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Shutemov" , Linus Torvalds , Joerg Roedel Subject: [PATCH v4 02/21] x86/efistub: Simplify and clean up handover entry code Date: Fri, 2 Jun 2023 12:12:54 +0200 Message-Id: <20230602101313.3557775-3-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230602101313.3557775-1-ardb@kernel.org> References: <20230602101313.3557775-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7508; i=ardb@kernel.org; h=from:subject; bh=6vIoJTudACrMHaUZpEmA9kKzuuAA0lBBUtfzLDgP/Vg=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIaXywMI/xWdftd5W1Ti0skFl44qdD6xDGlvOaew6xSowt /1M7bKVHaUsDGIcDLJiiiwCs/++23l6olSt8yxZmDmsTCBDGLg4BWAiMucYGW7nBm2VDizK9tJo 0rxft+L47YZdLmv54j4nHXx7IovdQoGRYU5ikSNT4RX+S3fOf7Ooda2+btKRHtksrPvvpP3JT6q XeAA= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Spam-Status: No, score=-4.6 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1767586852600741892?= X-GMAIL-MSGID: =?utf-8?q?1767586852600741892?= Now that the EFI entry code in assembler is only used by the optional and deprecated EFI handover protocol, and given that the EFI stub C code no longer returns to it, most of it can simply be dropped. While at it, clarify the symbol naming, by merging efi_main() and efi_stub_entry(), making the latter the shared entry point for all different boot modes that enter via the EFI stub. The efi32_stub_entry() and efi64_stub_entry() names are referenced explicitly by the tooling that populates the setup header, so these must be retained, but can be emitted as aliases of efi_stub_entry() where appropriate. Signed-off-by: Ard Biesheuvel --- Documentation/arch/x86/boot.rst | 2 +- arch/x86/boot/compressed/efi_mixed.S | 22 +++++++++++--------- arch/x86/boot/compressed/head_32.S | 11 ---------- arch/x86/boot/compressed/head_64.S | 12 ++--------- drivers/firmware/efi/libstub/x86-stub.c | 20 ++++++++++++++---- 5 files changed, 31 insertions(+), 36 deletions(-) diff --git a/Documentation/arch/x86/boot.rst b/Documentation/arch/x86/boot.rst index 33520ecdb37abfda..cdbca15a4fc23833 100644 --- a/Documentation/arch/x86/boot.rst +++ b/Documentation/arch/x86/boot.rst @@ -1417,7 +1417,7 @@ execution context provided by the EFI firmware. The function prototype for the handover entry point looks like this:: - efi_main(void *handle, efi_system_table_t *table, struct boot_params *bp) + efi_stub_entry(void *handle, efi_system_table_t *table, struct boot_params *bp) 'handle' is the EFI image handle passed to the boot loader by the EFI firmware, 'table' is the EFI system table - these are the first two diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S index 4ca70bf93dc0bdcd..dcc562c8f7f35162 100644 --- a/arch/x86/boot/compressed/efi_mixed.S +++ b/arch/x86/boot/compressed/efi_mixed.S @@ -26,8 +26,8 @@ * When booting in 64-bit mode on 32-bit EFI firmware, startup_64_mixed_mode() * is the first thing that runs after switching to long mode. Depending on * whether the EFI handover protocol or the compat entry point was used to - * enter the kernel, it will either branch to the 64-bit EFI handover - * entrypoint at offset 0x390 in the image, or to the 64-bit EFI PE/COFF + * enter the kernel, it will either branch to the common 64-bit EFI stub + * entrypoint efi_stub_entry() directly, or via the 64-bit EFI PE/COFF * entrypoint efi_pe_entry(). In the former case, the bootloader must provide a * struct bootparams pointer as the third argument, so the presence of such a * pointer is used to disambiguate. @@ -37,21 +37,23 @@ * | efi32_pe_entry |---->| | | +-----------+--+ * +------------------+ | | +------+----------------+ | * | startup_32 |---->| startup_64_mixed_mode | | - * +------------------+ | | +------+----------------+ V - * | efi32_stub_entry |---->| | | +------------------+ - * +------------------+ +------------+ +---->| efi64_stub_entry | - * +-------------+----+ - * +------------+ +----------+ | - * | startup_64 |<----| efi_main |<--------------+ - * +------------+ +----------+ + * +------------------+ | | +------+----------------+ | + * | efi32_stub_entry |---->| | | | + * +------------------+ +------------+ | | + * V | + * +------------+ +----------------+ | + * | startup_64 |<----| efi_stub_entry |<--------+ + * +------------+ +----------------+ */ SYM_FUNC_START(startup_64_mixed_mode) lea efi32_boot_args(%rip), %rdx mov 0(%rdx), %edi mov 4(%rdx), %esi +#ifdef CONFIG_EFI_HANDOVER_PROTOCOL mov 8(%rdx), %edx // saved bootparams pointer test %edx, %edx - jnz efi64_stub_entry + jnz efi_stub_entry +#endif /* * efi_pe_entry uses MS calling convention, which requires 32 bytes of * shadow space on the stack even if all arguments are passed in diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 987ae727cf9f0d04..8876ffe30e9a4819 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -150,17 +150,6 @@ SYM_FUNC_START(startup_32) jmp *%eax SYM_FUNC_END(startup_32) -#ifdef CONFIG_EFI_STUB -SYM_FUNC_START(efi32_stub_entry) - add $0x4, %esp - movl 8(%esp), %esi /* save boot_params pointer */ - call efi_main - /* efi_main returns the possibly relocated address of startup_32 */ - jmp *%eax -SYM_FUNC_END(efi32_stub_entry) -SYM_FUNC_ALIAS(efi_stub_entry, efi32_stub_entry) -#endif - .text SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 03c4328a88cbd5d0..71c1f40a7ac067b9 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -523,19 +523,11 @@ trampoline_return: jmp *%rax SYM_CODE_END(startup_64) -#ifdef CONFIG_EFI_STUB -#ifdef CONFIG_EFI_HANDOVER_PROTOCOL +#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL) .org 0x390 -#endif SYM_FUNC_START(efi64_stub_entry) - and $~0xf, %rsp /* realign the stack */ - movq %rdx, %rbx /* save boot_params pointer */ - call efi_main - movq %rbx,%rsi - leaq rva(startup_64)(%rax), %rax - jmp *%rax + jmp efi_stub_entry SYM_FUNC_END(efi64_stub_entry) -SYM_FUNC_ALIAS(efi_stub_entry, efi64_stub_entry) #endif .text diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 095aaa8b0ee30fb9..d6a376e52cbe1399 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -782,9 +782,9 @@ static void __noreturn enter_kernel(unsigned long kernel_addr, * On success, we jump to the relocated kernel directly and never return. * On failure, we exit to the firmware via efi_exit instead of returning. */ -asmlinkage unsigned long efi_main(efi_handle_t handle, - efi_system_table_t *sys_table_arg, - struct boot_params *boot_params) +void __noreturn efi_stub_entry(efi_handle_t handle, + efi_system_table_t *sys_table_arg, + struct boot_params *boot_params) { unsigned long bzimage_addr = (unsigned long)startup_32; unsigned long buffer_start, buffer_end; @@ -928,7 +928,19 @@ asmlinkage unsigned long efi_main(efi_handle_t handle, enter_kernel(bzimage_addr, boot_params); fail: - efi_err("efi_main() failed!\n"); + efi_err("efi_stub_entry() failed!\n"); efi_exit(handle, status); } + +#ifdef CONFIG_EFI_HANDOVER_PROTOCOL +#ifndef CONFIG_EFI_MIXED +extern __alias(efi_stub_entry) +void efi32_stub_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg, + struct boot_params *boot_params); + +extern __alias(efi_stub_entry) +void efi64_stub_entry(efi_handle_t handle, efi_system_table_t *sys_table_arg, + struct boot_params *boot_params); +#endif +#endif