From 8acf63efa1712fa5495425a4224378bb3e1231e0 Mon Sep 17 00:00:00 2001 From: Arvind Sankar Date: Sun, 8 Mar 2020 09:08:43 +0100 Subject: [PATCH] efi/x86: Avoid using code32_start code32_start is meant for 16-bit real-mode bootloaders to inform the kernel where the 32-bit protected mode code starts. Nothing in the protected mode kernel except the EFI stub uses it. efi_main() currently returns boot_params, with code32_start set inside it to tell efi_stub_entry() where startup_32 is located. Since it was invoked by efi_stub_entry() in the first place, boot_params is already known. Return the address of startup_32 instead. This will allow a 64-bit kernel to live above 4Gb, for example, and it's cleaner as well. Signed-off-by: Arvind Sankar Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200301230436.2246909-5-nivedita@alum.mit.edu Link: https://lore.kernel.org/r/20200308080859.21568-13-ardb@kernel.org --- arch/x86/boot/compressed/head_32.S | 3 +-- arch/x86/boot/compressed/head_64.S | 4 ++-- arch/x86/kernel/asm-offsets.c | 1 - drivers/firmware/efi/libstub/x86-stub.c | 10 +++++----- 4 files changed, 8 insertions(+), 10 deletions(-) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 2f8138b..e013bdc 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -156,9 +156,8 @@ SYM_FUNC_END(startup_32) SYM_FUNC_START(efi32_stub_entry) SYM_FUNC_START_ALIAS(efi_stub_entry) add $0x4, %esp + movl 8(%esp), %esi /* save boot_params pointer */ call efi_main - movl %eax, %esi - movl BP_code32_start(%esi), %eax leal startup_32(%eax), %eax jmp *%eax SYM_FUNC_END(efi32_stub_entry) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index fabbd4c..6a4ff91 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -472,9 +472,9 @@ SYM_CODE_END(startup_64) SYM_FUNC_START(efi64_stub_entry) SYM_FUNC_START_ALIAS(efi_stub_entry) and $~0xf, %rsp /* realign the stack */ + movq %rdx, %rbx /* save boot_params pointer */ call efi_main - movq %rax,%rsi - movl BP_code32_start(%esi), %eax + movq %rbx,%rsi leaq startup_64(%rax), %rax jmp *%rax SYM_FUNC_END(efi64_stub_entry) diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 5c7ee3d..3ca07ad 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -88,7 +88,6 @@ static void __used common(void) OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment); OFFSET(BP_init_size, boot_params, hdr.init_size); OFFSET(BP_pref_address, boot_params, hdr.pref_address); - OFFSET(BP_code32_start, boot_params, hdr.code32_start); BLANK(); DEFINE(PTREGS_SIZE, sizeof(struct pt_regs)); diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 9db9883..7f3e97c 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -703,10 +703,11 @@ static efi_status_t exit_boot(struct boot_params *boot_params, void *handle) } /* - * On success we return a pointer to a boot_params structure, and NULL - * on failure. + * On success, we return the address of startup_32, which has potentially been + * relocated by efi_relocate_kernel. + * On failure, we exit to the firmware via efi_exit instead of returning. */ -struct boot_params *efi_main(efi_handle_t handle, +unsigned long efi_main(efi_handle_t handle, efi_system_table_t *sys_table_arg, struct boot_params *boot_params) { @@ -736,7 +737,6 @@ struct boot_params *efi_main(efi_handle_t handle, goto fail; } } - hdr->code32_start = (u32)bzimage_addr; /* * efi_pe_entry() may have been called before efi_main(), in which @@ -799,7 +799,7 @@ struct boot_params *efi_main(efi_handle_t handle, goto fail; } - return boot_params; + return bzimage_addr; fail: efi_printk("efi_main() failed!\n"); -- 2.7.4