Commit-ID: b8ff87a6158886771677e6dc8139bac6e3cba717
Gitweb: http://git.kernel.org/tip/b8ff87a6158886771677e6dc8139bac6e3cba717
Author: Matt Fleming <matt.fleming@xxxxxxxxx>
AuthorDate: Fri, 10 Jan 2014 15:54:31 +0000
Committer: Matt Fleming <matt.fleming@xxxxxxxxx>
CommitDate: Tue, 4 Mar 2014 21:25:06 +0000
x86/efi: Firmware agnostic handover entry points
The EFI handover code only works if the "bitness" of the firmware and
the kernel match, i.e. 64-bit firmware and 64-bit kernel - it is not
possible to mix the two. This goes against the tradition that a 32-bit
kernel can be loaded on a 64-bit BIOS platform without having to do
anything special in the boot loader. Linux distributions, for one thing,
regularly run only 32-bit kernels on their live media.
Despite having only one 'handover_offset' field in the kernel header,
EFI boot loaders use two separate entry points to enter the kernel based
on the architecture the boot loader was compiled for,
(1) 32-bit loader: handover_offset
(2) 64-bit loader: handover_offset + 512
Since we already have two entry points, we can leverage them to infer
the bitness of the firmware we're running on, without requiring any boot
loader modifications, by making (1) and (2) valid entry points for both
CONFIG_X86_32 and CONFIG_X86_64 kernels.
To be clear, a 32-bit boot loader will always use (1) and a 64-bit boot
loader will always use (2). It's just that, if a single kernel image
supports (1) and (2) that image can be used with both 32-bit and 64-bit
boot loaders, and hence both 32-bit and 64-bit EFI.
(1) and (2) must be 512 bytes apart at all times, but that is already
part of the boot ABI and we could never change that delta without
breaking existing boot loaders anyhow.
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
---
arch/x86/boot/Makefile | 2 +-
arch/x86/boot/compressed/eboot.c | 9 ++++--
arch/x86/boot/compressed/head_32.S | 2 +-
arch/x86/boot/compressed/head_64.S | 62 +++++++++++++++++++++++++++++++++-----
arch/x86/boot/tools/build.c | 22 +++++++++-----
arch/x86/include/asm/efi.h | 6 ++--
6 files changed, 80 insertions(+), 23 deletions(-)
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 878df7e..abb9eba 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -80,7 +80,7 @@ targets += voffset.h
$(obj)/voffset.h: vmlinux FORCE
$(call if_changed,voffset)
-sed-zoffset := -e 's/^\([0-9a-fA-F]*\) . \(startup_32\|startup_64\|efi_pe_entry\|efi_stub_entry\|input_data\|_end\|z_.*\)$$/\#define ZO_\2 0x\1/p'
+sed-zoffset := -e 's/^\([0-9a-fA-F]*\) . \(startup_32\|startup_64\|efi32_stub_entry\|efi64_stub_entry\|efi_pe_entry\|input_data\|_end\|z_.*\)$$/\#define ZO_\2 0x\1/p'
quiet_cmd_zoffset = ZOFFSET $@
cmd_zoffset = $(NM) $< | sed -n $(sed-zoffset) > $@
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index ab1f3a2..5e1ba4f 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -1256,12 +1256,13 @@ static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
}
static efi_status_t exit_boot(struct boot_params *boot_params,
- void *handle)
+ void *handle, bool is64)
{
struct efi_info *efi = &boot_params->efi_info;
unsigned long map_sz, key, desc_size;
efi_memory_desc_t *mem_map;
struct setup_data *e820ext;
+ const char *signature;
__u32 e820ext_size;
__u32 nr_desc, prev_nr_desc;
efi_status_t status;
@@ -1295,7 +1296,9 @@ get_map:
goto get_map; /* Allocated memory, get map again */
}
- memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
+ signature = is64 ? EFI64_LOADER_SIGNATURE : EFI32_LOADER_SIGNATURE;
+ memcpy(&efi->efi_loader_signature, signature, sizeof(__u32));
+
efi->efi_systab = (unsigned long)sys_table;
efi->efi_memdesc_size = desc_size;
efi->efi_memdesc_version = desc_version;
@@ -1408,7 +1411,7 @@ struct boot_params *efi_main(struct efi_config *c,
hdr->code32_start = bzimage_addr;
}
- status = exit_boot(boot_params, handle);
+ status = exit_boot(boot_params, handle, is64);
if (status != EFI_SUCCESS)
goto fail;
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index eed23c0..cccc05f 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -64,7 +64,7 @@ ENTRY(efi_pe_entry)
pushl %ecx
jmp 2f /* Skip efi_config initialization */
-ENTRY(efi_stub_entry)
+ENTRY(efi32_stub_entry)
add $0x4, %esp
popl %ecx
popl %edx
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 1bc206f..37c741b 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -178,6 +178,13 @@ ENTRY(startup_32)
*/
pushl $__KERNEL_CS
leal startup_64(%ebp), %eax
+#ifdef CONFIG_EFI_MIXED
+ movl efi32_config(%ebp), %ebx
+ cmp $0, %ebx
+ jz 1f
+ leal handover_entry(%ebp), %eax
+1:
+#endif
pushl %eax
/* Enter paged protected Mode, activating Long Mode */
@@ -188,6 +195,30 @@ ENTRY(startup_32)
lret
ENDPROC(startup_32)
+#ifdef CONFIG_EFI_MIXED
+ .org 0x190
+ENTRY(efi32_stub_entry)
+ add $0x4, %esp /* Discard return address */
+ popl %ecx
+ popl %edx
+ popl %esi
+
+ leal (BP_scratch+4)(%esi), %esp
+ call 1f
+1: pop %ebp
+ subl $1b, %ebp
+
+ movl %ecx, efi32_config(%ebp)
+ movl %edx, efi32_config+8(%ebp)
+ sgdtl efi32_boot_gdt(%ebp)
+
+ leal efi32_config(%ebp), %eax
+ movl %eax, efi_config(%ebp)
+
+ jmp startup_32
+ENDPROC(efi32_stub_entry)
+#endif
+
.code64
.org 0x200
ENTRY(startup_64)
@@ -231,13 +262,7 @@ ENTRY(efi_pe_entry)
mov %rax, %rsi
jmp 2f /* Skip the relocation */
-ENTRY(efi_stub_entry)
- movq %rdi, efi64_config(%rip) /* Handle */
- movq %rsi, efi64_config+8(%rip) /* EFI System table pointer */
-
- leaq efi64_config(%rip), %rax
- movq %rax, efi_config(%rip)
-
+handover_entry:
call 1f
1: popq %rbp
subq $1b, %rbp
@@ -247,7 +272,6 @@ ENTRY(efi_stub_entry)
*/
movq efi_config(%rip), %rax
addq %rbp, 88(%rax)
- movq %rdx, %rsi
2:
movq efi_config(%rip), %rdi
call efi_main
@@ -336,6 +360,20 @@ preferred_addr:
leaq relocated(%rbx), %rax
jmp *%rax
+#ifdef CONFIG_EFI_STUB
+ .org 0x390
+ENTRY(efi64_stub_entry)
+ movq %rdi, efi64_config(%rip) /* Handle */
+ movq %rsi, efi64_config+8(%rip) /* EFI System table pointer */
+
+ leaq efi64_config(%rip), %rax
+ movq %rax, efi_config(%rip)
+
+ movq %rdx, %rsi
+ jmp handover_entry
+ENDPROC(efi64_stub_entry)
+#endif
+
.text
relocated:
@@ -404,6 +442,14 @@ gdt_end:
efi_config:
.quad 0
+#ifdef CONFIG_EFI_MIXED
+ .global efi32_config
+efi32_config:
+ .fill 11,8,0
+ .quad efi64_thunk
+ .byte 0
+#endif
+
.global efi64_config
efi64_config:
.fill 11,8,0
diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index bf26207..4f07df5 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -53,7 +53,8 @@ int is_big_kernel;
#define PECOFF_RELOC_RESERVE 0x20
-unsigned long efi_stub_entry;
+unsigned long efi32_stub_entry;
+unsigned long efi64_stub_entry;
unsigned long efi_pe_entry;
unsigned long startup_64;
@@ -231,20 +232,26 @@ static void efi_stub_defaults(void)
/* Defaults for old kernel */
#ifdef CONFIG_X86_32
efi_pe_entry = 0x10;
- efi_stub_entry = 0x30;
#else
efi_pe_entry = 0x210;
- efi_stub_entry = 0x230;
startup_64 = 0x200;
#endif
}
static void efi_stub_entry_update(void)
{
-#ifdef CONFIG_X86_64 /* Yes, this is really how we defined it :( */
- efi_stub_entry -= 0x200;
+ unsigned long addr = efi32_stub_entry;
+
+#ifdef CONFIG_X86_64
+ /* Yes, this is really how we defined it :( */
+ addr = efi64_stub_entry - 0x200;
+#endif
+
+#ifdef CONFIG_EFI_MIXED
+ if (efi32_stub_entry != addr)
+ die("32-bit and 64-bit EFI entry points do not match\n");
#endif
- put_unaligned_le32(efi_stub_entry, &buf[0x264]);
+ put_unaligned_le32(addr, &buf[0x264]);
}
#else
@@ -289,7 +296,8 @@ static void parse_zoffset(char *fname)
p = (char *)buf;
while (p && *p) {
- PARSE_ZOFS(p, efi_stub_entry);
+ PARSE_ZOFS(p, efi32_stub_entry);
+ PARSE_ZOFS(p, efi64_stub_entry);
PARSE_ZOFS(p, efi_pe_entry);
PARSE_ZOFS(p, startup_64);
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 3d6b9f8..8585686 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -19,9 +19,11 @@
*/
#define EFI_OLD_MEMMAP EFI_ARCH_1
+#define EFI32_LOADER_SIGNATURE "EL32"
+#define EFI64_LOADER_SIGNATURE "EL64"
+
#ifdef CONFIG_X86_32
-#define EFI_LOADER_SIGNATURE "EL32"
extern unsigned long asmlinkage efi_call_phys(void *, ...);
@@ -57,8 +59,6 @@ extern unsigned long asmlinkage efi_call_phys(void *, ...);
#else /* !CONFIG_X86_32 */
-#define EFI_LOADER_SIGNATURE "EL64"
-
extern u64 efi_call0(void *fp);
extern u64 efi_call1(void *fp, u64 arg1);
extern u64 efi_call2(void *fp, u64 arg1, u64 arg2);
--
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