[PATCH] arm64/efi: move virtmap init to early initcall

[PATCH] arm64/efi: move virtmap init to early initcall

[Ard Biesheuvel]

Now that the create_mapping() code in mm/mmu.c is able to support
setting up kernel page tables at initcall time, we can move the whole
virtmap creation to arm64_enable_runtime_services() instead of having
a distinct stage during early boot. This also allows us to drop the
arm64-specific EFI_VIRTMAP flag.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

This applies on top of Laura's "arm64: add better page protections to arm64":
the refactoring of mmu.c she did there allows us to greatly simplify the UEFI
virtmap code, and drop the explicit 'efi_virtmap_init()' call from setup_arch().

 arch/arm64/include/asm/efi.h |  18 ++-----
 arch/arm64/kernel/efi.c      | 111 +++++++++++++++++++++----------------------
 arch/arm64/kernel/setup.c    |   1 -
 arch/arm64/mm/mmu.c          |   2 +-
 4 files changed, 59 insertions(+), 73 deletions(-)

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 7baf2cc04e1e..ef572206f1c3 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -6,10 +6,8 @@
 
 #ifdef CONFIG_EFI
 extern void efi_init(void);
-extern void efi_virtmap_init(void);
 #else
 #define efi_init()
-#define efi_virtmap_init()
 #endif
 
 #define efi_call_virt(f, ...)						\
@@ -53,23 +51,17 @@ extern void efi_virtmap_init(void);
 #define EFI_ALLOC_ALIGN		SZ_64K
 
 /*
- * On ARM systems, virtually remapped UEFI runtime services are set up in three
+ * On ARM systems, virtually remapped UEFI runtime services are set up in two
  * distinct stages:
  * - The stub retrieves the final version of the memory map from UEFI, populates
  *   the virt_addr fields and calls the SetVirtualAddressMap() [SVAM] runtime
  *   service to communicate the new mapping to the firmware (Note that the new
  *   mapping is not live at this time)
- * - During early boot, the page tables are allocated and populated based on the
- *   virt_addr fields in the memory map, but only if all descriptors with the
- *   EFI_MEMORY_RUNTIME attribute have a non-zero value for virt_addr. If this
- *   succeeds, the EFI_VIRTMAP flag is set to indicate that the virtual mappings
- *   have been installed successfully.
- * - During an early initcall(), the UEFI Runtime Services are enabled and the
- *   EFI_RUNTIME_SERVICES bit set if some conditions are met, i.e., we need a
- *   non-early mapping of the UEFI system table, and we need to have the virtmap
- *   installed.
+ * - During an early initcall(), the EFI system table is permanently remapped
+ *   and the virtual remapping of the UEFI Runtime Services regions is loaded
+ *   into a private set of page tables. If this all succeeds, the Runtime
+ *   Services are enabled and the EFI_RUNTIME_SERVICES bit set.
  */
-#define EFI_VIRTMAP		EFI_ARCH_1
 
 void efi_virtmap_load(void);
 void efi_virtmap_unload(void);
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index c9cb0fbe7aa4..b42c7b480e1e 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -38,6 +38,19 @@ struct efi_memory_map memmap;
 
 static u64 efi_system_table;
 
+static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;
+
+static struct mm_struct efi_mm = {
+	.mm_rb			= RB_ROOT,
+	.pgd			= efi_pgd,
+	.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),
+	INIT_MM_CONTEXT(efi_mm)
+};
+
 static int uefi_debug __initdata;
 static int __init uefi_debug_setup(char *str)
 {
@@ -213,6 +226,45 @@ void __init efi_init(void)
 		return;
 
 	reserve_regions();
+	early_memunmap(memmap.map, params.mmap_size);
+}
+
+static bool __init efi_virtmap_init(void)
+{
+	efi_memory_desc_t *md;
+
+	for_each_efi_memory_desc(&memmap, md) {
+		u64 paddr, npages, size;
+		pgprot_t prot;
+
+		if (!(md->attribute & EFI_MEMORY_RUNTIME))
+			continue;
+		if (md->virt_addr == 0)
+			return false;
+
+		paddr = md->phys_addr;
+		npages = md->num_pages;
+		memrange_efi_to_native(&paddr, &npages);
+		size = npages << PAGE_SHIFT;
+
+		pr_info("  EFI remap 0x%016llx => %p\n",
+			md->phys_addr, (void *)md->virt_addr);
+
+		/*
+		 * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
+		 * executable, everything else can be mapped with the XN bits
+		 * set.
+		 */
+		if (!is_normal_ram(md))
+			prot = __pgprot(PROT_DEVICE_nGnRE);
+		else if (md->type == EFI_RUNTIME_SERVICES_CODE)
+			prot = PAGE_KERNEL_EXEC;
+		else
+			prot = PAGE_KERNEL;
+
+		create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
+	}
+	return true;
 }
 
 /*
@@ -254,7 +306,7 @@ static int __init arm64_enable_runtime_services(void)
 	}
 	set_bit(EFI_SYSTEM_TABLES, &efi.flags);
 
-	if (!efi_enabled(EFI_VIRTMAP)) {
+	if (!efi_virtmap_init()) {
 		pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
 		return -1;
 	}
@@ -283,19 +335,6 @@ static int __init arm64_dmi_init(void)
 }
 core_initcall(arm64_dmi_init);
 
-static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;
-
-static struct mm_struct efi_mm = {
-	.mm_rb			= RB_ROOT,
-	.pgd			= efi_pgd,
-	.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),
-	INIT_MM_CONTEXT(efi_mm)
-};
-
 static void efi_set_pgd(struct mm_struct *mm)
 {
 	cpu_switch_mm(mm->pgd, mm);
@@ -315,47 +354,3 @@ void efi_virtmap_unload(void)
 	efi_set_pgd(current->active_mm);
 	preempt_enable();
 }
-
-void __init efi_virtmap_init(void)
-{
-	efi_memory_desc_t *md;
-
-	if (!efi_enabled(EFI_BOOT))
-		return;
-
-	for_each_efi_memory_desc(&memmap, md) {
-		u64 paddr, npages, size;
-		pgprot_t prot;
-
-		if (!(md->attribute & EFI_MEMORY_RUNTIME))
-			continue;
-		if (WARN(md->virt_addr == 0,
-			 "UEFI virtual mapping incomplete or missing -- no entry found for 0x%llx\n",
-			 md->phys_addr))
-			return;
-
-		paddr = md->phys_addr;
-		npages = md->num_pages;
-		memrange_efi_to_native(&paddr, &npages);
-		size = npages << PAGE_SHIFT;
-
-		pr_info("  EFI remap 0x%016llx => %p\n",
-			md->phys_addr, (void *)md->virt_addr);
-
-		/*
-		 * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
-		 * executable, everything else can be mapped with the XN bits
-		 * set.
-		 */
-		if (!is_normal_ram(md))
-			prot = __pgprot(PROT_DEVICE_nGnRE);
-		else if (md->type == EFI_RUNTIME_SERVICES_CODE)
-			prot = PAGE_KERNEL_EXEC;
-		else
-			prot = PAGE_KERNEL;
-
-		create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot);
-	}
-	set_bit(EFI_VIRTMAP, &efi.flags);
-	early_memunmap(memmap.map, memmap.map_end - memmap.map);
-}
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 207413fe08a0..bb10903887d4 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -382,7 +382,6 @@ void __init setup_arch(char **cmdline_p)
 	paging_init();
 	request_standard_resources();
 
-	efi_virtmap_init();
 	early_ioremap_reset();
 
 	unflatten_device_tree();
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 91d55b6efd8a..155cbb0a74b6 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -269,7 +269,7 @@ void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       pgprot_t prot)
 {
 	__create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot,
-				early_alloc);
+				late_alloc);
 }
 
 static void create_mapping_late(phys_addr_t phys, unsigned long virt,
-- 
1.8.3.2

[PATCH] arm64/efi: move virtmap init to early initcall

[Catalin Marinas]

On Thu, Jan 22, 2015 at 10:01:40AM +0000, Ard Biesheuvel wrote:
> Now that the create_mapping() code in mm/mmu.c is able to support
> setting up kernel page tables at initcall time, we can move the whole
> virtmap creation to arm64_enable_runtime_services() instead of having
> a distinct stage during early boot. This also allows us to drop the
> arm64-specific EFI_VIRTMAP flag.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Applied. Thanks.

-- 
Catalin

[PATCH] arm64/efi: move virtmap init to early initcall

[Ard Biesheuvel]

On 22 January 2015 at 15:59, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Thu, Jan 22, 2015 at 10:01:40AM +0000, Ard Biesheuvel wrote:
>> Now that the create_mapping() code in mm/mmu.c is able to support
>> setting up kernel page tables at initcall time, we can move the whole
>> virtmap creation to arm64_enable_runtime_services() instead of having
>> a distinct stage during early boot. This also allows us to drop the
>> arm64-specific EFI_VIRTMAP flag.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>
> Applied. Thanks.
>

Wow that was quick. I noticed that you mangled my S-o-b line though:
not something I care deeply about, just a FYI

[PATCH] arm64/efi: move virtmap init to early initcall

[Catalin Marinas]

On Thu, Jan 22, 2015 at 05:37:58PM +0000, Ard Biesheuvel wrote:
> On 22 January 2015 at 15:59, Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Thu, Jan 22, 2015 at 10:01:40AM +0000, Ard Biesheuvel wrote:
> >> Now that the create_mapping() code in mm/mmu.c is able to support
> >> setting up kernel page tables at initcall time, we can move the whole
> >> virtmap creation to arm64_enable_runtime_services() instead of having
> >> a distinct stage during early boot. This also allows us to drop the
> >> arm64-specific EFI_VIRTMAP flag.
> >>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >
> > Applied. Thanks.
> 
> Wow that was quick. I noticed that you mangled my S-o-b line though:
> not something I care deeply about, just a FYI

Interesting. I have a script to use the message-id and download the raw
message from gmane.org (as our email system doesn't like patches). For
some strange reason, it converts your email address but not Laura's (I
used exactly the same script with her patches).

-- 
Catalin