Andrew, could you replace dev-mem-validate-mmap-requests.patch
with the patch below? This addresses Tony's request that
the checking handle regions that span EFI memory descriptors.
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 <[email protected]>
arch/ia64/kernel/efi.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
drivers/char/mem.c | 14 ++++++++++++--
include/asm-ia64/io.h | 1 +
3 files changed, 57 insertions(+), 2 deletions(-)
Index: work6/arch/ia64/kernel/efi.c
===================================================================
--- work6.orig/arch/ia64/kernel/efi.c 2005-12-19 12:50:52.000000000 -0700
+++ work6/arch/ia64/kernel/efi.c 2005-12-20 10:32:49.000000000 -0700
@@ -247,6 +247,32 @@
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 @@
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 @@
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 @@
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 @@
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
Index: work6/drivers/char/mem.c
===================================================================
--- work6.orig/drivers/char/mem.c 2005-12-19 12:50:52.000000000 -0700
+++ work6/drivers/char/mem.c 2005-12-20 10:32:49.000000000 -0700
@@ -101,6 +101,11 @@
return 1;
}
+
+static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t *size)
+{
+ return 1;
+}
#endif
/*
@@ -244,15 +249,20 @@
static int mmap_mem(struct file * file, struct vm_area_struct * vma)
{
+ size_t size = vma->vm_end - vma->vm_start;
+
+ if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, &size))
+ return -EINVAL;
+
vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
- vma->vm_end - vma->vm_start,
+ size,
vma->vm_page_prot);
/* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
if (remap_pfn_range(vma,
vma->vm_start,
vma->vm_pgoff,
- vma->vm_end-vma->vm_start,
+ size,
vma->vm_page_prot))
return -EAGAIN;
return 0;
Index: work6/include/asm-ia64/io.h
===================================================================
--- work6.orig/include/asm-ia64/io.h 2005-12-19 12:50:52.000000000 -0700
+++ work6/include/asm-ia64/io.h 2005-12-20 10:32:49.000000000 -0700
@@ -89,6 +89,7 @@
#define ARCH_HAS_VALID_PHYS_ADDR_RANGE
extern int valid_phys_addr_range (unsigned long addr, size_t *count); /* efi.c */
+extern int valid_mmap_phys_addr_range (unsigned long addr, size_t *count);
/*
* The following two macros are deprecated and scheduled for removal.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
