On 11/11/2016 04:44 PM, Florian Fainelli wrote:
> When CONFIG_DEBUG_VM is turned on, virt_to_phys() maps to
> debug_virt_to_phys() which helps catch vmalloc space addresses being
> passed. This is helpful in debugging bogus drivers that just assume
> linear mappings all over the place.
>
> For ARM, ARM64, Unicore32 and Microblaze, the architectures define
> __virt_to_phys() as being the functional implementation of the address
> translation, so we special case the debug stub to call into
> __virt_to_phys directly.
>
> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> ---
> arch/arm/include/asm/memory.h | 4 ++++
> arch/arm64/include/asm/memory.h | 4 ++++
> include/asm-generic/memory_model.h | 4 ++++
> mm/debug.c | 15 +++++++++++++++
> 4 files changed, 27 insertions(+)
>
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 76cbd9c674df..448dec9b8b00 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -260,11 +260,15 @@ static inline unsigned long __phys_to_virt(phys_addr_t x)
> * translation for translating DMA addresses. Use the driver
> * DMA support - see dma-mapping.h.
> */
> +#ifndef CONFIG_DEBUG_VM
> #define virt_to_phys virt_to_phys
> static inline phys_addr_t virt_to_phys(const volatile void *x)
> {
> return __virt_to_phys((unsigned long)(x));
> }
> +#else
> +#define virt_to_phys debug_virt_to_phys
> +#endif
>
> #define phys_to_virt phys_to_virt
> static inline void *phys_to_virt(phys_addr_t x)
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index b71086d25195..c9e436b28523 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -186,11 +186,15 @@ extern u64 kimage_voffset;
> * translation for translating DMA addresses. Use the driver
> * DMA support - see dma-mapping.h.
> */
> +#ifndef CONFIG_DEBUG_VM
> #define virt_to_phys virt_to_phys
> static inline phys_addr_t virt_to_phys(const volatile void *x)
> {
> return __virt_to_phys((unsigned long)(x));
> }
> +#else
> +#define virt_to_phys debug_virt_to_phys
> +#endif
>
> #define phys_to_virt phys_to_virt
> static inline void *phys_to_virt(phys_addr_t x)
> diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
> index 5148150cc80b..426085757258 100644
> --- a/include/asm-generic/memory_model.h
> +++ b/include/asm-generic/memory_model.h
> @@ -80,6 +80,10 @@
> #define page_to_pfn __page_to_pfn
> #define pfn_to_page __pfn_to_page
>
> +#ifdef CONFIG_DEBUG_VM
> +unsigned long debug_virt_to_phys(volatile void *address);
> +#endif /* CONFIG_DEBUG_VM */
> +
> #endif /* __ASSEMBLY__ */
>
> #endif
> diff --git a/mm/debug.c b/mm/debug.c
> index 9feb699c5d25..72b2ca9b11f4 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -161,4 +161,19 @@ void dump_mm(const struct mm_struct *mm)
> );
> }
>
> +#include <asm/memory.h>
> +#include <linux/mm.h>
> +
> +unsigned long debug_virt_to_phys(volatile void *address)
> +{
> + BUG_ON(is_vmalloc_addr((const void *)address));
> +#if defined(CONFIG_ARM) || defined(CONFIG_ARM64) || defined(CONFIG_UNICORE32) || \
> + defined(CONFIG_MICROBLAZE)
> + return __virt_to_phys(address);
> +#else
> + return virt_to_phys(address);
> +#endif
> +}
> +EXPORT_SYMBOL(debug_virt_to_phys);
> +
> #endif /* CONFIG_DEBUG_VM */
>
is_vmalloc_addr is necessary but not sufficient. This misses
cases like module addresses. The x86 version (CONFIG_DEBUG_VIRTUAL)
bounds checks against the known linear map to catch all cases.
I'm for a generic approach to this if it can catch all cases
that an architecture specific version would catch.
Thanks,
Laura
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