date:20180118

[PATCH V4 1/3] efi: Use efi_mm in x86 as well as ARM

2018-01-18 Thread Sai Praneeth Prakhya

From: Sai Praneeth 

Presently, only ARM uses mm_struct to manage efi page tables and efi
runtime region mappings. As this is the preferred approach, let's make
this data structure common across architectures. Specially, for x86,
using this data structure improves code maintainability and readability.

Signed-off-by: Sai Praneeth Prakhya 
Cc: Lee, Chun-Yi 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Cc: Ricardo Neri 
Cc: Matt Fleming 
Cc: Ard Biesheuvel 
Cc: Ravi Shankar 
Tested-by: Bhupesh Sharma 
---
 arch/x86/include/asm/efi.h | 4 
 arch/x86/platform/efi/efi_64.c | 3 +++
 drivers/firmware/efi/arm-runtime.c | 9 -
 drivers/firmware/efi/efi.c | 9 +
 include/linux/efi.h| 2 ++
 5 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 85f6ccb80b91..00f977ddd718 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -2,10 +2,14 @@
 #ifndef _ASM_X86_EFI_H
 #define _ASM_X86_EFI_H
 
+#include 
+#include 
+
 #include 
 #include 
 #include 
 #include 
+#include 
 
 /*
  * We map the EFI regions needed for runtime services non-contiguously,
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 2dd15e967c3f..c9f8e6924df7 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -232,6 +232,9 @@ int __init efi_alloc_page_tables(void)
return -ENOMEM;
}
 
+   mm_init_cpumask(_mm);
+   init_new_context(NULL, _mm);
+
return 0;
 }
 
diff --git a/drivers/firmware/efi/arm-runtime.c 
b/drivers/firmware/efi/arm-runtime.c
index 1cc41c3d6315..d6b26534812b 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -31,15 +31,6 @@
 
 extern u64 efi_system_table;
 
-static struct mm_struct efi_mm = {
-   .mm_rb  = RB_ROOT,
-   .mm_users   = ATOMIC_INIT(2),
-   .mm_count   = ATOMIC_INIT(1),
-   .mmap_sem   = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
-   .page_table_lock= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
-   .mmlist = LIST_HEAD_INIT(efi_mm.mmlist),
-};
-
 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
 #include 
 
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 557a47829d03..760260b933b6 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -74,6 +74,15 @@ static unsigned long *efi_tables[] = {
_attr_table,
 };
 
+struct mm_struct efi_mm = {
+   .mm_rb  = RB_ROOT,
+   .mm_users   = ATOMIC_INIT(2),
+   .mm_count   = ATOMIC_INIT(1),
+   .mmap_sem   = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
+   .page_table_lock= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
+   .mmlist = LIST_HEAD_INIT(efi_mm.mmlist),
+};
+
 static bool disable_runtime;
 static int __init setup_noefi(char *arg)
 {
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 29fdf8029cf6..d79f1cc4c8bb 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -930,6 +930,8 @@ extern struct efi {
unsigned long flags;
 } efi;
 
+extern struct mm_struct efi_mm;
+
 static inline int
 efi_guidcmp (efi_guid_t left, efi_guid_t right)
 {
-- 
2.1.4

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[PATCH V4 2/3] x86/efi: Replace efi_pgd with efi_mm.pgd

2018-01-18 Thread Sai Praneeth Prakhya

From: Sai Praneeth 

Since the previous patch added support for efi_mm, let's handle efi_pgd
through efi_mm and remove global variable efi_pgd.

Signed-off-by: Sai Praneeth Prakhya 
Cc: Lee, Chun-Yi 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Cc: Bhupesh Sharma 
Cc: Ricardo Neri 
Cc: Matt Fleming 
Cc: Ard Biesheuvel 
Cc: Ravi Shankar 
Tested-by: Bhupesh Sharma 
---
 arch/x86/platform/efi/efi_64.c | 17 -
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index c9f8e6924df7..c93f59731608 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -191,8 +191,6 @@ 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
@@ -204,7 +202,7 @@ static pgd_t *efi_pgd;
  */
 int __init efi_alloc_page_tables(void)
 {
-   pgd_t *pgd;
+   pgd_t *pgd, *efi_pgd;
p4d_t *p4d;
pud_t *pud;
gfp_t gfp_mask;
@@ -232,6 +230,7 @@ int __init efi_alloc_page_tables(void)
return -ENOMEM;
}
 
+   efi_mm.pgd = efi_pgd;
mm_init_cpumask(_mm);
init_new_context(NULL, _mm);
 
@@ -247,6 +246,7 @@ void efi_sync_low_kernel_mappings(void)
pgd_t *pgd_k, *pgd_efi;
p4d_t *p4d_k, *p4d_efi;
pud_t *pud_k, *pud_efi;
+   pgd_t *efi_pgd = efi_mm.pgd;
 
if (efi_enabled(EFI_OLD_MEMMAP))
return;
@@ -340,7 +340,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, 
unsigned num_pages)
unsigned long pfn, text, pf;
struct page *page;
unsigned npages;
-   pgd_t *pgd;
+   pgd_t *pgd = efi_mm.pgd;
 
if (efi_enabled(EFI_OLD_MEMMAP))
return 0;
@@ -350,8 +350,7 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, 
unsigned num_pages)
 * this value is loaded into cr3 the PGD will be decrypted during
 * the pagetable walk.
 */
-   efi_scratch.efi_pgt = (pgd_t *)__sme_pa(efi_pgd);
-   pgd = efi_pgd;
+   efi_scratch.efi_pgt = (pgd_t *)__sme_pa(pgd);
 
/*
 * It can happen that the physical address of new_memmap lands in memory
@@ -421,7 +420,7 @@ static void __init __map_region(efi_memory_desc_t *md, u64 
va)
 {
unsigned long flags = _PAGE_RW;
unsigned long pfn;
-   pgd_t *pgd = efi_pgd;
+   pgd_t *pgd = efi_mm.pgd;
 
if (!(md->attribute & EFI_MEMORY_WB))
flags |= _PAGE_PCD;
@@ -525,7 +524,7 @@ void __init parse_efi_setup(u64 phys_addr, u32 data_len)
 static int __init efi_update_mappings(efi_memory_desc_t *md, unsigned long pf)
 {
unsigned long pfn;
-   pgd_t *pgd = efi_pgd;
+   pgd_t *pgd = efi_mm.pgd;
int err1, err2;
 
/* Update the 1:1 mapping */
@@ -622,7 +621,7 @@ void __init efi_dump_pagetable(void)
if (efi_enabled(EFI_OLD_MEMMAP))
ptdump_walk_pgd_level(NULL, swapper_pg_dir);
else
-   ptdump_walk_pgd_level(NULL, efi_pgd);
+   ptdump_walk_pgd_level(NULL, efi_mm.pgd);
 #endif
 }
 
-- 
2.1.4

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[PATCH V4 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3

2018-01-18 Thread Sai Praneeth Prakhya

From: Sai Praneeth 

Use helper function (efi_switch_mm()) to switch to/from efi_mm. We
switch to efi_mm before calling
1. efi_set_virtual_address_map() and
2. Invoking any efi_runtime_service()

Likewise, we need to switch back to previous mm (mm context stolen by
efi_mm) after the above calls return successfully. We can use
efi_switch_mm() helper function only with x86_64 kernel and
"efi=old_map" disabled because, x86_32 and efi=old_map doesn't use
efi_pgd, rather they use swapper_pg_dir.

Signed-off-by: Sai Praneeth Prakhya 
Cc: Lee, Chun-Yi 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Cc: Bhupesh Sharma 
Cc: Ricardo Neri 
Cc: Matt Fleming 
Cc: Ard Biesheuvel 
Cc: Ravi Shankar 
Tested-by: Bhupesh Sharma 
---
 arch/x86/include/asm/efi.h   | 25 +-
 arch/x86/platform/efi/efi_64.c   | 40 +++-
 arch/x86/platform/efi/efi_thunk_64.S |  2 +-
 3 files changed, 32 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 00f977ddd718..cda9940bed7a 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -62,14 +62,13 @@ extern asmlinkage u64 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 - Scratch space used while switching to/from efi_mm
+ * @phys_stack: stack used during EFI Mixed Mode
+ * @prev_mm:store/restore stolen mm_struct while switching to/from efi_mm
  */
 struct efi_scratch {
-   u64 r15;
-   u64 prev_cr3;
-   pgd_t   *efi_pgt;
-   booluse_pgd;
-   u64 phys_stack;
+   u64 phys_stack;
+   struct mm_struct*prev_mm;
 } __packed;
 
 #define arch_efi_call_virt_setup() \
@@ -78,11 +77,8 @@ struct efi_scratch {
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();  \
-   }   \
+   if (!efi_enabled(EFI_OLD_MEMMAP))   \
+   efi_switch_mm(_mm); \
 })
 
 #define arch_efi_call_virt(p, f, args...)  \
@@ -90,10 +86,8 @@ struct efi_scratch {
 
 #define arch_efi_call_virt_teardown()  \
 ({ \
-   if (efi_scratch.use_pgd) {  \
-   write_cr3(efi_scratch.prev_cr3);\
-   __flush_tlb_all();  \
-   }   \
+   if (!efi_enabled(EFI_OLD_MEMMAP))   \
+   efi_switch_mm(efi_scratch.prev_mm); \
\
__kernel_fpu_end(); \
preempt_enable();   \
@@ -135,6 +129,7 @@ extern void __init efi_dump_pagetable(void);
 extern void __init efi_apply_memmap_quirks(void);
 extern int __init efi_reuse_config(u64 tables, int nr_tables);
 extern void efi_delete_dummy_variable(void);
+extern void efi_switch_mm(struct mm_struct *mm);
 
 struct efi_setup_data {
u64 fw_vendor;
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index c93f59731608..d6892ad2a693 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -82,9 +82,8 @@ pgd_t * __init efi_call_phys_prolog(void)
int n_pgds, i, j;
 
if (!efi_enabled(EFI_OLD_MEMMAP)) {
-   save_pgd = (pgd_t *)__read_cr3();
-   write_cr3((unsigned long)efi_scratch.efi_pgt);
-   goto out;
+   efi_switch_mm(_mm);
+   return NULL;
}
 
early_code_mapping_set_exec(1);
@@ -156,8 +155,7 @@ void __init efi_call_phys_epilog(pgd_t *save_pgd)
pud_t *pud;
 
if (!efi_enabled(EFI_OLD_MEMMAP)) {
-

[PATCH V4 0/3] Use mm_struct and switch_mm() instead of manually

2018-01-18 Thread Sai Praneeth Prakhya

From: Sai Praneeth 

Presently, in x86, to invoke any efi function like
efi_set_virtual_address_map() or any efi_runtime_service() the code path
typically involves read_cr3() (save previous pgd), write_cr3()
(write efi_pgd) and calling efi function. Likewise after returning from
efi function the code path typically involves read_cr3() (save efi_pgd),
write_cr3() (write previous pgd). We do this couple of times in efi
subsystem of Linux kernel, instead we can use helper function
efi_switch_mm() to do this. This improves readability and maintainability.
Also, instead of maintaining a separate struct "efi_scratch" to store/restore
efi_pgd, we can use mm_struct to do this.

I have tested this patch set against LUV (Linux UEFI Validation), so I
think I didn't break any existing configurations. I have tested this
patch set for
1. x86_64,
2. x86_32,
3. Mixed mode
with efi=old_map and for kexec kernel. Please let me know if I have
missed any other configurations.

Changes in V2:
1. Resolve mm_dropping() issue by not mm_dropping()/mm_grabbing() any mm,
as we are not losing/creating any references.

Changes in V3:
1. When CPUMASK_OFFSTACK is enabled, switch_mm_irqs_off() sets cpumask
by calling cpumask_set_cpu(). This panics kernel as efi_mm is not
initialized, therefore initialize efi_mm in efi_alloc_page_tables().

Changes in V4:
1. Remove the unintended removal of local_irq_restore(flags) (in 3rd patch).
IRQ flags should be restored after switching to orginal mm.

Note:
This patch set is based on Linus's tree v4.15-rc8

Sai Praneeth (3):
  efi: Use efi_mm in x86 as well as ARM
  x86/efi: Replace efi_pgd with efi_mm.pgd
  x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3

 arch/x86/include/asm/efi.h   | 29 +-
 arch/x86/platform/efi/efi_64.c   | 58 +++-
 arch/x86/platform/efi/efi_thunk_64.S |  2 +-
 drivers/firmware/efi/arm-runtime.c   |  9 --
 drivers/firmware/efi/efi.c   |  9 ++
 include/linux/efi.h  |  2 ++
 6 files changed, 57 insertions(+), 52 deletions(-)

Signed-off-by: Sai Praneeth Prakhya 
Cc: Lee, Chun-Yi 
Cc: Borislav Petkov 
Cc: Tony Luck 
Cc: Andy Lutomirski 
Cc: Michael S. Tsirkin 
Cc: Ricardo Neri 
Cc: Matt Fleming 
Cc: Ard Biesheuvel 
Cc: Ravi Shankar 
Tested-by: Bhupesh Sharma 

-- 
2.1.4

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[PATCH] efi: arm64: Check whether x18 is preserved by runtime services calls

2018-01-18 Thread Ard Biesheuvel

Whether or not we will ever decide to start using x18 as a platform
register in Linux is uncertain, but by that time, we will need to
ensure that UEFI runtime services calls don't corrupt it. So let's
start issuing warnings now for this, and increase the likelihood that
these firmware images have all been replaced by that time.

This has been fixed on the EDK2 side in commit 6d73863b5464
("BaseTools/tools_def AARCH64: mark register x18 as reserved").,
dated July 13, 2017.

Signed-off-by: Ard Biesheuvel 
---
 arch/arm64/include/asm/efi.h|  4 +++-
 drivers/firmware/efi/Makefile   |  2 +-
 drivers/firmware/efi/arm-runtime.c  | 10 +
 drivers/firmware/efi/arm64-rt-wrapper.S | 40 +
 4 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 drivers/firmware/efi/arm64-rt-wrapper.S

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 8389050328bb..2278e4bf270a 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -31,7 +31,7 @@ int efi_set_mapping_permissions(struct mm_struct *mm, 
efi_memory_desc_t *md);
 ({ \
efi_##f##_t *__f;   \
__f = p->f; \
-   __f(args);  \
+   __efi_rt_asm_wrapper(__f, args);\
 })
 
 #define arch_efi_call_virt_teardown()  \
@@ -40,6 +40,8 @@ int efi_set_mapping_permissions(struct mm_struct *mm, 
efi_memory_desc_t *md);
efi_virtmap_unload();   \
 })
 
+efi_status_t __efi_rt_asm_wrapper(void *, ...);
+
 #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
 
 /* arch specific definitions used by the stub code */
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 269501dfba53..eb8be0a00931 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -28,5 +28,5 @@ obj-$(CONFIG_APPLE_PROPERTIES)+= 
apple-properties.o
 
 arm-obj-$(CONFIG_EFI)  := arm-init.o arm-runtime.o
 obj-$(CONFIG_ARM)  += $(arm-obj-y)
-obj-$(CONFIG_ARM64)+= $(arm-obj-y)
+obj-$(CONFIG_ARM64)+= $(arm-obj-y) arm64-rt-wrapper.o
 obj-$(CONFIG_EFI_CAPSULE_LOADER)   += capsule-loader.o
diff --git a/drivers/firmware/efi/arm-runtime.c 
b/drivers/firmware/efi/arm-runtime.c
index 1cc41c3d6315..de84b490a844 100644
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -11,6 +11,8 @@
  *
  */
 
+#define pr_fmt(fmt)"efi: " fmt
+
 #include 
 #include 
 #include 
@@ -182,3 +184,11 @@ static int __init arm_dmi_init(void)
return 0;
 }
 core_initcall(arm_dmi_init);
+
+#ifdef CONFIG_ARM64
+efi_status_t efi_handle_corrupted_x18(efi_status_t s)
+{
+   pr_warn_ratelimited(FW_BUG "x18 corrupted by EFI firmware!");
+   return s;
+}
+#endif
diff --git a/drivers/firmware/efi/arm64-rt-wrapper.S 
b/drivers/firmware/efi/arm64-rt-wrapper.S
new file mode 100644
index ..a6a2b64134c9
--- /dev/null
+++ b/drivers/firmware/efi/arm64-rt-wrapper.S
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2018 Linaro Ltd 
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include 
+
+ENTRY(__efi_rt_asm_wrapper)
+   stp x29, x30, [sp, #-32]!
+   mov x29, sp
+
+   /*
+* Register x18 is designated as the 'platform' register by the AAPCS,
+* which means firmware running at the same exception level as the OS
+* (such as UEFI) should never touch it.
+*/
+   str x18, [sp, #16]
+
+   /*
+* We are lucky enough that no EFI runtime services take more than
+* 5 arguments, so all are passed in registers rather than via the
+* stack.
+*/
+   mov x8, x0
+   mov x0, x1
+   mov x1, x2
+   mov x2, x3
+   mov x3, x4
+   mov x4, x5
+   blr x8
+
+   ldr x1, [sp, #16]
+   cmp x1, x18
+   ldp x29, x30, [sp], #32
+   b.neefi_handle_corrupted_x18// tail call
+   ret
+ENDPROC(__efi_rt_asm_wrapper)
-- 
2.11.0

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[PATCH V4 1/3] efi: Use efi_mm in x86 as well as ARM

[PATCH V4 2/3] x86/efi: Replace efi_pgd with efi_mm.pgd

[PATCH V4 3/3] x86/efi: Use efi_switch_mm() rather than manually twiddling with %cr3

[PATCH V4 0/3] Use mm_struct and switch_mm() instead of manually

[PATCH] efi: arm64: Check whether x18 is preserved by runtime services calls

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