|
|
/*
|
|
* After the lock is released, the original page table is restored.
|
|
*/
|
|
set_pgd(pgd_offset_k(0x0UL), save_pgd);
|
|
__flush_tlb_all();
|
|
local_irq_restore(efi_flags);
|
|
early_code_mapping_set_exec(0);
|
|
}
|
|
|
|
void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size,
|
|
u32 type)
|
|
{
|
|
unsigned long last_map_pfn;
|
|
|
|
if (type == EFI_MEMORY_MAPPED_IO)
|
|
return ioremap(phys_addr, size);
|
|
|
|
last_map_pfn = init_memory_mapping(phys_addr, phys_addr + size);
|
|
if ((last_map_pfn << PAGE_SHIFT) < phys_addr + size) {
|
|
unsigned long top = last_map_pfn << PAGE_SHIFT;
|
|
efi_ioremap(top, size - (top - phys_addr), type);
|
|
}
|
|
|
|
return (void __iomem *)__va(phys_addr);
|
|
}
|