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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=CeeN3xK5WAqMYQUfCf/QpaYnEzhU3e+FKSYu/FFXY8U=; b=KROj7n6gM+0M8G54BVvXBMHYwxqP4hNdyjQ+Psv7dWZ/5cNUhiyRGRFCdWZhZcD2cA I5bLrm0c2qKPFg4RRW3Pl20JhYICvcgUQpn9Ym8jotHZ8VocvqLAK/4Gdwmj3Vhr0iWR Mg0zpvItTTSv5ZRocxHYeb15iEw4sXo2+/xN27Whlk4brITIzw3BM9lsJV8vKj4a9Q8y GPmss1AT6Qc4N9wGsftWzJdWj2Np6pB1tFReMFIgpZoV+7NxvbATNK80ozC1xZUZIBee TQus4uooCJwaAxuLA7LGMB2tk7HfDttiTmotFhp9nOoYO82ln+EOdOGwnKY3BMtKLuMU rDlw== X-Gm-Message-State: AOAM532reKKNB3AuFw7KXDZH0Oc7+l28ANCFpunZhBh3QulpioX0eJW9 cX/nX78gDDecNgReQniZAis2iRpHKOFaRmRQPqw= X-Google-Smtp-Source: ABdhPJwjquHhXc1azJY3wJx2N7E06CHn55yFR9L2LbefYUmXDDh/IrCaqT99xH2KOyCrVwPGAoCRUF+Cuh4wGPAPnqw= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:c86b:8269:af92:55a]) (user=samitolvanen job=sendgmr) by 2002:a05:6214:1144:: with SMTP id b4mr10460988qvt.12.1615510166369; Thu, 11 Mar 2021 16:49:26 -0800 (PST) Date: Thu, 11 Mar 2021 16:49:05 -0800 In-Reply-To: <20210312004919.669614-1-samitolvanen@google.com> Message-Id: <20210312004919.669614-4-samitolvanen@google.com> Mime-Version: 1.0 References: <20210312004919.669614-1-samitolvanen@google.com> X-Mailer: git-send-email 2.31.0.rc2.261.g7f71774620-goog Subject: [PATCH 03/17] mm: add generic __va_function and __pa_function macros From: Sami Tolvanen To: Kees Cook Cc: Nathan Chancellor , Nick Desaulniers , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , 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-20210312_004928_294178_BE7575B9 X-CRM114-Status: GOOD ( 12.29 ) 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 77e64e3eac80..1262c4c0242c 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