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 <[email protected]> --- 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
