This warning is caused by efi_enter_virtual_mode mapping memory marked
as !EFI_RUNTIME_MEMORY. The reason this memory is being mapped is to
work around buggy code that stores an ACPI object called the Boot
Graphics Resource Table - BGRT in memory of type EfiBootServices*.
------------[ cut here ]------------
WARNING: at arch/x86/mm/ioremap.c:102 __ioremap_caller+0x3d3/0x440()
Modules linked in:
Pid: 0, comm: swapper Not tainted 3.9.0-rc7+ #95
Call Trace:
[<c102b6af>] warn_slowpath_common+0x5f/0x80
[<c1023fb3>] ? __ioremap_caller+0x3d3/0x440
[<c1023fb3>] ? __ioremap_caller+0x3d3/0x440
[<c102b6ed>] warn_slowpath_null+0x1d/0x20
[<c1023fb3>] __ioremap_caller+0x3d3/0x440
[<c106007b>] ? get_usage_chars+0xfb/0x110
[<c102d937>] ? vprintk_emit+0x147/0x480
[<c1418593>] ? efi_enter_virtual_mode+0x1e4/0x3de
[<c102406a>] ioremap_cache+0x1a/0x20
[<c1418593>] ? efi_enter_virtual_mode+0x1e4/0x3de
[<c1418593>] efi_enter_virtual_mode+0x1e4/0x3de
[<c1407984>] start_kernel+0x286/0x2f4
[<c1407535>] ? repair_env_string+0x51/0x51
[<c1407362>] i386_start_kernel+0x12c/0x12f
---[ end trace 4eaa2a86a8e2da22 ]---
On systems that do not have a BGRT object, there's no reason to map this
memory in efi_enter_virtual_mode. This patch searches for the BGRT
object and if found - will continue to map the boot services memory,
else only memory with attribute EFI_RUNTIME_MEMORY will be mapped.
Mapping only memory EFI_RUNTIME_MEMORY is is consistent with the code in
arch/ia64/kernel/efi.c:efi_enter_virtual_mode();
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue.lkml@xxxxxxxxxxxxxxxxx>
---
arch/x86/platform/efi/efi-bgrt.c | 20 +++++++++++++++-----
arch/x86/platform/efi/efi.c | 12 +++++++++---
include/linux/efi-bgrt.h | 2 ++
3 files changed, 26 insertions(+), 8 deletions(-)
diff --git a/arch/x86/platform/efi/efi-bgrt.c b/arch/x86/platform/efi/efi-bgrt.c
index 7145ec6..3655d62 100644
--- a/arch/x86/platform/efi/efi-bgrt.c
+++ b/arch/x86/platform/efi/efi-bgrt.c
@@ -25,19 +25,29 @@ struct bmp_header {
u32 size;
} __packed;
-void __init efi_bgrt_init(void)
+bool __init efi_bgrt_probe(void)
{
acpi_status status;
- void __iomem *image;
- bool ioremapped = false;
- struct bmp_header bmp_header;
if (acpi_disabled)
- return;
+ return false;
+ bgrt_tab = NULL;
status = acpi_get_table("BGRT", 0,
(struct acpi_table_header **)&bgrt_tab);
if (ACPI_FAILURE(status))
+ return false;
+
+ return true;
+}
+
+void __init efi_bgrt_init(void)
+{
+ void __iomem *image;
+ bool ioremapped = false;
+ struct bmp_header bmp_header;
+
+ if (acpi_disabled || bgrt_tab == NULL)
return;
if (bgrt_tab->header.length < sizeof(*bgrt_tab))
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 5f2ecaf..7c64a2f 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -842,6 +842,7 @@ void __init efi_enter_virtual_mode(void)
u64 end, systab, start_pfn, end_pfn;
void *p, *va, *new_memmap = NULL;
int count = 0;
+ bool bgrt_map;
efi.systab = NULL;
@@ -855,6 +856,11 @@ void __init efi_enter_virtual_mode(void)
return;
}
+ /*
+ * Determine if mapping EFI boot code/data is required for BGRT mapping
+ */
+ bgrt_map = efi_bgrt_probe();
+
/* Merge contiguous regions of the same type and attribute */
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
u64 prev_size;
@@ -884,9 +890,9 @@ void __init efi_enter_virtual_mode(void)
for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
md = p;
- if (!(md->attribute & EFI_MEMORY_RUNTIME) &&
- md->type != EFI_BOOT_SERVICES_CODE &&
- md->type != EFI_BOOT_SERVICES_DATA)
+ if (!((md->attribute & EFI_MEMORY_RUNTIME) || (bgrt_map &&
+ (md->type == EFI_BOOT_SERVICES_CODE ||
+ md->type == EFI_BOOT_SERVICES_DATA))))
continue;
size = md->num_pages << EFI_PAGE_SHIFT;
diff --git a/include/linux/efi-bgrt.h b/include/linux/efi-bgrt.h
index 051b21f..165426b 100644
--- a/include/linux/efi-bgrt.h
+++ b/include/linux/efi-bgrt.h
@@ -6,6 +6,7 @@
#include <linux/acpi.h>
void efi_bgrt_init(void);
+bool efi_bgrt_probe(void);
/* The BGRT data itself; only valid if bgrt_image != NULL. */
extern void *bgrt_image;
@@ -15,6 +16,7 @@ extern struct acpi_table_bgrt *bgrt_tab;
#else /* !CONFIG_ACPI_BGRT */
static inline void efi_bgrt_init(void) {}
+static inline bool efi_bgrt_probe(void) { return false; }
#endif /* !CONFIG_ACPI_BGRT */
--
1.7.10.4
--
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