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efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint

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Expose efi_entry() as the PE/COFF entrypoint directly, instead of
jumping into a wrapper that fiddles with stack buffers and other
stuff that the compiler is much better at. The only reason this
code exists is to obtain a pointer to the base of the image, but
we can get the same value from the loaded_image protocol, which
we already need for other reasons anyway.

Update the return type as well, to make it consistent with what
is required for a PE/COFF executable entrypoint.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-02-17 12:44:37 +01:00
parent e951a1f427
commit 9f9223778e
8 changed files with 58 additions and 126 deletions
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2
arch/arm/boot/compressed/efi-header.S
View file

@ -60,7 +60,7 @@ optional_header:
.long __pecoff_code_size @ SizeOfCode
.long __pecoff_data_size @ SizeOfInitializedData
.long 0 @ SizeOfUninitializedData
.long efi_stub_entry - start @ AddressOfEntryPoint
.long efi_entry - start @ AddressOfEntryPoint
.long start_offset @ BaseOfCode
.long __pecoff_data_start - start @ BaseOfData

40
arch/arm/boot/compressed/head.S
View file

@ -1437,33 +1437,15 @@ __enter_kernel:
reloc_code_end:
#ifdef CONFIG_EFI_STUB
.align 2
_start: .long start - .
ENTRY(efi_enter_kernel)
mov r7, r0 @ preserve image base
mov r4, r1 @ preserve DT pointer
ENTRY(efi_stub_entry)
@ allocate space on stack for passing current zImage address
@ and for the EFI stub to return of new entry point of
@ zImage, as EFI stub may copy the kernel. Pointer address
@ is passed in r2. r0 and r1 are passed through from the
@ EFI firmware to efi_entry
adr ip, _start
ldr r3, [ip]
add r3, r3, ip
stmfd sp!, {r3, lr}
mov r2, sp @ pass zImage address in r2
bl efi_entry
@ Check for error return from EFI stub. r0 has FDT address
@ or error code.
cmn r0, #1
beq efi_load_fail
@ Preserve return value of efi_entry() in r4
mov r4, r0
add r1, r4, #SZ_2M @ DT end
mov r0, r4 @ DT start
add r1, r4, r2 @ DT end
bl cache_clean_flush
ldr r0, [sp] @ relocated zImage
mov r0, r7 @ relocated zImage
ldr r1, =_edata @ size of zImage
add r1, r1, r0 @ end of zImage
bl cache_clean_flush
@ -1473,9 +1455,8 @@ ENTRY(efi_stub_entry)
@ inside the PE/COFF loader allocated region is unsafe. Let's
@ assume our own zImage relocation code did a better job, and
@ jump into its version of this routine before proceeding.
ldr r0, [sp] @ relocated zImage
ldr r1, .Ljmp
sub r1, r0, r1
sub r1, r7, r1
mov pc, r1 @ no mode switch
0:
bl cache_off
@ -1487,12 +1468,7 @@ ENTRY(efi_stub_entry)
mov r1, #0xFFFFFFFF
mov r2, r4
b __efi_start
efi_load_fail:
@ Return EFI_LOAD_ERROR to EFI firmware on error.
ldr r0, =0x80000001
ldmfd sp!, {ip, pc}
ENDPROC(efi_stub_entry)
ENDPROC(efi_enter_kernel)
.align 2
.Ljmp: .long start - 0b
#endif

86
arch/arm64/kernel/efi-entry.S
View file

@ -10,81 +10,35 @@
#include <asm/assembler.h>
#define EFI_LOAD_ERROR 0x8000000000000001
__INIT
/*
* We arrive here from the EFI boot manager with:
*
* * CPU in little-endian mode
* * MMU on with identity-mapped RAM
* * Icache and Dcache on
*
* We will most likely be running from some place other than where
* we want to be. The kernel image wants to be placed at TEXT_OFFSET
* from start of RAM.
*/
ENTRY(entry)
/*
* Create a stack frame to save FP/LR with extra space
* for image_addr variable passed to efi_entry().
*/
stp x29, x30, [sp, #-32]!
mov x29, sp
/*
* Call efi_entry to do the real work.
* x0 and x1 are already set up by firmware. Current runtime
* address of image is calculated and passed via *image_addr.
*
* unsigned long efi_entry(void *handle,
* efi_system_table_t *sys_table,
* unsigned long *image_addr) ;
*/
adr_l x8, _text
add x2, sp, 16
str x8, [x2]
bl efi_entry
cmn x0, #1
b.eq efi_load_fail
ENTRY(efi_enter_kernel)
/*
* efi_entry() will have copied the kernel image if necessary and we
* return here with device tree address in x0 and the kernel entry
* point stored at *image_addr. Save those values in registers which
* are callee preserved.
* end up here with device tree address in x1 and the kernel entry
* point stored in x0. Save those values in registers which are
* callee preserved.
*/
mov x20, x0 // DTB address
ldr x0, [sp, #16] // relocated _text address
ldr w21, =stext_offset
add x21, x0, x21
/*
* Calculate size of the kernel Image (same for original and copy).
*/
adr_l x1, _text
adr_l x2, _edata
sub x1, x2, x1
mov x19, x0 // relocated Image address
mov x20, x1 // DTB address
/*
* Flush the copied Image to the PoC, and ensure it is not shadowed by
* stale icache entries from before relocation.
*/
ldr w1, =kernel_size
bl __flush_dcache_area
ic ialluis
dsb sy
/*
* Ensure that the rest of this function (in the original Image) is
* visible when the caches are disabled. The I-cache can't have stale
* entries for the VA range of the current image, so no maintenance is
* necessary.
* Jump across, into the copy of the image that we just cleaned
* to the PoC, so that we can safely disable the MMU and caches.
*/
adr x0, entry
adr x1, entry_end
sub x1, x1, x0
bl __flush_dcache_area
ldr w0, .Ljmp
sub x0, x19, w0, sxtw
br x0
0:
/* Turn off Dcache and MMU */
mrs x0, CurrentEL
cmp x0, #CurrentEL_EL2
@ -109,12 +63,6 @@ ENTRY(entry)
mov x1, xzr
mov x2, xzr
mov x3, xzr
br x21
efi_load_fail:
mov x0, #EFI_LOAD_ERROR
ldp x29, x30, [sp], #32
ret
entry_end:
ENDPROC(entry)
b stext
ENDPROC(efi_enter_kernel)
.Ljmp: .long _text - 0b

2
arch/arm64/kernel/efi-header.S
View file

@ -27,7 +27,7 @@ optional_header:
.long __initdata_begin - efi_header_end // SizeOfCode
.long __pecoff_data_size // SizeOfInitializedData
.long 0 // SizeOfUninitializedData
.long __efistub_entry - _head // AddressOfEntryPoint
.long __efistub_efi_entry - _head // AddressOfEntryPoint
.long efi_header_end - _head // BaseOfCode
extra_header_fields:

4
arch/arm64/kernel/image-vars.h
View file

@ -12,7 +12,8 @@
#ifdef CONFIG_EFI
__efistub_stext_offset = stext - _text;
__efistub_kernel_size = _edata - _text;
/*
* The EFI stub has its own symbol namespace prefixed by __efistub_, to
@ -42,6 +43,7 @@ __efistub___memset = __pi_memset;
#endif
__efistub__text = _text;
__efistub_stext = stext;
__efistub__end = _end;
__efistub__edata = _edata;
__efistub_screen_info = screen_info;

46
drivers/firmware/efi/libstub/arm-stub.c
View file

@ -10,6 +10,7 @@
*/
#include <linux/efi.h>
#include <linux/libfdt.h>
#include <linux/sort.h>
#include <asm/efi.h>
@ -100,17 +101,22 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
unsigned long *reserve_size,
unsigned long dram_base,
efi_loaded_image_t *image);
asmlinkage void __noreturn efi_enter_kernel(unsigned long entrypoint,
unsigned long fdt_addr,
unsigned long fdt_size);
/*
* EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
* that is described in the PE/COFF header. Most of the code is the same
* for both archictectures, with the arch-specific code provided in the
* handle_kernel_image() function.
*/
unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
unsigned long *image_addr)
efi_status_t efi_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg)
{
efi_loaded_image_t *image;
efi_status_t status;
unsigned long image_addr;
unsigned long image_size = 0;
unsigned long dram_base;
/* addr/point and size pairs for memory management*/
@ -120,7 +126,6 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
unsigned long fdt_size = 0;
char *cmdline_ptr = NULL;
int cmdline_size = 0;
unsigned long new_fdt_addr;
efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
unsigned long reserve_addr = 0;
unsigned long reserve_size = 0;
@ -130,8 +135,10 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
sys_table = sys_table_arg;
/* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
status = EFI_INVALID_PARAMETER;
goto fail;
}
status = check_platform_features();
if (status != EFI_SUCCESS)
@ -152,6 +159,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
dram_base = get_dram_base();
if (dram_base == EFI_ERROR) {
pr_efi_err("Failed to find DRAM base\n");
status = EFI_LOAD_ERROR;
goto fail;
}
@ -163,6 +171,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
if (!cmdline_ptr) {
pr_efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
status = EFI_OUT_OF_RESOURCES;
goto fail;
}
@ -178,7 +187,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
si = setup_graphics();
status = handle_kernel_image(image_addr, &image_size,
status = handle_kernel_image(&image_addr, &image_size,
&reserve_addr,
&reserve_size,
dram_base, image);
@ -227,7 +236,7 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
status = handle_cmdline_files(image, cmdline_ptr, "initrd=",
efi_get_max_initrd_addr(dram_base,
*image_addr),
image_addr),
(unsigned long *)&initrd_addr,
(unsigned long *)&initrd_size);
if (status != EFI_SUCCESS)
@ -257,33 +266,30 @@ unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
install_memreserve_table();
new_fdt_addr = fdt_addr;
status = allocate_new_fdt_and_exit_boot(handle,
&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
initrd_addr, initrd_size, cmdline_ptr,
fdt_addr, fdt_size);
status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
efi_get_max_fdt_addr(dram_base),
initrd_addr, initrd_size,
cmdline_ptr, fdt_addr, fdt_size);
if (status != EFI_SUCCESS)
goto fail_free_initrd;
/*
* If all went well, we need to return the FDT address to the
* calling function so it can be passed to kernel as part of
* the kernel boot protocol.
*/
if (status == EFI_SUCCESS)
return new_fdt_addr;
efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
/* not reached */
fail_free_initrd:
pr_efi_err("Failed to update FDT and exit boot services\n");
efi_free(initrd_size, initrd_addr);
efi_free(fdt_size, fdt_addr);
fail_free_image:
efi_free(image_size, *image_addr);
efi_free(image_size, image_addr);
efi_free(reserve_size, reserve_addr);
fail_free_cmdline:
free_screen_info(si);
efi_free(cmdline_size, (unsigned long)cmdline_ptr);
fail:
return EFI_ERROR;
return status;
}
static int cmp_mem_desc(const void *l, const void *r)

1
drivers/firmware/efi/libstub/arm32-stub.c
View file

@ -227,6 +227,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
* Relocate the zImage, so that it appears in the lowest 128 MB
* memory window.
*/
*image_addr = (unsigned long)image->image_base;
*image_size = image->image_size;
status = efi_relocate_kernel(image_addr, *image_size, *image_size,
kernel_base + MAX_UNCOMP_KERNEL_SIZE, 0, 0);

3
drivers/firmware/efi/libstub/arm64-stub.c
View file

@ -49,7 +49,6 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
{
efi_status_t status;
unsigned long kernel_size, kernel_memsize = 0;
void *old_image_addr = (void *)*image_addr;
unsigned long preferred_offset;
u64 phys_seed = 0;
@ -147,7 +146,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
}
*image_addr = *reserve_addr + TEXT_OFFSET;
}
memcpy((void *)*image_addr, old_image_addr, kernel_size);
memcpy((void *)*image_addr, image->image_base, kernel_size);
return EFI_SUCCESS;
}