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authorBjorn Helgaas <bjorn.helgaas@hp.com>2006-01-08 01:04:13 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:14:02 -0800
commit80851ef2a5a404e6054211ca96ecd5ac4b06d297 (patch)
treedcacd2a475adc28c540b6012b58f1af9783778c1 /arch/ia64/kernel/efi.c
parent44ac8413901167589226abf824d994aa57e4fd28 (diff)
[PATCH] /dev/mem: validate mmap requests
Add a hook so architectures can validate /dev/mem mmap requests. This is analogous to validation we already perform in the read/write paths. The identity mapping scheme used on ia64 requires that each 16MB or 64MB granule be accessed with exactly one attribute (write-back or uncacheable). This avoids "attribute aliasing", which can cause a machine check. Sample problem scenario: - Machine supports VGA, so it has uncacheable (UC) MMIO at 640K-768K - efi_memmap_init() discards any write-back (WB) memory in the first granule - Application (e.g., "hwinfo") mmaps /dev/mem, offset 0 - hwinfo receives UC mapping (the default, since memmap says "no WB here") - Machine check abort (on chipsets that don't support UC access to WB memory, e.g., sx1000) In the scenario above, the only choices are - Use WB for hwinfo mmap. Can't do this because it causes attribute aliasing with the UC mapping for the VGA MMIO space. - Use UC for hwinfo mmap. Can't do this because the chipset may not support UC for that region. - Disallow the hwinfo mmap with -EINVAL. That's what this patch does. Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/ia64/kernel/efi.c')
-rw-r--r--arch/ia64/kernel/efi.c160
1 files changed, 111 insertions, 49 deletions
diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index a3aa45cbcfa..c485a3b32ba 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -247,6 +247,32 @@ typedef struct kern_memdesc {
static kern_memdesc_t *kern_memmap;
+#define efi_md_size(md) (md->num_pages << EFI_PAGE_SHIFT)
+
+static inline u64
+kmd_end(kern_memdesc_t *kmd)
+{
+ return (kmd->start + (kmd->num_pages << EFI_PAGE_SHIFT));
+}
+
+static inline u64
+efi_md_end(efi_memory_desc_t *md)
+{
+ return (md->phys_addr + efi_md_size(md));
+}
+
+static inline int
+efi_wb(efi_memory_desc_t *md)
+{
+ return (md->attribute & EFI_MEMORY_WB);
+}
+
+static inline int
+efi_uc(efi_memory_desc_t *md)
+{
+ return (md->attribute & EFI_MEMORY_UC);
+}
+
static void
walk (efi_freemem_callback_t callback, void *arg, u64 attr)
{
@@ -595,8 +621,8 @@ efi_get_iobase (void)
return 0;
}
-u32
-efi_mem_type (unsigned long phys_addr)
+static efi_memory_desc_t *
+efi_memory_descriptor (unsigned long phys_addr)
{
void *efi_map_start, *efi_map_end, *p;
efi_memory_desc_t *md;
@@ -610,13 +636,13 @@ efi_mem_type (unsigned long phys_addr)
md = p;
if (phys_addr - md->phys_addr < (md->num_pages << EFI_PAGE_SHIFT))
- return md->type;
+ return md;
}
return 0;
}
-u64
-efi_mem_attributes (unsigned long phys_addr)
+static int
+efi_memmap_has_mmio (void)
{
void *efi_map_start, *efi_map_end, *p;
efi_memory_desc_t *md;
@@ -629,36 +655,98 @@ efi_mem_attributes (unsigned long phys_addr)
for (p = efi_map_start; p < efi_map_end; p += efi_desc_size) {
md = p;
- if (phys_addr - md->phys_addr < (md->num_pages << EFI_PAGE_SHIFT))
- return md->attribute;
+ if (md->type == EFI_MEMORY_MAPPED_IO)
+ return 1;
}
return 0;
}
+
+u32
+efi_mem_type (unsigned long phys_addr)
+{
+ efi_memory_desc_t *md = efi_memory_descriptor(phys_addr);
+
+ if (md)
+ return md->type;
+ return 0;
+}
+
+u64
+efi_mem_attributes (unsigned long phys_addr)
+{
+ efi_memory_desc_t *md = efi_memory_descriptor(phys_addr);
+
+ if (md)
+ return md->attribute;
+ return 0;
+}
EXPORT_SYMBOL(efi_mem_attributes);
+/*
+ * Determines whether the memory at phys_addr supports the desired
+ * attribute (WB, UC, etc). If this returns 1, the caller can safely
+ * access *size bytes at phys_addr with the specified attribute.
+ */
+static int
+efi_mem_attribute_range (unsigned long phys_addr, unsigned long *size, u64 attr)
+{
+ efi_memory_desc_t *md = efi_memory_descriptor(phys_addr);
+ unsigned long md_end;
+
+ if (!md || (md->attribute & attr) != attr)
+ return 0;
+
+ do {
+ md_end = efi_md_end(md);
+ if (phys_addr + *size <= md_end)
+ return 1;
+
+ md = efi_memory_descriptor(md_end);
+ if (!md || (md->attribute & attr) != attr) {
+ *size = md_end - phys_addr;
+ return 1;
+ }
+ } while (md);
+ return 0;
+}
+
+/*
+ * For /dev/mem, we only allow read & write system calls to access
+ * write-back memory, because read & write don't allow the user to
+ * control access size.
+ */
int
valid_phys_addr_range (unsigned long phys_addr, unsigned long *size)
{
- void *efi_map_start, *efi_map_end, *p;
- efi_memory_desc_t *md;
- u64 efi_desc_size;
+ return efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_WB);
+}
- efi_map_start = __va(ia64_boot_param->efi_memmap);
- efi_map_end = efi_map_start + ia64_boot_param->efi_memmap_size;
- efi_desc_size = ia64_boot_param->efi_memdesc_size;
+/*
+ * We allow mmap of anything in the EFI memory map that supports
+ * either write-back or uncacheable access. For uncacheable regions,
+ * the supported access sizes are system-dependent, and the user is
+ * responsible for using the correct size.
+ *
+ * Note that this doesn't currently allow access to hot-added memory,
+ * because that doesn't appear in the boot-time EFI memory map.
+ */
+int
+valid_mmap_phys_addr_range (unsigned long phys_addr, unsigned long *size)
+{
+ if (efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_WB))
+ return 1;
- for (p = efi_map_start; p < efi_map_end; p += efi_desc_size) {
- md = p;
+ if (efi_mem_attribute_range(phys_addr, size, EFI_MEMORY_UC))
+ return 1;
- if (phys_addr - md->phys_addr < (md->num_pages << EFI_PAGE_SHIFT)) {
- if (!(md->attribute & EFI_MEMORY_WB))
- return 0;
+ /*
+ * Some firmware doesn't report MMIO regions in the EFI memory map.
+ * The Intel BigSur (a.k.a. HP i2000) has this problem. In this
+ * case, we can't use the EFI memory map to validate mmap requests.
+ */
+ if (!efi_memmap_has_mmio())
+ return 1;
- if (*size > md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - phys_addr)
- *size = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - phys_addr;
- return 1;
- }
- }
return 0;
}
@@ -707,32 +795,6 @@ efi_uart_console_only(void)
return 0;
}
-#define efi_md_size(md) (md->num_pages << EFI_PAGE_SHIFT)
-
-static inline u64
-kmd_end(kern_memdesc_t *kmd)
-{
- return (kmd->start + (kmd->num_pages << EFI_PAGE_SHIFT));
-}
-
-static inline u64
-efi_md_end(efi_memory_desc_t *md)
-{
- return (md->phys_addr + efi_md_size(md));
-}
-
-static inline int
-efi_wb(efi_memory_desc_t *md)
-{
- return (md->attribute & EFI_MEMORY_WB);
-}
-
-static inline int
-efi_uc(efi_memory_desc_t *md)
-{
- return (md->attribute & EFI_MEMORY_UC);
-}
-
/*
* Look for the first granule aligned memory descriptor memory
* that is big enough to hold EFI memory map. Make sure this