| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <201101041720.54535.rusty@rustcorp.com.au> Date: Tue, 4 Jan 2011 17:20:54 +1030 From: Rusty Russell <rusty@...tcorp.com.au> To: x86@...nel.org, Ingo Molnar <mingo@...e.hu> Cc: linux-kernel@...r.kernel.org, lguest <lguest@...abs.org>, Jeremy Fitzhardinge <jeremy@...p.org> Subject: Re: [PATCH] x86: initialize initial_page_table before paravirt jumps On Wed, 22 Dec 2010 12:59:00 pm Rusty Russell wrote: > v2.6.36-rc8-54-gb40827f (x86-32, mm: Add an initial page table for > core bootstrapping) made x86 boot using initial_page_table and broke > lguest. > > For 2.6.37 we simply cut & paste the initialization code into lguest > (da32dac10126 "lguest: populate initial_page_table"), now we fix it > properly by doing that initialization before the paravirt jump. Ping? Ingo? I don't see this in -tip... Thanks, Rusty. Subject: x86: initialize initial_page_table before paravirt jumps v2.6.36-rc8-54-gb40827f (x86-32, mm: Add an initial page table for core bootstrapping) made x86 boot using initial_page_table and broke lguest. For 2.6.37 we simply cut & paste the initialization code into lguest (da32dac10126 "lguest: populate initial_page_table"), now we fix it properly by doing that initialization before the paravirt jump. Signed-off-by: Rusty Russell <rusty@...tcorp.com.au> Acked-by: Jeremy Fitzhardinge <jeremy@...p.org> --- arch/x86/kernel/head_32.S | 77 ++++++++++++++++---------------- arch/x86/lguest/i386_head.S | 105 -------------------------------------------- 2 files changed, 39 insertions(+), 143 deletions(-) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -139,39 +139,6 @@ 1: movl %eax, pa(olpc_ofw_pgd) #endif -#ifdef CONFIG_PARAVIRT - /* This is can only trip for a broken bootloader... */ - cmpw $0x207, pa(boot_params + BP_version) - jb default_entry - - /* Paravirt-compatible boot parameters. Look to see what architecture - we're booting under. */ - movl pa(boot_params + BP_hardware_subarch), %eax - cmpl $num_subarch_entries, %eax - jae bad_subarch - - movl pa(subarch_entries)(,%eax,4), %eax - subl $__PAGE_OFFSET, %eax - jmp *%eax - -bad_subarch: -WEAK(lguest_entry) -WEAK(xen_entry) - /* Unknown implementation; there's really - nothing we can do at this point. */ - ud2a - - __INITDATA - -subarch_entries: - .long default_entry /* normal x86/PC */ - .long lguest_entry /* lguest hypervisor */ - .long xen_entry /* Xen hypervisor */ - .long default_entry /* Moorestown MID */ -num_subarch_entries = (. - subarch_entries) / 4 -.previous -#endif /* CONFIG_PARAVIRT */ - /* * Initialize page tables. This creates a PDE and a set of page * tables, which are located immediately beyond __brk_base. The variable @@ -181,7 +148,6 @@ num_subarch_entries = (. - subarch_entri * * Note that the stack is not yet set up! */ -default_entry: #ifdef CONFIG_X86_PAE /* @@ -261,7 +227,42 @@ 11: movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax movl %eax,pa(initial_page_table+0xffc) #endif - jmp 3f + +#ifdef CONFIG_PARAVIRT + /* This is can only trip for a broken bootloader... */ + cmpw $0x207, pa(boot_params + BP_version) + jb default_entry + + /* Paravirt-compatible boot parameters. Look to see what architecture + we're booting under. */ + movl pa(boot_params + BP_hardware_subarch), %eax + cmpl $num_subarch_entries, %eax + jae bad_subarch + + movl pa(subarch_entries)(,%eax,4), %eax + subl $__PAGE_OFFSET, %eax + jmp *%eax + +bad_subarch: +WEAK(lguest_entry) +WEAK(xen_entry) + /* Unknown implementation; there's really + nothing we can do at this point. */ + ud2a + + __INITDATA + +subarch_entries: + .long default_entry /* normal x86/PC */ + .long lguest_entry /* lguest hypervisor */ + .long xen_entry /* Xen hypervisor */ + .long default_entry /* Moorestown MID */ +num_subarch_entries = (. - subarch_entries) / 4 +.previous +#else + jmp default_entry +#endif /* CONFIG_PARAVIRT */ + /* * Non-boot CPU entry point; entered from trampoline.S * We can't lgdt here, because lgdt itself uses a data segment, but @@ -282,7 +283,7 @@ ENTRY(startup_32_smp) movl %eax,%fs movl %eax,%gs #endif /* CONFIG_SMP */ -3: +default_entry: /* * New page tables may be in 4Mbyte page mode and may @@ -622,13 +623,13 @@ ENTRY(initial_code) __PAGE_ALIGNED_BSS .align PAGE_SIZE_asm #ifdef CONFIG_X86_PAE -ENTRY(initial_pg_pmd) +initial_pg_pmd: .fill 1024*KPMDS,4,0 #else ENTRY(initial_page_table) .fill 1024,4,0 #endif -ENTRY(initial_pg_fixmap) +initial_pg_fixmap: .fill 1024,4,0 ENTRY(empty_zero_page) .fill 4096,1,0 diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -4,7 +4,6 @@ #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/processor-flags.h> -#include <asm/pgtable.h> /*G:020 * Our story starts with the kernel booting into startup_32 in @@ -38,113 +37,9 @@ ENTRY(lguest_entry) /* Set up the initial stack so we can run C code. */ movl $(init_thread_union+THREAD_SIZE),%esp - call init_pagetables - /* Jumps are relative: we're running __PAGE_OFFSET too low. */ jmp lguest_init+__PAGE_OFFSET -/* - * Initialize page tables. This creates a PDE and a set of page - * tables, which are located immediately beyond __brk_base. The variable - * _brk_end is set up to point to the first "safe" location. - * Mappings are created both at virtual address 0 (identity mapping) - * and PAGE_OFFSET for up to _end. - * - * FIXME: This code is taken verbatim from arch/x86/kernel/head_32.S: they - * don't have a stack at this point, so we can't just use call and ret. - */ -init_pagetables: -#if PTRS_PER_PMD > 1 -#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD) -#else -#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD) -#endif -#define pa(X) ((X) - __PAGE_OFFSET) - -/* Enough space to fit pagetables for the low memory linear map */ -MAPPING_BEYOND_END = \ - PAGE_TABLE_SIZE(((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT) << PAGE_SHIFT -#ifdef CONFIG_X86_PAE - - /* - * In PAE mode initial_page_table is statically defined to contain - * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3 - * entries). The identity mapping is handled by pointing two PGD entries - * to the first kernel PMD. - * - * Note the upper half of each PMD or PTE are always zero at this stage. - */ - -#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */ - - xorl %ebx,%ebx /* %ebx is kept at zero */ - - movl $pa(__brk_base), %edi - movl $pa(initial_pg_pmd), %edx - movl $PTE_IDENT_ATTR, %eax -10: - leal PDE_IDENT_ATTR(%edi),%ecx /* Create PMD entry */ - movl %ecx,(%edx) /* Store PMD entry */ - /* Upper half already zero */ - addl $8,%edx - movl $512,%ecx -11: - stosl - xchgl %eax,%ebx - stosl - xchgl %eax,%ebx - addl $0x1000,%eax - loop 11b - - /* - * End condition: we must map up to the end + MAPPING_BEYOND_END. - */ - movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp - cmpl %ebp,%eax - jb 10b -1: - addl $__PAGE_OFFSET, %edi - movl %edi, pa(_brk_end) - shrl $12, %eax - movl %eax, pa(max_pfn_mapped) - - /* Do early initialization of the fixmap area */ - movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax - movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8) -#else /* Not PAE */ - -page_pde_offset = (__PAGE_OFFSET >> 20); - - movl $pa(__brk_base), %edi - movl $pa(initial_page_table), %edx - movl $PTE_IDENT_ATTR, %eax -10: - leal PDE_IDENT_ATTR(%edi),%ecx /* Create PDE entry */ - movl %ecx,(%edx) /* Store identity PDE entry */ - movl %ecx,page_pde_offset(%edx) /* Store kernel PDE entry */ - addl $4,%edx - movl $1024, %ecx -11: - stosl - addl $0x1000,%eax - loop 11b - /* - * End condition: we must map up to the end + MAPPING_BEYOND_END. - */ - movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp - cmpl %ebp,%eax - jb 10b - addl $__PAGE_OFFSET, %edi - movl %edi, pa(_brk_end) - shrl $12, %eax - movl %eax, pa(max_pfn_mapped) - - /* Do early initialization of the fixmap area */ - movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax - movl %eax,pa(initial_page_table+0xffc) -#endif - ret - /*G:055 * We create a macro which puts the assembler code between lgstart_ and lgend_ * markers. These templates are put in the .text section: they can't be -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists