[PATCH v2] efi/arm64: handle missing virtual mapping for UEFI System Table
If we cannot resolve the virtual address of the UEFI System Table, its physical
offset must be missing from the virtual memory map, and there is really no point
in proceeding with installing the virtual memory map and the runtime services
dispatch table. So back out gracefully.
Signed-off-by: Ard Biesheuvel ard.biesheu...@linaro.org
---
v2:
- release mappings and free virtmap before bailing
arch/arm64/kernel/efi.c | 28 ++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 56c3327bbf79..23942158e0f8 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void)
continue;
if (remap_region(md, virt_md))
++count;
+ else
+ goto err_unmap;
}
efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table);
- if (efi.systab)
- set_bit(EFI_SYSTEM_TABLES, efi.flags);
+ if (!efi.systab) {
+ /*
+* If we have no virtual mapping for the System Table at this
+* point, the memory map doesn't cover the physical offset where
+* it resides. This means the System Table will be inaccessible
+* to Runtime Services themselves once the virtual mapping is
+* installed.
+*/
+ pr_err(Failed to remap EFI System Table -- buggy firmware?\n);
+ goto err_unmap;
+ }
+ set_bit(EFI_SYSTEM_TABLES, efi.flags);
local_irq_save(flags);
cpu_switch_mm(idmap_pg_dir, init_mm);
@@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void)
set_bit(EFI_RUNTIME_SERVICES, efi.flags);
return 0;
+
+err_unmap:
+ /* unmap all mappings that succeeded: there are 'count' of those */
+ for_each_efi_memory_desc(memmap, md) {
+ if (!(md-attribute EFI_MEMORY_RUNTIME))
+ continue;
+ if (!count--)
+ break;
+ iounmap((__force void *)md-virt_addr);
+ }
+ kfree(virtmap);
+ return -1;
}
early_initcall(arm64_enter_virtual_mode);
--
1.8.3.2
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Re: [PATCH v2] efi/arm64: handle missing virtual mapping for UEFI System Table
On Fri, 2014-07-04 at 12:16 +0200, Ard Biesheuvel wrote:
If we cannot resolve the virtual address of the UEFI System Table, its
physical
offset must be missing from the virtual memory map, and there is really no
point
in proceeding with installing the virtual memory map and the runtime services
dispatch table. So back out gracefully.
Signed-off-by: Ard Biesheuvel ard.biesheu...@linaro.org
---
v2:
- release mappings and free virtmap before bailing
arch/arm64/kernel/efi.c | 28 ++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 56c3327bbf79..23942158e0f8 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void)
continue;
if (remap_region(md, virt_md))
++count;
+ else
+ goto err_unmap;
How about:
if (!remap_region(md, virt_md))
goto err_unmap;
++count;
}
efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table);
- if (efi.systab)
- set_bit(EFI_SYSTEM_TABLES, efi.flags);
+ if (!efi.systab) {
+ /*
+ * If we have no virtual mapping for the System Table at this
+ * point, the memory map doesn't cover the physical offset where
+ * it resides. This means the System Table will be inaccessible
+ * to Runtime Services themselves once the virtual mapping is
+ * installed.
+ */
+ pr_err(Failed to remap EFI System Table -- buggy firmware?\n);
+ goto err_unmap;
+ }
+ set_bit(EFI_SYSTEM_TABLES, efi.flags);
local_irq_save(flags);
cpu_switch_mm(idmap_pg_dir, init_mm);
@@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void)
set_bit(EFI_RUNTIME_SERVICES, efi.flags);
return 0;
+
+err_unmap:
+ /* unmap all mappings that succeeded: there are 'count' of those */
+ for_each_efi_memory_desc(memmap, md) {
+ if (!(md-attribute EFI_MEMORY_RUNTIME))
+ continue;
+ if (!count--)
+ break;
+ iounmap((__force void *)md-virt_addr);
+ }
This is wrong. memmap still belongs to UEFI and hasn't been touched. The
new mappings are in virtmap. So, it is even simpler:
/* unmap all mappings that succeeded: there are 'count' of those */
for (virt_md = virtmap; count; virt_md++, count--)
iounmap((__force void __iomem *)virt_md-virt_addr);
+ kfree(virtmap);
+ return -1;
}
early_initcall(arm64_enter_virtual_mode);
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Re: [PATCH v2] efi/arm64: handle missing virtual mapping for UEFI System Table
(adding Catalin)
On 4 July 2014 16:42, Mark Salter msal...@redhat.com wrote:
On Fri, 2014-07-04 at 12:16 +0200, Ard Biesheuvel wrote:
If we cannot resolve the virtual address of the UEFI System Table, its
physical
offset must be missing from the virtual memory map, and there is really no
point
in proceeding with installing the virtual memory map and the runtime services
dispatch table. So back out gracefully.
Signed-off-by: Ard Biesheuvel ard.biesheu...@linaro.org
---
v2:
- release mappings and free virtmap before bailing
arch/arm64/kernel/efi.c | 28 ++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 56c3327bbf79..23942158e0f8 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -416,11 +416,23 @@ static int __init arm64_enter_virtual_mode(void)
continue;
if (remap_region(md, virt_md))
++count;
+ else
+ goto err_unmap;
How about:
if (!remap_region(md, virt_md))
goto err_unmap;
++count;
Sure.
}
efi.systab = (__force void *)efi_lookup_mapped_addr(efi_system_table);
- if (efi.systab)
- set_bit(EFI_SYSTEM_TABLES, efi.flags);
+ if (!efi.systab) {
+ /*
+ * If we have no virtual mapping for the System Table at this
+ * point, the memory map doesn't cover the physical offset
where
+ * it resides. This means the System Table will be inaccessible
+ * to Runtime Services themselves once the virtual mapping is
+ * installed.
+ */
+ pr_err(Failed to remap EFI System Table -- buggy
firmware?\n);
+ goto err_unmap;
+ }
+ set_bit(EFI_SYSTEM_TABLES, efi.flags);
local_irq_save(flags);
cpu_switch_mm(idmap_pg_dir, init_mm);
@@ -453,5 +465,17 @@ static int __init arm64_enter_virtual_mode(void)
set_bit(EFI_RUNTIME_SERVICES, efi.flags);
return 0;
+
+err_unmap:
+ /* unmap all mappings that succeeded: there are 'count' of those */
+ for_each_efi_memory_desc(memmap, md) {
+ if (!(md-attribute EFI_MEMORY_RUNTIME))
+ continue;
+ if (!count--)
+ break;
+ iounmap((__force void *)md-virt_addr);
+ }
This is wrong. memmap still belongs to UEFI and hasn't been touched. The
new mappings are in virtmap. So, it is even simpler:
/* unmap all mappings that succeeded: there are 'count' of those */
for (virt_md = virtmap; count; virt_md++, count--)
iounmap((__force void __iomem *)virt_md-virt_addr);
Yes, you're right. Will respin.
--
Ard.
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