From: Ard Biesheuvel <ardb@kernel.org>
Date: Mon, 17 Feb 2020 12:44:37 +0100
Subject: efi/libstub/arm: Make efi_entry() an ordinary PE/COFF entrypoint
Patch-mainline: v5.7-rc1
Git-commit: 9f9223778ef385e79dc67f5ee48ee4c1fb757f6b
References: jsc#SLE-16407
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>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
arch/arm/boot/compressed/efi-header.S | 2
arch/arm/boot/compressed/head.S | 40 ++-----------
arch/arm64/kernel/efi-entry.S | 86 +++++-------------------------
arch/arm64/kernel/efi-header.S | 2
arch/arm64/kernel/image-vars.h | 4 +
drivers/firmware/efi/libstub/arm-stub.c | 46 +++++++++-------
drivers/firmware/efi/libstub/arm32-stub.c | 1
drivers/firmware/efi/libstub/arm64-stub.c | 3 -
8 files changed, 58 insertions(+), 126 deletions(-)
--- a/arch/arm/boot/compressed/efi-header.S
+++ b/arch/arm/boot/compressed/efi-header.S
@@ -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
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -1412,33 +1412,15 @@ __enter_kernel:
reloc_code_end:
#ifdef CONFIG_EFI_STUB
- .align 2
-_start: .long start - .
-
-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
+ENTRY(efi_enter_kernel)
+ mov r7, r0 @ preserve image base
+ mov r4, r1 @ preserve DT pointer
- @ 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
@@ -1448,9 +1430,8 @@ 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
@@ -1462,12 +1443,7 @@ 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
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -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.
- */
- 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).
+ * 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.
*/
- 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
--- a/arch/arm64/kernel/efi-header.S
+++ b/arch/arm64/kernel/efi-header.S
@@ -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:
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -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;
--- a/drivers/firmware/efi/libstub/arm-stub.c
+++ b/drivers/firmware/efi/libstub/arm-stub.c
@@ -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(unsigne
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, ef
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, ef
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, ef
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, ef
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, ef
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, ef
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, ef
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)
--- a/drivers/firmware/efi/libstub/arm32-stub.c
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -227,6 +227,7 @@ efi_status_t handle_kernel_image(unsigne
* 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);
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -49,7 +49,6 @@ efi_status_t handle_kernel_image(unsigne
{
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(unsigne
}
*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;
}