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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-01-04 19:09:43 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-02-17 23:27:32 +0000
commitdc21af99fadcfa0ae65b52fd0895f85824f0c288 (patch)
treed2d293d79fdb405f25ca7fb18aa16aba6ecea261 /arch/arm/include/asm/module.h
parent5b7de4547b388d3949620e21d072e35b6f2638fa (diff)
downloadblackbird-op-linux-dc21af99fadcfa0ae65b52fd0895f85824f0c288.tar.gz
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ARM: P2V: introduce phys_to_virt/virt_to_phys runtime patching
This idea came from Nicolas, Eric Miao produced an initial version, which was then rewritten into this. Patch the physical to virtual translations at runtime. As we modify the code, this makes it incompatible with XIP kernels, but allows us to achieve this with minimal loss of performance. As many translations are of the form: physical = virtual + (PHYS_OFFSET - PAGE_OFFSET) virtual = physical - (PHYS_OFFSET - PAGE_OFFSET) we generate an 'add' instruction for __virt_to_phys(), and a 'sub' instruction for __phys_to_virt(). We calculate at run time (PHYS_OFFSET - PAGE_OFFSET) by comparing the address prior to MMU initialization with where it should be once the MMU has been initialized, and place this constant into the above add/sub instructions. Once we have (PHYS_OFFSET - PAGE_OFFSET), we can calculate the real PHYS_OFFSET as PAGE_OFFSET is a build-time constant, and save this for the C-mode PHYS_OFFSET variable definition to use. At present, we are unable to support Realview with Sparsemem enabled as this uses a complex mapping function, and MSM as this requires a constant which will not fit in our math instruction. Add a module version magic string for this feature to prevent incompatible modules being loaded. Tested-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Nicolas Pitre <nicolas.pitre@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm/module.h')
-rw-r--r--arch/arm/include/asm/module.h15
1 files changed, 13 insertions, 2 deletions
diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index 12c8e680cbff..d072c21332ee 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -25,8 +25,19 @@ struct mod_arch_specific {
};
/*
- * Include the ARM architecture version.
+ * Add the ARM architecture version to the version magic string
*/
-#define MODULE_ARCH_VERMAGIC "ARMv" __stringify(__LINUX_ARM_ARCH__) " "
+#define MODULE_ARCH_VERMAGIC_ARMVSN "ARMv" __stringify(__LINUX_ARM_ARCH__) " "
+
+/* Add __virt_to_phys patching state as well */
+#ifdef CONFIG_ARM_PATCH_PHYS_VIRT
+#define MODULE_ARCH_VERMAGIC_P2V "p2v8 "
+#else
+#define MODULE_ARCH_VERMAGIC_P2V ""
+#endif
+
+#define MODULE_ARCH_VERMAGIC \
+ MODULE_ARCH_VERMAGIC_ARMVSN \
+ MODULE_ARCH_VERMAGIC_P2V
#endif /* _ASM_ARM_MODULE_H */
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