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* [PATCH 1/3] efi: Use efi_mm in x86 as well as ARM
@ 2017-12-17  0:06 Sai Praneeth Prakhya
  0 siblings, 0 replies; 2+ messages in thread
From: Sai Praneeth Prakhya @ 2017-12-17  0:06 UTC (permalink / raw)
  To: linux-efi, linux-kernel
  Cc: Sai Praneeth, Lee, Chun-Yi, Borislav Petkov, Tony Luck,
	Andy Lutomirski, Michael S. Tsirkin, Ricardo Neri, Matt Fleming,
	Ard Biesheuvel, Ravi Shankar

From: Sai Praneeth <sai.praneeth.prakhya@intel.com>

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 <sai.praneeth.prakhya@intel.com>
Cc: Lee, Chun-Yi <jlee@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
---
 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 <linux/sched/mm.h>
+#include <linux/sched/task.h>
+
 #include <asm/fpu/api.h>
 #include <asm/pgtable.h>
 #include <asm/processor-flags.h>
 #include <asm/tlb.h>
+#include <asm/mmu_context.h>
 
 /*
  * 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 6a151ce70e86..ccf5239923e8 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -227,6 +227,9 @@ int __init efi_alloc_page_tables(void)
 		return -ENOMEM;
 	}
 
+	mm_init_cpumask(&efi_mm);
+	init_new_context(NULL, &efi_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 <asm/ptdump.h>
 
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[] = {
 	&efi.mem_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 d813f7b04da7..6745f4dbbcc1 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -928,6 +928,8 @@ 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

^ permalink raw reply	[flat|nested] 2+ messages in thread
* [PATCH 0/3] Use mm_struct and switch_mm() instead of manually
@ 2017-08-15 19:18 Sai Praneeth Prakhya
  2017-08-15 19:18 ` [PATCH 1/3] efi: Use efi_mm in x86 as well as ARM Sai Praneeth Prakhya
  0 siblings, 1 reply; 2+ messages in thread
From: Sai Praneeth Prakhya @ 2017-08-15 19:18 UTC (permalink / raw)
  To: linux-efi, linux-kernel
  Cc: jlee, bp, luto, mst, ricardo.neri, matt, ard.biesheuvel,
	ravi.v.shankar, Sai Praneeth

From: Sai Praneeth <sai.praneeth.prakhya@intel.com>

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, so we can use a 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, 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.

Special thanks to Matt for his initial review.

Matt,
I have implemented efi_switch_mm() in "arch/x86/platform/efi/efi_64.c"
because it's used only by x86_64. Please let me know if you think it
should be in "drivers/firmware/efi/efi.c"

Andy and Michael,
As I am twiddling with memory management for the first time and I think
you are mm experts, could you please review efi_switch_mm() function
in "x86/efi: Use efi_switch_mm() rather than manually twiddling with cr3"

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           | 30 +++++++++----------
 arch/x86/platform/efi/efi_64.c       | 57 ++++++++++++++++++++++--------------
 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, 62 insertions(+), 47 deletions(-)

-- 
2.1.4

^ permalink raw reply	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-12-17  0:11 UTC | newest]

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2017-12-17  0:06 [PATCH 1/3] efi: Use efi_mm in x86 as well as ARM Sai Praneeth Prakhya
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