Commit 24b5e20f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull EFI updates from Ingo Molnar:
 "The main changes are:

   - Use separate EFI page tables when executing EFI firmware code.
     This isolates the EFI context from the rest of the kernel, which
     has security and general robustness advantages.  (Matt Fleming)

   - Run regular UEFI firmware with interrupts enabled.  This is already
     the status quo under other OSs.  (Ard Biesheuvel)

   - Various x86 EFI enhancements, such as the use of non-executable
     attributes for EFI memory mappings.  (Sai Praneeth Prakhya)

   - Various arm64 UEFI enhancements.  (Ard Biesheuvel)

   - ... various fixes and cleanups.

  The separate EFI page tables feature got delayed twice already,
  because it's an intrusive change and we didn't feel confident about
  it - third time's the charm we hope!"

* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits)
  x86/mm/pat: Fix boot crash when 1GB pages are not supported by the CPU
  x86/efi: Only map kernel text for EFI mixed mode
  x86/efi: Map EFI_MEMORY_{XP,RO} memory region bits to EFI page tables
  x86/mm/pat: Don't implicitly allow _PAGE_RW in kernel_map_pages_in_pgd()
  efi/arm*: Perform hardware compatibility check
  efi/arm64: Check for h/w support before booting a >4 KB granular kernel
  efi/arm: Check for LPAE support before booting a LPAE kernel
  efi/arm-init: Use read-only early mappings
  efi/efistub: Prevent __init annotations from being used
  arm64/vmlinux.lds.S: Handle .init.rodata.xxx and .init.bss sections
  efi/arm64: Drop __init annotation from handle_kernel_image()
  x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings
  efi/runtime-wrappers: Run UEFI Runtime Services with interrupts enabled
  efi: Reformat GUID tables to follow the format in UEFI spec
  efi: Add Persistent Memory type name
  efi: Add NV memory attribute
  x86/efi: Show actual ending addresses in efi_print_memmap
  x86/efi/bgrt: Don't ignore the BGRT if the 'valid' bit is 0
  efivars: Use to_efivar_entry
  efi: Runtime-wrapper: Get rid of the rtc_lock spinlock
  ...
parents 26660a40 d367cef0

Documentation/efi-stub.txt

+2 −2
Original line number Diff line number Diff line
@@ -10,12 +10,12 @@ arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c, 
respectively. For ARM the EFI stub is implemented in

arch/arm/boot/compressed/efi-header.S and

arch/arm/boot/compressed/efi-stub.c. EFI stub code that is shared

between architectures is in drivers/firmware/efi/efi-stub-helper.c.

between architectures is in drivers/firmware/efi/libstub.



For arm64, there is no compressed kernel support, so the Image itself

masquerades as a PE/COFF image and the EFI stub is linked into the

kernel. The arm64 EFI stub lives in arch/arm64/kernel/efi-entry.S

and arch/arm64/kernel/efi-stub.c.

and drivers/firmware/efi/libstub/arm64-stub.c.



By using the EFI boot stub it's possible to boot a Linux kernel

without the use of a conventional EFI boot loader, such as grub or

Documentation/x86/x86_64/mm.txt

+6 −6
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ ffffec0000000000 - fffffc0000000000 (=44 bits) kasan shadow memory (16TB) 
... unused hole ...

ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks

... unused hole ...

ffffffef00000000 - ffffffff00000000 (=64 GB) EFI region mapping space

... unused hole ...

ffffffff80000000 - ffffffffa0000000 (=512 MB)  kernel text mapping, from phys 0

ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space

ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls
@@ -32,11 +34,9 @@ reference. 
Current X86-64 implementations only support 40 bits of address space,

but we support up to 46 bits. This expands into MBZ space in the page tables.



->trampoline_pgd:



We map EFI runtime services in the aforementioned PGD in the virtual

range of 64Gb (arbitrarily set, can be raised if needed)



0xffffffef00000000 - 0xffffffff00000000

We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual

memory window (this size is arbitrary, it can be raised later if needed).

The mappings are not part of any other kernel PGD and are only available

during EFI runtime calls.



-Andi Kleen, Jul 2004

arch/arm64/kernel/vmlinux.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -135,6 +135,7 @@ SECTIONS 
		CON_INITCALL

		SECURITY_INITCALL

		INIT_RAM_FS

		*(.init.rodata.* .init.bss)	/* from the EFI stub */

	}

	.exit.data : {

		ARM_EXIT_KEEP(EXIT_DATA)

arch/x86/include/asm/efi.h

+27 −1
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <asm/fpu/api.h>

#include <asm/pgtable.h>

#include <asm/tlb.h>



/*

 * We map the EFI regions needed for runtime services non-contiguously,
@@ -66,6 +67,17 @@ extern u64 asmlinkage efi_call(void *fp, ...); 


#define efi_call_phys(f, args...)		efi_call((f), args)



/*

 * Scratch space used for switching the pagetable in the EFI stub

 */

struct efi_scratch {

	u64	r15;

	u64	prev_cr3;

	pgd_t	*efi_pgt;

	bool	use_pgd;

	u64	phys_stack;

} __packed;



#define efi_call_virt(f, ...)						\

({									\

	efi_status_t __s;						\
@@ -73,7 +85,20 @@ extern u64 asmlinkage efi_call(void *fp, ...); 
	efi_sync_low_kernel_mappings();					\

	preempt_disable();						\

	__kernel_fpu_begin();						\

									\

	if (efi_scratch.use_pgd) {					\

		efi_scratch.prev_cr3 = read_cr3();			\

		write_cr3((unsigned long)efi_scratch.efi_pgt);		\

		__flush_tlb_all();					\

	}								\

									\

	__s = efi_call((void *)efi.systab->runtime->f, __VA_ARGS__);	\

									\

	if (efi_scratch.use_pgd) {					\

		write_cr3(efi_scratch.prev_cr3);			\

		__flush_tlb_all();					\

	}								\

									\

	__kernel_fpu_end();						\

	preempt_enable();						\

	__s;								\
@@ -113,11 +138,12 @@ extern void __init efi_memory_uc(u64 addr, unsigned long size); 
extern void __init efi_map_region(efi_memory_desc_t *md);

extern void __init efi_map_region_fixed(efi_memory_desc_t *md);

extern void efi_sync_low_kernel_mappings(void);

extern int __init efi_alloc_page_tables(void);

extern int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages);

extern void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages);

extern void __init old_map_region(efi_memory_desc_t *md);

extern void __init runtime_code_page_mkexec(void);

extern void __init efi_runtime_mkexec(void);

extern void __init efi_runtime_update_mappings(void);

extern void __init efi_dump_pagetable(void);

extern void __init efi_apply_memmap_quirks(void);

extern int __init efi_reuse_config(u64 tables, int nr_tables);

arch/x86/kernel/vmlinux.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -333,6 +333,7 @@ SECTIONS 
		__brk_limit = .;

	}



	. = ALIGN(PAGE_SIZE);

	_end = .;



        STABS_DEBUG

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