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[amd64] efi: Build our own page table structure 

This avoids adding W+X pages to the default page table, which is not
only bad for security but also now triggers a warning on boot.
This commit is contained in:
Ben Hutchings 2016-02-15 22:56:18 +00:00
parent feb964cdac
commit 5b76884dc2
8 changed files with 893 additions and 0 deletions
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2
debian/changelog vendored
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@ -31,6 +31,8 @@ linux (4.4.1-1) UNRELEASED; urgency=medium
* udeb: Move most USB wireless drivers from nic-usb-modules to
nic-wireless-modules
* udeb: Really add virtio_input to virtio-modules (not input-modules)
* [x86] Fix issues resulting in W+X pages:
- [amd64] efi: Build our own page table structure
[ Roger Shimizu ]
* Enable TTY_PRINTK as module (Closes: #814540).

319
debian/patches/bugfix/x86/x86-efi-build-our-own-page-table-structures.patch vendored Normal file
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@ -0,0 +1,319 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 27 Nov 2015 21:09:34 +0000
Subject: [5/5] x86/efi: Build our own page table structures
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=67a9108ed4313b85a9c53406d80dc1ae3f8c3e36
With commit e1a58320a38d ("x86/mm: Warn on W^X mappings") all
users booting on 64-bit UEFI machines see the following warning,
------------[ cut here ]------------
WARNING: CPU: 7 PID: 1 at arch/x86/mm/dump_pagetables.c:225 note_page+0x5dc/0x780()
x86/mm: Found insecure W+X mapping at address ffff88000005f000/0xffff88000005f000
...
x86/mm: Checked W+X mappings: FAILED, 165660 W+X pages found.
...
This is caused by mapping EFI regions with RWX permissions.
There isn't much we can do to restrict the permissions for these
regions due to the way the firmware toolchains mix code and
data, but we can at least isolate these mappings so that they do
not appear in the regular kernel page tables.
In commit d2f7cbe7b26a ("x86/efi: Runtime services virtual
mapping") we started using 'trampoline_pgd' to map the EFI
regions because there was an existing identity mapping there
which we use during the SetVirtualAddressMap() call and for
broken firmware that accesses those addresses.
But 'trampoline_pgd' shares some PGD entries with
'swapper_pg_dir' and does not provide the isolation we require.
Notably the virtual address for __START_KERNEL_map and
MODULES_START are mapped by the same PGD entry so we need to be
more careful when copying changes over in
efi_sync_low_kernel_mappings().
This patch doesn't go the full mile, we still want to share some
PGD entries with 'swapper_pg_dir'. Having completely separate
page tables brings its own issues such as synchronising new
mappings after memory hotplug and module loading. Sharing also
keeps memory usage down.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: 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
Link: http://lkml.kernel.org/r/1448658575-17029-6-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.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, 102 insertions(+), 40 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 347eeacb06a8..8fd9e637629a 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -136,6 +136,7 @@ extern void __init efi_memory_uc(u64 addr, unsigned long size);
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);
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index ad285404ea7f..3c1f3cd7b2ba 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -869,7 +869,7 @@ static void __init kexec_enter_virtual_mode(void)
* 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
- * ->trampoline_pgd page table using a top-down VA allocation scheme.
+ * efi_pgd page table.
*
* 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_mode(void)
*
* 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 PGDs of the
- * kernel page table into ->trampoline_pgd prior to each call.
+ * function. For function arguments passing we do copy the PUDs of the
+ * kernel page table into efi_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
@@ -895,6 +895,12 @@ static void __init __efi_enter_virtual_mode(void)
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) {
@@ -954,28 +960,11 @@ static void __init __efi_enter_virtual_mode(void)
efi_runtime_mkexec();
/*
- * 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.
+ * 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.
*
* efi_cleanup_page_tables(__pa(new_memmap), 1 << pg_shift);
*/
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index ed5b67338294..58d669bc8250 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -38,6 +38,11 @@
* 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)
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index b19cdac959b2..4897f518760f 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -40,6 +40,7 @@
#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.
@@ -121,22 +122,92 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
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_pgds;
- pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
+ unsigned num_entries;
+ pgd_t *pgd_k, *pgd_efi;
+ pud_t *pud_k, *pud_efi;
if (efi_enabled(EFI_OLD_MEMMAP))
return;
- num_pgds = pgd_index(MODULES_END - 1) - pgd_index(PAGE_OFFSET);
+ /*
+ * 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);
- memcpy(pgd + pgd_index(PAGE_OFFSET),
- init_mm.pgd + pgd_index(PAGE_OFFSET),
- sizeof(pgd_t) * num_pgds);
+ /*
+ * 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);
+
+ 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);
}
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
@@ -150,8 +221,8 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
if (efi_enabled(EFI_OLD_MEMMAP))
return 0;
- efi_scratch.efi_pgt = (pgd_t *)(unsigned long)real_mode_header->trampoline_pgd;
- pgd = __va(efi_scratch.efi_pgt);
+ efi_scratch.efi_pgt = (pgd_t *)__pa(efi_pgd);
+ pgd = efi_pgd;
/*
* It can happen that the physical address of new_memmap lands in memory
@@ -216,16 +287,14 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
- pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
-
- kernel_unmap_pages_in_pgd(pgd, pa_memmap, num_pages);
+ kernel_unmap_pages_in_pgd(efi_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;
@@ -334,9 +403,7 @@ void __init efi_runtime_mkexec(void)
void __init efi_dump_pagetable(void)
{
#ifdef CONFIG_EFI_PGT_DUMP
- pgd_t *pgd = (pgd_t *)__va(real_mode_header->trampoline_pgd);
-
- ptdump_walk_pgd_level(NULL, pgd);
+ ptdump_walk_pgd_level(NULL, efi_pgd);
#endif
}

215
debian/patches/bugfix/x86/x86-efi-hoist-page-table-switching-code-into-efi_cal.patch vendored Normal file
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@ -0,0 +1,215 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 27 Nov 2015 21:09:33 +0000
Subject: [4/5] x86/efi: Hoist page table switching code into efi_call_virt()
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=c9f2a9a65e4855b74d92cdad688f6ee4a1a323ff
This change is a prerequisite for pending patches that switch to
a dedicated EFI page table, instead of using 'trampoline_pgd'
which shares PGD entries with 'swapper_pg_dir'. The pending
patches make it impossible to dereference the runtime service
function pointer without first switching %cr3.
It's true that we now have duplicated switching code in
efi_call_virt() and efi_call_phys_{prolog,epilog}() but we are
sacrificing code duplication for a little more clarity and the
ease of writing the page table switching code in C instead of
asm.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: 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
Link: http://lkml.kernel.org/r/1448658575-17029-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/efi.h | 25 +++++++++++++++++++++
arch/x86/platform/efi/efi_64.c | 24 ++++++++++-----------
arch/x86/platform/efi/efi_stub_64.S | 43 -------------------------------------
3 files changed, 36 insertions(+), 56 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 0010c78c4998..347eeacb06a8 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -3,6 +3,7 @@
#include <asm/fpu/api.h>
#include <asm/pgtable.h>
+#include <asm/tlb.h>
/*
* We map the EFI regions needed for runtime services non-contiguously,
@@ -64,6 +65,17 @@ extern u64 asmlinkage efi_call(void *fp, ...);
#define efi_call_phys(f, args...) efi_call((f), args)
+/*
+ * Scratch space used for switching the pagetable in the EFI stub
+ */
+struct efi_scratch {
+ u64 r15;
+ u64 prev_cr3;
+ pgd_t *efi_pgt;
+ bool use_pgd;
+ u64 phys_stack;
+} __packed;
+
#define efi_call_virt(f, ...) \
({ \
efi_status_t __s; \
@@ -71,7 +83,20 @@ extern u64 asmlinkage efi_call(void *fp, ...);
efi_sync_low_kernel_mappings(); \
preempt_disable(); \
__kernel_fpu_begin(); \
+ \
+ if (efi_scratch.use_pgd) { \
+ efi_scratch.prev_cr3 = read_cr3(); \
+ write_cr3((unsigned long)efi_scratch.efi_pgt); \
+ __flush_tlb_all(); \
+ } \
+ \
__s = efi_call((void *)efi.systab->runtime->f, __VA_ARGS__); \
+ \
+ if (efi_scratch.use_pgd) { \
+ write_cr3(efi_scratch.prev_cr3); \
+ __flush_tlb_all(); \
+ } \
+ \
__kernel_fpu_end(); \
preempt_enable(); \
__s; \
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 102976dda8c4..b19cdac959b2 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -47,16 +47,7 @@
*/
static u64 efi_va = EFI_VA_START;
-/*
- * Scratch space used for switching the pagetable in the EFI stub
- */
-struct efi_scratch {
- u64 r15;
- u64 prev_cr3;
- pgd_t *efi_pgt;
- bool use_pgd;
- u64 phys_stack;
-} __packed;
+struct efi_scratch efi_scratch;
static void __init early_code_mapping_set_exec(int executable)
{
@@ -83,8 +74,11 @@ pgd_t * __init efi_call_phys_prolog(void)
int pgd;
int n_pgds;
- if (!efi_enabled(EFI_OLD_MEMMAP))
- return NULL;
+ if (!efi_enabled(EFI_OLD_MEMMAP)) {
+ save_pgd = (pgd_t *)read_cr3();
+ write_cr3((unsigned long)efi_scratch.efi_pgt);
+ goto out;
+ }
early_code_mapping_set_exec(1);
@@ -96,6 +90,7 @@ pgd_t * __init efi_call_phys_prolog(void)
vaddress = (unsigned long)__va(pgd * PGDIR_SIZE);
set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress));
}
+out:
__flush_tlb_all();
return save_pgd;
@@ -109,8 +104,11 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
int pgd_idx;
int nr_pgds;
- if (!save_pgd)
+ if (!efi_enabled(EFI_OLD_MEMMAP)) {
+ write_cr3((unsigned long)save_pgd);
+ __flush_tlb_all();
return;
+ }
nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);
diff --git a/arch/x86/platform/efi/efi_stub_64.S b/arch/x86/platform/efi/efi_stub_64.S
index 86d0f9e08dd9..32020cb8bb08 100644
--- a/arch/x86/platform/efi/efi_stub_64.S
+++ b/arch/x86/platform/efi/efi_stub_64.S
@@ -38,41 +38,6 @@
mov %rsi, %cr0; \
mov (%rsp), %rsp
- /* stolen from gcc */
- .macro FLUSH_TLB_ALL
- movq %r15, efi_scratch(%rip)
- movq %r14, efi_scratch+8(%rip)
- movq %cr4, %r15
- movq %r15, %r14
- andb $0x7f, %r14b
- movq %r14, %cr4
- movq %r15, %cr4
- movq efi_scratch+8(%rip), %r14
- movq efi_scratch(%rip), %r15
- .endm
-
- .macro SWITCH_PGT
- cmpb $0, efi_scratch+24(%rip)
- je 1f
- movq %r15, efi_scratch(%rip) # r15
- # save previous CR3
- movq %cr3, %r15
- movq %r15, efi_scratch+8(%rip) # prev_cr3
- movq efi_scratch+16(%rip), %r15 # EFI pgt
- movq %r15, %cr3
- 1:
- .endm
-
- .macro RESTORE_PGT
- cmpb $0, efi_scratch+24(%rip)
- je 2f
- movq efi_scratch+8(%rip), %r15
- movq %r15, %cr3
- movq efi_scratch(%rip), %r15
- FLUSH_TLB_ALL
- 2:
- .endm
-
ENTRY(efi_call)
SAVE_XMM
mov (%rsp), %rax
@@ -83,16 +48,8 @@ ENTRY(efi_call)
mov %r8, %r9
mov %rcx, %r8
mov %rsi, %rcx
- SWITCH_PGT
call *%rdi
- RESTORE_PGT
addq $48, %rsp
RESTORE_XMM
ret
ENDPROC(efi_call)
-
- .data
-ENTRY(efi_scratch)
- .fill 3,8,0
- .byte 0
- .quad 0

71
debian/patches/bugfix/x86/x86-efi-map-ram-into-the-identity-page-table-for-mix.patch vendored Normal file
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@ -0,0 +1,71 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 27 Nov 2015 21:09:32 +0000
Subject: [3/5] x86/efi: Map RAM into the identity page table for mixed mode
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=b61a76f8850d2979550abc42d7e09154ebb8d785
We are relying on the pre-existing mappings in 'trampoline_pgd'
when accessing function arguments in the EFI mixed mode thunking
code.
Instead let's map memory explicitly so that things will continue
to work when we move to a separate page table in the future.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1448658575-17029-4-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/efi/efi_64.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 5aa186db59e3..102976dda8c4 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -144,6 +144,7 @@ void efi_sync_low_kernel_mappings(void)
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
unsigned long pfn, text;
+ efi_memory_desc_t *md;
struct page *page;
unsigned npages;
pgd_t *pgd;
@@ -177,6 +178,25 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
if (!IS_ENABLED(CONFIG_EFI_MIXED))
return 0;
+ /*
+ * Map all of RAM so that we can access arguments in the 1:1
+ * mapping when making EFI runtime calls.
+ */
+ for_each_efi_memory_desc(&memmap, md) {
+ if (md->type != EFI_CONVENTIONAL_MEMORY &&
+ md->type != EFI_LOADER_DATA &&
+ md->type != EFI_LOADER_CODE)
+ continue;
+
+ pfn = md->phys_addr >> PAGE_SHIFT;
+ npages = md->num_pages;
+
+ if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, npages, 0)) {
+ pr_err("Failed to map 1:1 memory\n");
+ return 1;
+ }
+ }
+
page = alloc_page(GFP_KERNEL|__GFP_DMA32);
if (!page)
panic("Unable to allocate EFI runtime stack < 4GB\n");

83
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@ -0,0 +1,83 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Thu, 21 Jan 2016 14:11:59 +0000
Subject: x86/efi: Setup separate EFI page tables in kexec paths
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=753b11ef8e92a1c1bbe97f2a5ec14bdd1ef2e6fe
The switch to using a new dedicated page table for EFI runtime
calls in commit commit 67a9108ed431 ("x86/efi: Build our own
page table structures") failed to take into account changes
required for the kexec code paths, which are unfortunately
duplicated in the EFI code.
Call the allocation and setup functions in
kexec_enter_virtual_mode() just like we do for
__efi_enter_virtual_mode() to avoid hitting NULL-pointer
dereferences when making EFI runtime calls.
At the very least, the call to efi_setup_page_tables() should
have existed for kexec before the following commit:
67a9108ed431 ("x86/efi: Build our own page table structures")
Things just magically worked because we were actually using
the kernel's page tables that contained the required mappings.
Reported-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
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: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1453385519-11477-1-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/efi/efi.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 3c1f3cd7b2ba..bdd9477f937c 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -815,6 +815,7 @@ static void __init kexec_enter_virtual_mode(void)
{
#ifdef CONFIG_KEXEC_CORE
efi_memory_desc_t *md;
+ unsigned int num_pages;
void *p;
efi.systab = NULL;
@@ -829,6 +830,12 @@ static void __init kexec_enter_virtual_mode(void)
return;
}
+ if (efi_alloc_page_tables()) {
+ pr_err("Failed to allocate EFI page tables\n");
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return;
+ }
+
/*
* Map efi regions which were passed via setup_data. The virt_addr is a
* fixed addr which was used in first kernel of a kexec boot.
@@ -843,6 +850,14 @@ static void __init kexec_enter_virtual_mode(void)
BUG_ON(!efi.systab);
+ num_pages = ALIGN(memmap.nr_map * memmap.desc_size, PAGE_SIZE);
+ num_pages >>= PAGE_SHIFT;
+
+ if (efi_setup_page_tables(memmap.phys_map, num_pages)) {
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return;
+ }
+
efi_sync_low_kernel_mappings();
/*

53
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@ -0,0 +1,53 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 27 Nov 2015 21:09:30 +0000
Subject: [1/5] x86/mm: Page align the '_end' symbol to avoid pfn conversion
bugs
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=21cdb6b568435738cc0b303b2b3b82742396310c
Ingo noted that if we can guarantee _end is aligned to PAGE_SIZE
we can automatically avoid bugs along the lines of,
size = _end - _text >> PAGE_SHIFT
which is missing a call to PFN_ALIGN(). The EFI mixed mode
contains this bug, for example.
_text is already aligned to PAGE_SIZE through the use of
LOAD_PHYSICAL_ADDR, and the BSS and BRK sections are explicitly
aligned in the linker script, so it makes sense to align _end to
match.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1448658575-17029-2-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e4bf11f562..4f1994257a18 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -325,6 +325,7 @@ SECTIONS
__brk_limit = .;
}
+ . = ALIGN(PAGE_SIZE);
_end = .;
STABS_DEBUG

144
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@ -0,0 +1,144 @@
From: Matt Fleming <matt@codeblueprint.co.uk>
Date: Fri, 27 Nov 2015 21:09:31 +0000
Subject: [2/5] x86/mm/pat: Ensure cpa->pfn only contains page frame numbers
Origin: https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/commit?id=edc3b9129cecd0f0857112136f5b8b1bc1d45918
The x86 pageattr code is confused about the data that is stored
in cpa->pfn, sometimes it's treated as a page frame number,
sometimes it's treated as an unshifted physical address, and in
one place it's treated as a pte.
The result of this is that the mapping functions do not map the
intended physical address.
This isn't a problem in practice because most of the addresses
we're mapping in the EFI code paths are already mapped in
'trampoline_pgd' and so the pageattr mapping functions don't
actually do anything in this case. But when we move to using a
separate page table for the EFI runtime this will be an issue.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1448658575-17029-3-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/pageattr.c | 17 ++++++-----------
arch/x86/platform/efi/efi_64.c | 16 ++++++++++------
2 files changed, 16 insertions(+), 17 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index a3137a4feed1..c70e42014101 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -905,15 +905,10 @@ static void populate_pte(struct cpa_data *cpa,
pte = pte_offset_kernel(pmd, start);
while (num_pages-- && start < end) {
-
- /* deal with the NX bit */
- if (!(pgprot_val(pgprot) & _PAGE_NX))
- cpa->pfn &= ~_PAGE_NX;
-
- set_pte(pte, pfn_pte(cpa->pfn >> PAGE_SHIFT, pgprot));
+ set_pte(pte, pfn_pte(cpa->pfn, pgprot));
start += PAGE_SIZE;
- cpa->pfn += PAGE_SIZE;
+ cpa->pfn++;
pte++;
}
}
@@ -969,11 +964,11 @@ static int populate_pmd(struct cpa_data *cpa,
pmd = pmd_offset(pud, start);
- set_pmd(pmd, __pmd(cpa->pfn | _PAGE_PSE |
+ set_pmd(pmd, __pmd(cpa->pfn << PAGE_SHIFT | _PAGE_PSE |
massage_pgprot(pmd_pgprot)));
start += PMD_SIZE;
- cpa->pfn += PMD_SIZE;
+ cpa->pfn += PMD_SIZE >> PAGE_SHIFT;
cur_pages += PMD_SIZE >> PAGE_SHIFT;
}
@@ -1042,11 +1037,11 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd,
* Map everything starting from the Gb boundary, possibly with 1G pages
*/
while (end - start >= PUD_SIZE) {
- set_pud(pud, __pud(cpa->pfn | _PAGE_PSE |
+ set_pud(pud, __pud(cpa->pfn << PAGE_SHIFT | _PAGE_PSE |
massage_pgprot(pud_pgprot)));
start += PUD_SIZE;
- cpa->pfn += PUD_SIZE;
+ cpa->pfn += PUD_SIZE >> PAGE_SHIFT;
cur_pages += PUD_SIZE >> PAGE_SHIFT;
pud++;
}
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index a0ac0f9c307f..5aa186db59e3 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -143,7 +143,7 @@ void efi_sync_low_kernel_mappings(void)
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
- unsigned long text;
+ unsigned long pfn, text;
struct page *page;
unsigned npages;
pgd_t *pgd;
@@ -160,7 +160,8 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
* and ident-map those pages containing the map before calling
* phys_efi_set_virtual_address_map().
*/
- if (kernel_map_pages_in_pgd(pgd, pa_memmap, pa_memmap, num_pages, _PAGE_NX)) {
+ pfn = pa_memmap >> PAGE_SHIFT;
+ if (kernel_map_pages_in_pgd(pgd, pfn, pa_memmap, num_pages, _PAGE_NX)) {
pr_err("Error ident-mapping new memmap (0x%lx)!\n", pa_memmap);
return 1;
}
@@ -185,8 +186,9 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
npages = (_end - _text) >> PAGE_SHIFT;
text = __pa(_text);
+ pfn = text >> PAGE_SHIFT;
- if (kernel_map_pages_in_pgd(pgd, text >> PAGE_SHIFT, text, npages, 0)) {
+ if (kernel_map_pages_in_pgd(pgd, pfn, text, npages, 0)) {
pr_err("Failed to map kernel text 1:1\n");
return 1;
}
@@ -204,12 +206,14 @@ void __init efi_cleanup_page_tables(unsigned long pa_memmap, unsigned 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 pf = 0;
+ unsigned long flags = 0;
+ unsigned long pfn;
if (!(md->attribute & EFI_MEMORY_WB))
- pf |= _PAGE_PCD;
+ flags |= _PAGE_PCD;
- if (kernel_map_pages_in_pgd(pgd, md->phys_addr, va, md->num_pages, pf))
+ pfn = md->phys_addr >> PAGE_SHIFT;
+ if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
md->phys_addr, va);
}

6
debian/patches/series vendored
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@ -124,3 +124,9 @@ bugfix/all/revert-workqueue-make-sure-delayed-work-run-in-local-cpu.patch
bugfix/all/af_unix-don-t-set-err-in-unix_stream_read_generic-unless-there-was-an-error.patch
bugfix/all/bpf-fix-branch-offset-adjustment-on-backjumps-after-.patch
bugfix/all/alsa-usb-audio-avoid-freeing-umidi-object-twice.patch
bugfix/x86/x86-mm-page-align-the-_end-symbol-to-avoid-pfn-conve.patch
bugfix/x86/x86-mm-pat-ensure-cpa-pfn-only-contains-page-frame-n.patch
bugfix/x86/x86-efi-map-ram-into-the-identity-page-table-for-mix.patch
bugfix/x86/x86-efi-hoist-page-table-switching-code-into-efi_cal.patch
bugfix/x86/x86-efi-build-our-own-page-table-structures.patch
bugfix/x86/x86-efi-setup-separate-efi-page-tables-in-kexec-path.patch