From 1ea34adb87c969b89dfd83f1905a79161e9ada26 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 26 May 2017 12:36:47 +0100 Subject: efi: Don't issue error message when booted under Xen When booted as Xen dom0 there won't be an EFI memmap allocated. Avoid issuing an error message in this case: [ 0.144079] efi: Failed to allocate new EFI memmap Signed-off-by: Juergen Gross Signed-off-by: Matt Fleming Cc: # v4.9+ Cc: Ard Biesheuvel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170526113652.21339-2-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/quirks.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch') diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c index 26615991d69c..e0cf95a83f3f 100644 --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -360,6 +360,9 @@ void __init efi_free_boot_services(void) free_bootmem_late(start, size); } + if (!num_entries) + return; + new_size = efi.memmap.desc_size * num_entries; new_phys = efi_memmap_alloc(num_entries); if (!new_phys) { -- cgit v1.2.3 From 4e52797d2efefac3271abdc54439a3435abd77b9 Mon Sep 17 00:00:00 2001 From: Sai Praneeth Date: Fri, 26 May 2017 12:36:49 +0100 Subject: x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map Booting kexec kernel with "efi=old_map" in kernel command line hits kernel panic as shown below. BUG: unable to handle kernel paging request at ffff88007fe78070 IP: virt_efi_set_variable.part.7+0x63/0x1b0 PGD 7ea28067 PUD 7ea2b067 PMD 7ea2d067 PTE 0 [...] Call Trace: virt_efi_set_variable() efi_delete_dummy_variable() efi_enter_virtual_mode() start_kernel() x86_64_start_reservations() x86_64_start_kernel() start_cpu() [ efi=old_map was never intended to work with kexec. The problem with using efi=old_map is that the virtual addresses are assigned from the memory region used by other kernel mappings; vmalloc() space. Potentially there could be collisions when booting kexec if something else is mapped at the virtual address we allocated for runtime service regions in the initial boot - Matt Fleming ] Since kexec was never intended to work with efi=old_map, disable runtime services in kexec if booted with efi=old_map, so that we don't panic. Tested-by: Lee Chun-Yi Signed-off-by: Sai Praneeth Prakhya Signed-off-by: Matt Fleming Acked-by: Dave Young Cc: Ard Biesheuvel Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Ravi Shankar Cc: Ricardo Neri Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170526113652.21339-4-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/efi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 7e76a4d8304b..43b96f5f78ba 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -828,9 +828,11 @@ static void __init kexec_enter_virtual_mode(void) /* * We don't do virtual mode, since we don't do runtime services, on - * non-native EFI + * non-native EFI. With efi=old_map, we don't do runtime services in + * kexec kernel because in the initial boot something else might + * have been mapped at these virtual addresses. */ - if (!efi_is_native()) { + if (!efi_is_native() || efi_enabled(EFI_OLD_MEMMAP)) { efi_memmap_unmap(); clear_bit(EFI_RUNTIME_SERVICES, &efi.flags); return; -- cgit v1.2.3 From 94133e46a0f5ca3f138479806104ab4a8cb0455e Mon Sep 17 00:00:00 2001 From: Baoquan He Date: Fri, 26 May 2017 12:36:50 +0100 Subject: x86/efi: Correct EFI identity mapping under 'efi=old_map' when KASLR is enabled For EFI with the 'efi=old_map' kernel option specified, the kernel will panic when KASLR is enabled: BUG: unable to handle kernel paging request at 000000007febd57e IP: 0x7febd57e PGD 1025a067 PUD 0 Oops: 0010 [#1] SMP Call Trace: efi_enter_virtual_mode() start_kernel() x86_64_start_reservations() x86_64_start_kernel() start_cpu() The root cause is that the identity mapping is not built correctly in the 'efi=old_map' case. On 'nokaslr' kernels, PAGE_OFFSET is 0xffff880000000000 which is PGDIR_SIZE aligned. We can borrow the PUD table from the direct mappings safely. Given a physical address X, we have pud_index(X) == pud_index(__va(X)). However, on KASLR kernels, PAGE_OFFSET is PUD_SIZE aligned. For a given physical address X, pud_index(X) != pud_index(__va(X)). We can't just copy the PGD entry from direct mapping to build identity mapping, instead we need to copy the PUD entries one by one from the direct mapping. Fix it. Signed-off-by: Baoquan He Signed-off-by: Matt Fleming Cc: Ard Biesheuvel Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Young Cc: Frank Ramsay Cc: Kees Cook Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Russ Anderson Cc: Thomas Garnier Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170526113652.21339-5-matt@codeblueprint.co.uk [ Fixed and reworded the changelog and code comments to be more readable. ] Signed-off-by: Ingo Molnar --- arch/x86/platform/efi/efi_64.c | 79 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 71 insertions(+), 8 deletions(-) (limited to 'arch') diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index c488625c9712..eb8dff15a7f6 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -71,11 +71,13 @@ static void __init early_code_mapping_set_exec(int executable) pgd_t * __init efi_call_phys_prolog(void) { - unsigned long vaddress; - pgd_t *save_pgd; + unsigned long vaddr, addr_pgd, addr_p4d, addr_pud; + pgd_t *save_pgd, *pgd_k, *pgd_efi; + p4d_t *p4d, *p4d_k, *p4d_efi; + pud_t *pud; int pgd; - int n_pgds; + int n_pgds, i, j; if (!efi_enabled(EFI_OLD_MEMMAP)) { save_pgd = (pgd_t *)read_cr3(); @@ -88,10 +90,49 @@ pgd_t * __init efi_call_phys_prolog(void) n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE); save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL); + /* + * Build 1:1 identity mapping for efi=old_map usage. Note that + * PAGE_OFFSET is PGDIR_SIZE aligned when KASLR is disabled, while + * it is PUD_SIZE ALIGNED with KASLR enabled. So for a given physical + * address X, the pud_index(X) != pud_index(__va(X)), we can only copy + * PUD entry of __va(X) to fill in pud entry of X to build 1:1 mapping. + * This means here we can only reuse the PMD tables of the direct mapping. + */ for (pgd = 0; pgd < n_pgds; pgd++) { - save_pgd[pgd] = *pgd_offset_k(pgd * PGDIR_SIZE); - vaddress = (unsigned long)__va(pgd * PGDIR_SIZE); - set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress)); + addr_pgd = (unsigned long)(pgd * PGDIR_SIZE); + vaddr = (unsigned long)__va(pgd * PGDIR_SIZE); + pgd_efi = pgd_offset_k(addr_pgd); + save_pgd[pgd] = *pgd_efi; + + p4d = p4d_alloc(&init_mm, pgd_efi, addr_pgd); + if (!p4d) { + pr_err("Failed to allocate p4d table!\n"); + goto out; + } + + for (i = 0; i < PTRS_PER_P4D; i++) { + addr_p4d = addr_pgd + i * P4D_SIZE; + p4d_efi = p4d + p4d_index(addr_p4d); + + pud = pud_alloc(&init_mm, p4d_efi, addr_p4d); + if (!pud) { + pr_err("Failed to allocate pud table!\n"); + goto out; + } + + for (j = 0; j < PTRS_PER_PUD; j++) { + addr_pud = addr_p4d + j * PUD_SIZE; + + if (addr_pud > (max_pfn << PAGE_SHIFT)) + break; + + vaddr = (unsigned long)__va(addr_pud); + + pgd_k = pgd_offset_k(vaddr); + p4d_k = p4d_offset(pgd_k, vaddr); + pud[j] = *pud_offset(p4d_k, vaddr); + } + } } out: __flush_tlb_all(); @@ -104,8 +145,11 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd) /* * After the lock is released, the original page table is restored. */ - int pgd_idx; + int pgd_idx, i; int nr_pgds; + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; if (!efi_enabled(EFI_OLD_MEMMAP)) { write_cr3((unsigned long)save_pgd); @@ -115,9 +159,28 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd) nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE); - for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++) + for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++) { + pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE); set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]); + if (!(pgd_val(*pgd) & _PAGE_PRESENT)) + continue; + + for (i = 0; i < PTRS_PER_P4D; i++) { + p4d = p4d_offset(pgd, + pgd_idx * PGDIR_SIZE + i * P4D_SIZE); + + if (!(p4d_val(*p4d) & _PAGE_PRESENT)) + continue; + + pud = (pud_t *)p4d_page_vaddr(*p4d); + pud_free(&init_mm, pud); + } + + p4d = (p4d_t *)pgd_page_vaddr(*pgd); + p4d_free(&init_mm, p4d); + } + kfree(save_pgd); __flush_tlb_all(); -- cgit v1.2.3