[RFC v2 10/10] x86: boot, extract efi_pe_entry from startup_64

From: Jiri Slaby
Date: Mon Mar 20 2017 - 08:35:04 EST


efi_pe_entry body is somehow squashed into startup_64. It makes the code
less readable and illogical. Extract the inlined efi_pe_entry body from
startup_64 into a separate function and mark it appropriatelly by
SYM_FUNC_START+SYM_FUNC_END.

ABI offsets are preserved:
0000000000000200 T startup_64
0000000000000280 T efi_pe_entry
00000000000002d0 t handover_entry
00000000000002fd t fail
0000000000000390 T efi64_stub_entry

Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <x86@xxxxxxxxxx>
---
arch/x86/boot/compressed/head_64.S | 112 ++++++++++++++++++-------------------
1 file changed, 53 insertions(+), 59 deletions(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 6f037b3af204..30f3c1117243 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -243,65 +243,6 @@ ENTRY(startup_64)
* that maps our entire kernel(text+data+bss+brk), zero page
* and command line.
*/
-#ifdef CONFIG_EFI_STUB
- /*
- * The entry point for the PE/COFF executable is efi_pe_entry, so
- * only legacy boot loaders will execute this jmp.
- */
- jmp preferred_addr
-
-SYM_FUNC_INNER_LABEL(efi_pe_entry)
- movq %rcx, efi64_config(%rip) /* Handle */
- movq %rdx, efi64_config+8(%rip) /* EFI System table pointer */
-
- leaq efi64_config(%rip), %rax
- movq %rax, efi_config(%rip)
-
- call 1f
-1: popq %rbp
- subq $1b, %rbp
-
- /*
- * Relocate efi_config->call().
- */
- addq %rbp, efi64_config+40(%rip)
-
- movq %rax, %rdi
- call make_boot_params
- cmpq $0,%rax
- je fail
- mov %rax, %rsi
- leaq startup_32(%rip), %rax
- movl %eax, BP_code32_start(%rsi)
- jmp 2f /* Skip the relocation */
-
-handover_entry:
- call 1f
-1: popq %rbp
- subq $1b, %rbp
-
- /*
- * Relocate efi_config->call().
- */
- movq efi_config(%rip), %rax
- addq %rbp, 40(%rax)
-2:
- movq efi_config(%rip), %rdi
- call efi_main
- movq %rax,%rsi
- cmpq $0,%rax
- jne 2f
-fail:
- /* EFI init failed, so hang. */
- hlt
- jmp fail
-2:
- movl BP_code32_start(%esi), %eax
- leaq preferred_addr(%rax), %rax
- jmp *%rax
-
-preferred_addr:
-#endif

/* Setup data segments. */
xorl %eax, %eax
@@ -372,6 +313,59 @@ preferred_addr:
SYM_FUNC_END(startup_64)

#ifdef CONFIG_EFI_STUB
+
+/* The entry point for the PE/COFF executable is efi_pe_entry. */
+SYM_FUNC_START(efi_pe_entry)
+ movq %rcx, efi64_config(%rip) /* Handle */
+ movq %rdx, efi64_config+8(%rip) /* EFI System table pointer */
+
+ leaq efi64_config(%rip), %rax
+ movq %rax, efi_config(%rip)
+
+ call 1f
+1: popq %rbp
+ subq $1b, %rbp
+
+ /*
+ * Relocate efi_config->call().
+ */
+ addq %rbp, efi64_config+40(%rip)
+
+ movq %rax, %rdi
+ call make_boot_params
+ cmpq $0,%rax
+ je fail
+ mov %rax, %rsi
+ leaq startup_32(%rip), %rax
+ movl %eax, BP_code32_start(%rsi)
+ jmp 2f /* Skip the relocation */
+
+handover_entry:
+ call 1f
+1: popq %rbp
+ subq $1b, %rbp
+
+ /*
+ * Relocate efi_config->call().
+ */
+ movq efi_config(%rip), %rax
+ addq %rbp, 40(%rax)
+2:
+ movq efi_config(%rip), %rdi
+ call efi_main
+ movq %rax,%rsi
+ cmpq $0,%rax
+ jne 2f
+fail:
+ /* EFI init failed, so hang. */
+ hlt
+ jmp fail
+2:
+ movl BP_code32_start(%esi), %eax
+ leaq startup_64(%rax), %rax
+ jmp *%rax
+SYM_FUNC_END(efi_pe_entry)
+
.org 0x390
ENTRY(efi64_stub_entry)
movq %rdi, efi64_config(%rip) /* Handle */
--
2.12.0