x86 has an option CONFIG_DEBUG_VIRTUAL to do additional checks
on virt_to_phys calls. The goal is to catch users who are calling
virt_to_phys on non-linear addresses immediately. This inclues callers
using virt_to_phys on image addresses instead of __pa_symbol. As features
such as CONFIG_VMAP_STACK get enabled for arm64, this becomes increasingly
important. Add checks to catch bad virt_to_phys usage.
Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
v3: Make use of __pa_symbol required via debug checks. It's a WARN for now but
it can become a BUG after wider testing. __virt_to_phys is
now for linear addresses only. Dropped the VM_BUG_ON from Catalin's suggested
version from the nodebug version since having that in the nodebug version
essentially made them the debug version. Changed to KERNEL_START/KERNEL_END
for bounds checking. More comments.
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/memory.h | 32 ++++++++++++++++++++++++++++----
arch/arm64/mm/Makefile | 1 +
arch/arm64/mm/physaddr.c | 39 +++++++++++++++++++++++++++++++++++++++
4 files changed, 69 insertions(+), 4 deletions(-)
create mode 100644 arch/arm64/mm/physaddr.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 969ef88..83b95bc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -6,6 +6,7 @@ config ARM64
select ACPI_MCFG if ACPI
select ACPI_SPCR_TABLE if ACPI
select ARCH_CLOCKSOURCE_DATA
+ select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_ELF_RANDOMIZE
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 1e65299..2ed712e 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -167,10 +167,33 @@ extern u64 kimage_voffset;
* private definitions which should NOT be used outside memory.h
* files. Use virt_to_phys/phys_to_virt/__pa/__va instead.
*/
-#define __virt_to_phys(x) ({ \
+
+
+/*
+ * This is for translation from the standard linear map to physical addresses.
+ * It is not to be used for kernel symbols.
+ */
+#define __virt_to_phys_nodebug(x) ({ \
phys_addr_t __x = (phys_addr_t)(x); \
- __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
- (__x - kimage_voffset); })
+ ((__x & ~PAGE_OFFSET) + PHYS_OFFSET); \
+})
+
+/*
+ * This is for translation from a kernel image/symbol address to a
+ * physical address.
+ */
+#define __pa_symbol_nodebug(x) ({ \
+ phys_addr_t __x = (phys_addr_t)(x); \
+ (__x - kimage_voffset); \
+})
+
+#ifdef CONFIG_DEBUG_VIRTUAL
+extern unsigned long __virt_to_phys(unsigned long x);
+extern unsigned long __phys_addr_symbol(unsigned long x);
+#else
+#define __virt_to_phys(x) __virt_to_phys_nodebug(x)
+#define __phys_addr_symbol(x) __pa_symbol_nodebug(x)
+#endif
#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
#define __phys_to_kimg(x) ((unsigned long)((x) + kimage_voffset))
@@ -202,7 +225,8 @@ static inline void *phys_to_virt(phys_addr_t x)
* Drivers should NOT use these either.
*/
#define __pa(x) __virt_to_phys((unsigned long)(x))
-#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
+#define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
+#define __pa_nodebug(x) __virt_to_phys_nodebug((unsigned long)(x))
#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#define virt_to_pfn(x) __phys_to_pfn(__virt_to_phys((unsigned long)(x)))
diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
index 54bb209..0d37c19 100644
--- a/arch/arm64/mm/Makefile
+++ b/arch/arm64/mm/Makefile
@@ -5,6 +5,7 @@ obj-y := dma-mapping.o extable.o fault.o init.o \
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
obj-$(CONFIG_ARM64_PTDUMP) += dump.o
obj-$(CONFIG_NUMA) += numa.o
+obj-$(CONFIG_DEBUG_VIRTUAL) += physaddr.o
obj-$(CONFIG_KASAN) += kasan_init.o
KASAN_SANITIZE_kasan_init.o := n
diff --git a/arch/arm64/mm/physaddr.c b/arch/arm64/mm/physaddr.c
new file mode 100644
index 0000000..f8eb781
--- /dev/null
+++ b/arch/arm64/mm/physaddr.c
@@ -0,0 +1,39 @@
+#include <linux/mm.h>
+
+#include <asm/memory.h>
+
+unsigned long __virt_to_phys(unsigned long x)
+{
+ phys_addr_t __x = (phys_addr_t)x;
+
+ if (__x & BIT(VA_BITS - 1)) {
+ /*
+ * The linear kernel range starts in the middle of the virtual
+ * adddress space. Testing the top bit for the start of the
+ * region is a sufficient check.
+ */
+ return (__x & ~PAGE_OFFSET) + PHYS_OFFSET;
+ } else {
+ /*
+ * __virt_to_phys should not be used on symbol addresses.
+ * This should be changed to a BUG once all basic bad uses have
+ * been cleaned up.
+ */
+ WARN(1, "Do not use virt_to_phys on symbol addresses");
+ return __phys_addr_symbol(x);
+ }
+}
+EXPORT_SYMBOL(__virt_to_phys);
+
+unsigned long __phys_addr_symbol(unsigned long x)
+{
+ phys_addr_t __x = (phys_addr_t)x;
+
+ /*
+ * This is bounds checking against the kernel image only.
+ * __pa_symbol should only be used on kernel symbol addresses.
+ */
+ VIRTUAL_BUG_ON(x < (unsigned long) KERNEL_START || x > (unsigned long) KERNEL_END);
+ return (__x - kimage_voffset);
+}
+EXPORT_SYMBOL(__phys_addr_symbol);
--
2.7.4
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