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Date: Fri, 24 Apr 2015 11:44:09 +0900
From: AKASHI Takahiro <takahiro.akashi@...aro.org>
To: rostedt@...dmis.org, mingo@...nel.org, jpoimboe@...hat.com,
sjenning@...hat.com, jkosina@...e.cz, vojtech@...e.cz,
catalin.marinas@....com, will.deacon@....com
Cc: broonie@...nel.org, masami.hiramatsu.pt@...achi.com,
live-patching@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linaro-kernel@...ts.linaro.org, linux-kernel@...r.kernel.org,
AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC 4/4] arm64: add livepatch support
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
---
arch/arm64/Kconfig | 3 ++
arch/arm64/include/asm/livepatch.h | 38 ++++++++++++++++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/livepatch.c | 68 ++++++++++++++++++++++++++++++++++++
4 files changed, 110 insertions(+)
create mode 100644 arch/arm64/include/asm/livepatch.h
create mode 100644 arch/arm64/kernel/livepatch.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c3678ed..d4b5bac 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -61,6 +61,7 @@ config ARM64
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_GENERIC_DMA_COHERENT
select HAVE_HW_BREAKPOINT if PERF_EVENTS
+ select HAVE_LIVEPATCH
select HAVE_MEMBLOCK
select HAVE_PATA_PLATFORM
select HAVE_PERF_EVENTS
@@ -612,6 +613,8 @@ config SETEND_EMULATION
If unsure, say Y
endif
+source "kernel/livepatch/Kconfig"
+
endmenu
menu "Boot options"
diff --git a/arch/arm64/include/asm/livepatch.h b/arch/arm64/include/asm/livepatch.h
new file mode 100644
index 0000000..590d139
--- /dev/null
+++ b/arch/arm64/include/asm/livepatch.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2015 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef __ASM_LIVEPATCH_H
+#define __ASM_LIVEPATCH_H
+
+#include <linux/module.h>
+#include <linux/ftrace.h>
+
+#ifdef CONFIG_LIVEPATCH
+static inline int klp_check_compiler_support(void)
+{
+ return 0;
+}
+extern int klp_write_module_reloc(struct module *mod, unsigned long type,
+ unsigned long loc, unsigned long value);
+
+extern unsigned long ftrace_lookup_mcount(unsigned long addr);
+
+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+ regs->regs[30] = ip;
+}
+
+static inline unsigned long klp_arch_lookup_mcount(unsigned long addr)
+{
+ return ftrace_lookup_mcount(addr);
+}
+#else
+#error Live patching support is disabled; check CONFIG_LIVEPATCH
+#endif
+
+#endif /* __ASM_LIVEPATCH_H */
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 5ee07ee..7614990 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -35,6 +35,7 @@ arm64-obj-$(CONFIG_KGDB) += kgdb.o
arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o
arm64-obj-$(CONFIG_PCI) += pci.o
arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o
+arm64-obj-$(CONFIG_LIVEPATCH) += livepatch.o
obj-y += $(arm64-obj-y) vdso/
obj-m += $(arm64-obj-m)
diff --git a/arch/arm64/kernel/livepatch.c b/arch/arm64/kernel/livepatch.c
new file mode 100644
index 0000000..abe4947
--- /dev/null
+++ b/arch/arm64/kernel/livepatch.c
@@ -0,0 +1,68 @@
+/*
+ * livepatch.c - arm64-specific Kernel Live Patching Core
+ *
+ * Copyright (C) 2015 Linaro Limited
+ * Author: AKASHI Takahiro <takahiro.akashi@...aro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <asm/cacheflush.h>
+#include <asm/elf.h>
+#include <asm/insn.h>
+#include <asm/livepatch.h>
+
+/**
+ * klp_write_module_reloc() - write a relocation in a module
+ * @mod: module in which the section to be modified is found
+ * @type: ELF relocation type (see asm/elf.h)
+ * @loc: address that the relocation should be written to
+ * @value: relocation value (sym address + addend)
+ *
+ * This function writes a relocation to the specified location for
+ * a particular module.
+ */
+int klp_write_module_reloc(struct module *mod, unsigned long type,
+ unsigned long loc, unsigned long value)
+{
+ unsigned long core = (unsigned long)mod->module_core;
+ unsigned long core_ro_size = mod->core_ro_size;
+ unsigned long core_size = mod->core_size;
+ bool readonly;
+ u32 new;
+ int ret;
+
+ switch (type) {
+ case R_AARCH64_NONE:
+ return 0;
+ case R_AARCH64_CALL26:
+ break;
+ default:
+ /* unsupported relocation type */
+ return -EINVAL;
+ }
+
+ if (loc < core || loc >= core + core_size)
+ /* loc does not point to any symbol inside the module */
+ return -EINVAL;
+
+ if (loc < core + core_ro_size)
+ readonly = true;
+ else
+ readonly = false;
+
+ if (readonly)
+ set_memory_rw(loc & PAGE_MASK, 1);
+
+ new = aarch64_insn_gen_branch_imm(loc, value,
+ AARCH64_INSN_BRANCH_NOLINK);
+ ret = aarch64_insn_patch_text_nosync((void *)loc, new);
+
+ if (readonly)
+ set_memory_ro(loc & PAGE_MASK, 1);
+
+ return ret;
+}
--
1.7.9.5
--
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