4.4-stable review patch. If anyone has any objections, please let me know.
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From: Greg Kroah-Hartman gregkh@linuxfoundation.org
This reverts commit 36e0f05afd4e1d09fd47936761a502aedbc50649 which is commit 67a9108ed4313b85a9c53406d80dc1ae3f8c3e36 upstream.
Turns there was too many other issues with this patch to make it viable for the stable tree.
Reported-by: Ben Hutchings ben.hutchings@codethink.co.uk Cc: Matt Fleming matt@codeblueprint.co.uk Cc: Borislav Petkov bp@suse.de Cc: Andrew Morton akpm@linux-foundation.org Cc: Andy Lutomirski luto@amacapital.net Cc: Andy Lutomirski luto@kernel.org Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Jones davej@codemonkey.org.uk Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Sai Praneeth Prakhya sai.praneeth.prakhya@intel.com Cc: Stephen Smalley sds@tycho.nsa.gov Cc: Thomas Gleixner tglx@linutronix.de Cc: Toshi Kani toshi.kani@hp.com Cc: linux-efi@vger.kernel.org Cc: Ingo Molnar mingo@kernel.org Cc: "Ghannam, Yazen" Yazen.Ghannam@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/efi.h | 1 arch/x86/platform/efi/efi.c | 39 ++++++++++------ arch/x86/platform/efi/efi_32.c | 5 -- arch/x86/platform/efi/efi_64.c | 97 ++++++----------------------------------- 4 files changed, 40 insertions(+), 102 deletions(-)
--- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -136,7 +136,6 @@ extern void __init efi_memory_uc(u64 add extern void __init efi_map_region(efi_memory_desc_t *md); extern void __init efi_map_region_fixed(efi_memory_desc_t *md); extern void efi_sync_low_kernel_mappings(void); -extern int __init efi_alloc_page_tables(void); extern int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages); extern void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages); extern void __init old_map_region(efi_memory_desc_t *md); --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -869,7 +869,7 @@ static void __init kexec_enter_virtual_m * This function will switch the EFI runtime services to virtual mode. * Essentially, we look through the EFI memmap and map every region that * has the runtime attribute bit set in its memory descriptor into the - * efi_pgd page table. + * ->trampoline_pgd page table using a top-down VA allocation scheme. * * The old method which used to update that memory descriptor with the * virtual address obtained from ioremap() is still supported when the @@ -879,8 +879,8 @@ static void __init kexec_enter_virtual_m * * The new method does a pagetable switch in a preemption-safe manner * so that we're in a different address space when calling a runtime - * function. For function arguments passing we do copy the PUDs of the - * kernel page table into efi_pgd prior to each call. + * function. For function arguments passing we do copy the PGDs of the + * kernel page table into ->trampoline_pgd prior to each call. * * Specially for kexec boot, efi runtime maps in previous kernel should * be passed in via setup_data. In that case runtime ranges will be mapped @@ -895,12 +895,6 @@ static void __init __efi_enter_virtual_m
efi.systab = NULL;
- if (efi_alloc_page_tables()) { - pr_err("Failed to allocate EFI page tables\n"); - clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); - return; - } - efi_merge_regions(); new_memmap = efi_map_regions(&count, &pg_shift); if (!new_memmap) { @@ -960,11 +954,28 @@ static void __init __efi_enter_virtual_m efi_runtime_mkexec();
/* - * We mapped the descriptor array into the EFI pagetable above - * but we're not unmapping it here because if we're running in - * EFI mixed mode we need all of memory to be accessible when - * we pass parameters to the EFI runtime services in the - * thunking code. + * We mapped the descriptor array into the EFI pagetable above but we're + * not unmapping it here. Here's why: + * + * We're copying select PGDs from the kernel page table to the EFI page + * table and when we do so and make changes to those PGDs like unmapping + * stuff from them, those changes appear in the kernel page table and we + * go boom. + * + * From setup_real_mode(): + * + * ... + * trampoline_pgd[0] = init_level4_pgt[pgd_index(__PAGE_OFFSET)].pgd; + * + * In this particular case, our allocation is in PGD 0 of the EFI page + * table but we've copied that PGD from PGD[272] of the EFI page table: + * + * pgd_index(__PAGE_OFFSET = 0xffff880000000000) = 272 + * + * where the direct memory mapping in kernel space is. + * + * new_memmap's VA comes from that direct mapping and thus clearing it, + * it would get cleared in the kernel page table too. * * efi_cleanup_page_tables(__pa(new_memmap), 1 << pg_shift); */ --- a/arch/x86/platform/efi/efi_32.c +++ b/arch/x86/platform/efi/efi_32.c @@ -38,11 +38,6 @@ * say 0 - 3G. */
-int __init efi_alloc_page_tables(void) -{ - return 0; -} - void efi_sync_low_kernel_mappings(void) {} void __init efi_dump_pagetable(void) {} int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -40,7 +40,6 @@ #include <asm/fixmap.h> #include <asm/realmode.h> #include <asm/time.h> -#include <asm/pgalloc.h>
/* * We allocate runtime services regions bottom-up, starting from -4G, i.e. @@ -122,92 +121,22 @@ void __init efi_call_phys_epilog(pgd_t * early_code_mapping_set_exec(0); }
-static pgd_t *efi_pgd; - -/* - * We need our own copy of the higher levels of the page tables - * because we want to avoid inserting EFI region mappings (EFI_VA_END - * to EFI_VA_START) into the standard kernel page tables. Everything - * else can be shared, see efi_sync_low_kernel_mappings(). - */ -int __init efi_alloc_page_tables(void) -{ - pgd_t *pgd; - pud_t *pud; - gfp_t gfp_mask; - - if (efi_enabled(EFI_OLD_MEMMAP)) - return 0; - - gfp_mask = GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO; - efi_pgd = (pgd_t *)__get_free_page(gfp_mask); - if (!efi_pgd) - return -ENOMEM; - - pgd = efi_pgd + pgd_index(EFI_VA_END); - - pud = pud_alloc_one(NULL, 0); - if (!pud) { - free_page((unsigned long)efi_pgd); - return -ENOMEM; - } - - pgd_populate(NULL, pgd, pud); - - return 0; -} - /* * Add low kernel mappings for passing arguments to EFI functions. */ void efi_sync_low_kernel_mappings(void) { - unsigned num_entries; - pgd_t *pgd_k, *pgd_efi; - pud_t *pud_k, *pud_efi; + unsigned num_pgds; + pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
if (efi_enabled(EFI_OLD_MEMMAP)) return;
- /* - * We can share all PGD entries apart from the one entry that - * covers the EFI runtime mapping space. - * - * Make sure the EFI runtime region mappings are guaranteed to - * only span a single PGD entry and that the entry also maps - * other important kernel regions. - */ - BUILD_BUG_ON(pgd_index(EFI_VA_END) != pgd_index(MODULES_END)); - BUILD_BUG_ON((EFI_VA_START & PGDIR_MASK) != - (EFI_VA_END & PGDIR_MASK)); - - pgd_efi = efi_pgd + pgd_index(PAGE_OFFSET); - pgd_k = pgd_offset_k(PAGE_OFFSET); - - num_entries = pgd_index(EFI_VA_END) - pgd_index(PAGE_OFFSET); - memcpy(pgd_efi, pgd_k, sizeof(pgd_t) * num_entries); - - /* - * We share all the PUD entries apart from those that map the - * EFI regions. Copy around them. - */ - BUILD_BUG_ON((EFI_VA_START & ~PUD_MASK) != 0); - BUILD_BUG_ON((EFI_VA_END & ~PUD_MASK) != 0); - - pgd_efi = efi_pgd + pgd_index(EFI_VA_END); - pud_efi = pud_offset(pgd_efi, 0); - - pgd_k = pgd_offset_k(EFI_VA_END); - pud_k = pud_offset(pgd_k, 0); - - num_entries = pud_index(EFI_VA_END); - memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries); + num_pgds = pgd_index(MODULES_END - 1) - pgd_index(PAGE_OFFSET);
- pud_efi = pud_offset(pgd_efi, EFI_VA_START); - pud_k = pud_offset(pgd_k, EFI_VA_START); - - num_entries = PTRS_PER_PUD - pud_index(EFI_VA_START); - memcpy(pud_efi, pud_k, sizeof(pud_t) * num_entries); + memcpy(pgd + pgd_index(PAGE_OFFSET), + init_mm.pgd + pgd_index(PAGE_OFFSET), + sizeof(pgd_t) * num_pgds); }
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) @@ -220,8 +149,8 @@ int __init efi_setup_page_tables(unsigne if (efi_enabled(EFI_OLD_MEMMAP)) return 0;
- efi_scratch.efi_pgt = (pgd_t *)__pa(efi_pgd); - pgd = efi_pgd; + efi_scratch.efi_pgt = (pgd_t *)(unsigned long)real_mode_header->trampoline_pgd; + pgd = __va(efi_scratch.efi_pgt);
/* * It can happen that the physical address of new_memmap lands in memory @@ -267,14 +196,16 @@ int __init efi_setup_page_tables(unsigne
void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages) { - kernel_unmap_pages_in_pgd(efi_pgd, pa_memmap, num_pages); + pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd); + + kernel_unmap_pages_in_pgd(pgd, pa_memmap, num_pages); }
static void __init __map_region(efi_memory_desc_t *md, u64 va) { + pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd); unsigned long flags = 0; unsigned long pfn; - pgd_t *pgd = efi_pgd;
if (!(md->attribute & EFI_MEMORY_WB)) flags |= _PAGE_PCD; @@ -383,7 +314,9 @@ void __init efi_runtime_mkexec(void) void __init efi_dump_pagetable(void) { #ifdef CONFIG_EFI_PGT_DUMP - ptdump_walk_pgd_level(NULL, efi_pgd); + pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd); + + ptdump_walk_pgd_level(NULL, pgd); #endif }