From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932456Ab2GAO4V (ORCPT ); Sun, 1 Jul 2012 10:56:21 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41444 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755722Ab2GAO4U (ORCPT ); Sun, 1 Jul 2012 10:56:20 -0400 Date: Sun, 1 Jul 2012 07:56:09 -0700 From: "tip-bot for Eric W. Biederman" Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, ebiederm@xmission.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, ebiederm@xmission.com In-Reply-To: <877gvob0g4.fsf_-_@xmission.com> References: <877gvob0g4.fsf_-_@xmission.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/boot] x86, boot: Optimize the elf header handling. Git-Commit-ID: ff63719a343a91678833ccd12636332f47ba94a9 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Sun, 01 Jul 2012 07:56:14 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: ff63719a343a91678833ccd12636332f47ba94a9 Gitweb: http://git.kernel.org/tip/ff63719a343a91678833ccd12636332f47ba94a9 Author: Eric W. Biederman AuthorDate: Sun, 3 Jun 2012 13:32:59 -0700 Committer: H. Peter Anvin CommitDate: Sat, 30 Jun 2012 19:20:54 -0700 x86, boot: Optimize the elf header handling. Create a space for the elf headers at the beginning of the kernels image in memory. Removing the need for an extra copy of the kernel during boot. Making things faster and making vmlinux smaller. - Allow room for the elf headers in the vmlinux. This removes the need to insert padding between the elf headers and the start of text. Reducing the size of vmlinux by 2MB on x86_64 and removing the need for parse_elf in boot.c to move the code. - Return the relocated entry point address from parse_elf as the kernel's entry point is no long at a fixed address. - Remove the now unnecessary copies in arch/x86/compress/misc.c:parse_elf The ELF headers are now guaranteed to not conflict with the program data in the uncompressed image. - In cleanup_highmap keep all pages starting with __START_KERNEL_map instead of _text. Those values used to be the same but with the insertion of the hole for the ELF headers they differ and cause us to nuke our first 2MB of text ouch! So use the __START_KERNEL_map which includes the elf headers. Signed-off-by: Eric W. Biederman Link: http://lkml.kernel.org/r/877gvob0g4.fsf_-_@xmission.com Signed-off-by: H. Peter Anvin --- arch/x86/boot/compressed/head_32.S | 2 +- arch/x86/boot/compressed/head_64.S | 2 +- arch/x86/boot/compressed/misc.c | 60 +++++++++++------------------------ arch/x86/kernel/vmlinux.lds.S | 4 +- arch/x86/mm/init_64.c | 3 +- 5 files changed, 25 insertions(+), 46 deletions(-) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index c85e3ac..1b15e2c 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -211,7 +211,7 @@ relocated: * Jump to the decompressed kernel. */ xorl %ebx, %ebx - jmp *%ebp + jmp *%eax /* * Stack and heap for uncompression diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 87e03a1..9b8d782 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -337,7 +337,7 @@ relocated: /* * Jump to the decompressed kernel. */ - jmp *%rbp + jmp *%rax .data gdt: diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 5b04b66..fc34e8a 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -198,23 +198,23 @@ static void error(char *x) asm("hlt"); } -static void parse_elf(void *output) +static void *parse_elf(void *output) { #ifdef CONFIG_X86_64 - Elf64_Ehdr ehdr; - Elf64_Phdr *phdrs, *phdr; + Elf64_Ehdr *ehdr; + Elf64_Phdr *phdrs; #else - Elf32_Ehdr ehdr; - Elf32_Phdr *phdrs, *phdr; + Elf32_Ehdr *ehdr; + Elf32_Phdr *phdrs; #endif void *dest; int i; - memcpy(&ehdr, output, sizeof(ehdr)); - if (ehdr.e_ident[EI_MAG0] != ELFMAG0 || - ehdr.e_ident[EI_MAG1] != ELFMAG1 || - ehdr.e_ident[EI_MAG2] != ELFMAG2 || - ehdr.e_ident[EI_MAG3] != ELFMAG3) { + ehdr = output; + if (ehdr->e_ident[EI_MAG0] != ELFMAG0 || + ehdr->e_ident[EI_MAG1] != ELFMAG1 || + ehdr->e_ident[EI_MAG2] != ELFMAG2 || + ehdr->e_ident[EI_MAG3] != ELFMAG3) { error("Kernel is not a valid ELF file"); return; } @@ -222,39 +222,17 @@ static void parse_elf(void *output) if (!quiet) putstr("Parsing ELF... "); - phdrs = malloc(sizeof(*phdrs) * ehdr.e_phnum); - if (!phdrs) - error("Failed to allocate space for phdrs"); + phdrs = output + ehdr->e_phoff; - memcpy(phdrs, output + ehdr.e_phoff, sizeof(*phdrs) * ehdr.e_phnum); - - for (i = 0; i < ehdr.e_phnum; i++) { - phdr = &phdrs[i]; - - switch (phdr->p_type) { - case PT_LOAD: -#ifdef CONFIG_RELOCATABLE - dest = output; - dest += (phdr->p_paddr - LOAD_PHYSICAL_ADDR); -#else - dest = (void *)(phdr->p_paddr); -#endif - memcpy(dest, - output + phdr->p_offset, - phdr->p_filesz); - break; - default: /* Ignore other PT_* */ break; - } - } - - free(phdrs); + return output + (ehdr->e_entry - LOAD_PHYSICAL_ADDR); } -asmlinkage void decompress_kernel(void *rmode, memptr heap, - unsigned char *input_data, - unsigned long input_len, - unsigned char *output) +asmlinkage void *decompress_kernel(void *rmode, memptr heap, + unsigned char *input_data, + unsigned long input_len, + unsigned char *output) { + void *entry; real_mode = rmode; if (cmdline_find_option_bool("quiet")) @@ -297,8 +275,8 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap, if (!quiet) putstr("\nDecompressing Linux... "); decompress(input_data, input_len, NULL, NULL, output, NULL, error); - parse_elf(output); + entry = parse_elf(output); if (!quiet) putstr("done.\nBooting the kernel.\n"); - return; + return entry; } diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 22a1530..af6fb8a 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -82,10 +82,10 @@ PHDRS { SECTIONS { #ifdef CONFIG_X86_32 - . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR; + . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR + SIZEOF_HEADERS; phys_startup_32 = startup_32 - LOAD_OFFSET; #else - . = __START_KERNEL; + . = __START_KERNEL + SIZEOF_HEADERS; phys_startup_64 = startup_64 - LOAD_OFFSET; #endif diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 2b6b4a3..e8599cd 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -303,13 +303,14 @@ void __init cleanup_highmap(void) { unsigned long vaddr = __START_KERNEL_map; unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT); + unsigned long text = __START_KERNEL_map; unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1; pmd_t *pmd = level2_kernel_pgt; for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) { if (pmd_none(*pmd)) continue; - if (vaddr < (unsigned long) _text || vaddr > end) + if (vaddr < text || vaddr > end) set_pmd(pmd, __pmd(0)); } }