From: Ingo Molnar Date: Thu, 21 Feb 2008 10:04:11 +0000 (+0100) Subject: x86: fix spontaneous reboot with allyesconfig bzImage X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=88f3aec7afd9ae3e6f6d221801996b69aad1e3a4;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git x86: fix spontaneous reboot with allyesconfig bzImage recently the 64-bit allyesconfig bzImage kernel started spontaneously rebooting during early bootup. after a few fun hours spent with early init debugging, it turns out that we've got this rather annoying limit on the size of the kernel image: #define KERNEL_TEXT_SIZE (40*1024*1024) which limit my vmlinux just happened to pass: text data bss dec hex filename 29703744 4222751 8646224 42572719 2899baf vmlinux 40 MB is 42572719 bytes, so my vmlinux was just 1.5% above this limit :-/ So it happily crashed right in head_64.S, which - as we all know - is the most debuggable code in the whole architecture ;-) So increase the limit to allow an up to 128MB kernel image to be mapped. (should anyone be that crazy or lazy) We have a full 4K of pagetable (level2_kernel_pgt) allocated for these mappings already, so there's no RAM overhead and the limit was rather pointless and arbitrary. Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index eb415043a929..b037b15be7f8 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -379,18 +379,24 @@ NEXT_PAGE(level2_ident_pgt) /* Since I easily can, map the first 1G. * Don't set NX because code runs from these pages. */ - PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) + PMDS(0, __PAGE_KERNEL_LARGE_EXEC, PTRS_PER_PMD) NEXT_PAGE(level2_kernel_pgt) - /* 40MB kernel mapping. The kernel code cannot be bigger than that. - When you change this change KERNEL_TEXT_SIZE in page.h too. */ - /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */ - PMDS(0x0000000000000000, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL, KERNEL_TEXT_SIZE/PMD_SIZE) - /* Module mapping starts here */ - .fill (PTRS_PER_PMD - (KERNEL_TEXT_SIZE/PMD_SIZE)),8,0 + /* + * 128 MB kernel mapping. We spend a full page on this pagetable + * anyway. + * + * The kernel code+data+bss must not be bigger than that. + * + * (NOTE: at +128MB starts the module area, see MODULES_VADDR. + * If you want to increase this then increase MODULES_VADDR + * too.) + */ + PMDS(0, __PAGE_KERNEL_LARGE_EXEC|_PAGE_GLOBAL, + KERNEL_TEXT_SIZE/PMD_SIZE) NEXT_PAGE(level2_spare_pgt) - .fill 512,8,0 + .fill 512, 8, 0 #undef PMDS #undef NEXT_PAGE diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 6dbb0035c57a..a02a14f0f324 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -172,8 +172,9 @@ set_pte_phys(unsigned long vaddr, unsigned long phys, pgprot_t prot) } /* - * The head.S code sets up the kernel high mapping from: - * __START_KERNEL_map to __START_KERNEL_map + KERNEL_TEXT_SIZE + * The head.S code sets up the kernel high mapping: + * + * from __START_KERNEL_map to __START_KERNEL_map + size (== _end-_text) * * phys_addr holds the negative offset to the kernel, which is added * to the compile time generated pmds. This results in invalid pmds up diff --git a/include/asm-x86/page_64.h b/include/asm-x86/page_64.h index f7393bc516ef..3e2e3ca63048 100644 --- a/include/asm-x86/page_64.h +++ b/include/asm-x86/page_64.h @@ -47,8 +47,12 @@ #define __PHYSICAL_MASK_SHIFT 46 #define __VIRTUAL_MASK_SHIFT 48 -#define KERNEL_TEXT_SIZE (40*1024*1024) -#define KERNEL_TEXT_START _AC(0xffffffff80000000, UL) +/* + * Kernel image size is limited to 128 MB (see level2_kernel_pgt in + * arch/x86/kernel/head_64.S), and it is mapped here: + */ +#define KERNEL_TEXT_SIZE (128*1024*1024) +#define KERNEL_TEXT_START _AC(0xffffffff80000000, UL) #ifndef __ASSEMBLY__ void clear_page(void *page);