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McKenney" , Christoph Hellwig , Peter Zijlstra , bpf@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Sami Tolvanen X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210323_203956_356428_3CC44B6D X-CRM114-Status: GOOD ( 13.29 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org With CONFIG_CFI_CLANG, the compiler replaces function addresses in instrumented C code with jump table addresses. This means that __pa_symbol(function) returns the physical address of the jump table entry instead of the actual function, which may not work as the jump table code will immediately jump to a virtual address that may not be mapped. To avoid this address space confusion, this change adds generic definitions for __va_function and __pa_function, which architectures that support CFI can override. The typical implementation of the __va_function macro would use inline assembly to take the function address, which avoids compiler instrumentation. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook --- include/linux/mm.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 64a71bf20536..a0d285cd59ce 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -116,6 +116,14 @@ extern int mmap_rnd_compat_bits __read_mostly; #define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0)) #endif +#ifndef __va_function +#define __va_function(x) (x) +#endif + +#ifndef __pa_function +#define __pa_function(x) __pa_symbol(__va_function(x)) +#endif + #ifndef page_to_virt #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x))) #endif