This applies on top of the patches posted by Michael today Enable livepatching. This takes patch 6/8 and 7/8 of v8 as the base. Removes the extra strict check in gcc-profile-kernel-notrace.sh and adds logic for checking offsets in livepatch. The patch for HAVE_C_RECORDMCOUNT is not required and not used here.
Depending on whether or not a TOC is generated, the offset for _mcount can be +16 or +8. The changes are such that the offset checks are specific to powerpc. Comments? Testing? I tested the sample in the livepatch directory References 1. https://patchwork.ozlabs.org/patch/581521/ 2. https://patchwork.ozlabs.org/patch/587464/ Signed-off-by: Torsten Duwe <d...@suse.de> Signed-off-by: Balbir Singh <bsinghar...@gmail.com> --- arch/powerpc/Kconfig | 3 ++ arch/powerpc/gcc-mprofile-kernel-notrace.sh | 7 ---- arch/powerpc/include/asm/livepatch.h | 61 +++++++++++++++++++++++++++++ arch/powerpc/kernel/Makefile | 1 + arch/powerpc/kernel/entry_64.S | 46 ++++++++++++++++++++++ arch/powerpc/kernel/livepatch.c | 38 ++++++++++++++++++ include/linux/livepatch.h | 13 ++++++ kernel/livepatch/core.c | 4 +- 8 files changed, 164 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 9f72565..72e46b0 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -160,6 +160,7 @@ config PPC select ARCH_HAS_DEVMEM_IS_ALLOWED select HAVE_ARCH_SECCOMP_FILTER select ARCH_HAS_UBSAN_SANITIZE_ALL + select HAVE_LIVEPATCH if PPC64 && CPU_LITTLE_ENDIAN config GENERIC_CSUM def_bool CPU_LITTLE_ENDIAN @@ -1093,3 +1094,5 @@ config PPC_LIB_RHEAP bool source "arch/powerpc/kvm/Kconfig" + +source "kernel/livepatch/Kconfig" diff --git a/arch/powerpc/gcc-mprofile-kernel-notrace.sh b/arch/powerpc/gcc-mprofile-kernel-notrace.sh index 68d6482..6dafff6 100755 --- a/arch/powerpc/gcc-mprofile-kernel-notrace.sh +++ b/arch/powerpc/gcc-mprofile-kernel-notrace.sh @@ -12,12 +12,6 @@ echo "int func() { return 0; }" | \ trace_result=$? -echo "int func() { return 0; }" | \ - $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \ - sed -n -e '/func:/,/bl _mcount/p' | grep -q TOC - -leaf_toc_result=$? - /bin/echo -e "#include <linux/compiler.h>\nnotrace int func() { return 0; }" | \ $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \ grep -q "mcount" @@ -25,7 +19,6 @@ leaf_toc_result=$? notrace_result=$? if [ "$trace_result" -eq "0" -a \ - "$leaf_toc_result" -eq "0" -a \ "$notrace_result" -eq "1" ]; then echo y else diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h new file mode 100644 index 0000000..6abb69c --- /dev/null +++ b/arch/powerpc/include/asm/livepatch.h @@ -0,0 +1,61 @@ +/* + * livepatch.h - powerpc-specific Kernel Live Patching Core + * + * Copyright (C) 2015 SUSE + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ +#ifndef _ASM_POWERPC64_LIVEPATCH_H +#define _ASM_POWERPC64_LIVEPATCH_H + +#include <linux/module.h> +#include <linux/ftrace.h> + +#ifdef CONFIG_LIVEPATCH +static inline int klp_check_compiler_support(void) +{ +#if !defined(_CALL_ELF) || _CALL_ELF != 2 || !defined(CC_USING_MPROFILE_KERNEL) + return 1; +#endif + return 0; +} + +#define ARCH_HAVE_KLP_MATCHADDR +static inline int klp_matchaddr(struct ftrace_ops *ops, unsigned long ip, + int remove, int reset) +{ + int offsets[] = {8, 16}; + int i; + int ret = 1; + + for (i = 0; i < ARRAY_SIZE(offsets); i++) { + ret = ftrace_set_filter_ip(ops, ip+offsets[i], remove, reset); + if (!ret) + break; + } + return ret; +} + +extern int klp_write_module_reloc(struct module *mod, unsigned long type, + unsigned long loc, unsigned long value); + +static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip) +{ + regs->nip = ip; +} +#else +#error Live patching support is disabled; check CONFIG_LIVEPATCH +#endif + +#endif /* _ASM_POWERPC64_LIVEPATCH_H */ diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 44667fd..405efce 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -119,6 +119,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o obj-$(CONFIG_TRACING) += trace_clock.o +obj-$(CONFIG_LIVEPATCH) += livepatch.o ifneq ($(CONFIG_PPC_INDIRECT_PIO),y) obj-y += iomap.o diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index f347f50..853717f 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1225,6 +1225,9 @@ _GLOBAL(ftrace_caller) /* Calculate ip from nip-4 into r3 for call below */ subi r3, r7, MCOUNT_INSN_SIZE +#ifdef CONFIG_LIVEPATCH + mr r14,r3 /* remember old NIP */ +#endif /* Put the original return address in r4 as parent_ip */ mr r4, r0 @@ -1247,6 +1250,9 @@ ftrace_call: /* Load ctr with the possibly modified NIP */ ld r3, _NIP(r1) mtctr r3 +#ifdef CONFIG_LIVEPATCH + cmpd r14,r3 /* has NIP been altered? */ +#endif /* Restore gprs */ REST_8GPRS(0,r1) @@ -1264,6 +1270,27 @@ ftrace_call: ld r0, LRSAVE(r1) mtlr r0 +#ifdef CONFIG_LIVEPATCH + beq+ 4f /* likely(old_NIP == new_NIP) */ + + /* For a local call, restore this TOC after calling the patch function. + * For a global call, it does not matter what we restore here, + * since the global caller does its own restore right afterwards, + * anyway. Just insert a KLP_return_helper frame in any case, + * so a patch function can always count on the changed stack offsets. + */ + stdu r1,-32(r1) /* open new mini stack frame */ + std r0,24(r1) /* save TOC now, unconditionally. */ + bl 5f +5: mflr r12 + addi r12,r12,(KLP_return_helper+4-.)@l + std r12,LRSAVE(r1) + mtlr r12 + mfctr r12 /* allow for TOC calculation in newfunc */ + bctr +4: +#endif + #ifdef CONFIG_FUNCTION_GRAPH_TRACER stdu r1, -112(r1) .globl ftrace_graph_call @@ -1279,6 +1306,25 @@ _GLOBAL(ftrace_graph_stub) #endif /* CC_USING_MPROFILE_KERNEL */ _GLOBAL(ftrace_stub) blr +#ifdef CONFIG_LIVEPATCH +/* Helper function for local calls that are becoming global + due to live patching. + We can't simply patch the NOP after the original call, + because, depending on the consistency model, some kernel + threads may still have called the original, local function + *without* saving their TOC in the respective stack frame slot, + so the decision is made per-thread during function return by + maybe inserting a KLP_return_helper frame or not. +*/ +KLP_return_helper: + ld r2,24(r1) /* restore TOC (saved by ftrace_caller) */ + addi r1, r1, 32 /* destroy mini stack frame */ + ld r0,LRSAVE(r1) /* get the real return address */ + mtlr r0 + blr +#endif + + #else _GLOBAL_TOC(_mcount) /* Taken from output of objdump from lib64/glibc */ diff --git a/arch/powerpc/kernel/livepatch.c b/arch/powerpc/kernel/livepatch.c new file mode 100644 index 0000000..cdd15f1 --- /dev/null +++ b/arch/powerpc/kernel/livepatch.c @@ -0,0 +1,38 @@ +/* + * livepatch.c - powerpc-specific Kernel Live Patching Core + * + * Copyright (C) 2015 SUSE + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ +#include <linux/module.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) +{ + /* This requires infrastructure changes; we need the loadinfos. */ + pr_err("klp_write_module_reloc not yet supported\n"); + return -ENOSYS; +} diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h index a882865..e63a5b3 100644 --- a/include/linux/livepatch.h +++ b/include/linux/livepatch.h @@ -134,6 +134,19 @@ int klp_unregister_patch(struct klp_patch *); int klp_enable_patch(struct klp_patch *); int klp_disable_patch(struct klp_patch *); +#ifndef ARCH_HAVE_KLP_MATCHADDR +static inline int klp_matchaddr(struct ftrace_ops *ops, unsigned long ip, + int remove, int reset) +{ + return ftrace_set_filter_ip(ops, ip, remove, reset); +} + +#else +int klp_matchaddr(struct ftrace_ops *ops, unsigned long ip, + int remove, int reset); + +#endif + #endif /* CONFIG_LIVEPATCH */ #endif /* _LINUX_LIVEPATCH_H_ */ diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index bc2c85c..6625b06 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -313,7 +313,7 @@ static void klp_disable_func(struct klp_func *func) if (list_is_singular(&ops->func_stack)) { WARN_ON(unregister_ftrace_function(&ops->fops)); - WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); + WARN_ON(klp_matchaddr(&ops->fops, func->old_addr, 1, 0)); list_del_rcu(&func->stack_node); list_del(&ops->node); @@ -352,7 +352,7 @@ static int klp_enable_func(struct klp_func *func) INIT_LIST_HEAD(&ops->func_stack); list_add_rcu(&func->stack_node, &ops->func_stack); - ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 0, 0); + ret = klp_matchaddr(&ops->fops, func->old_addr, 0, 0); if (ret) { pr_err("failed to set ftrace filter for function '%s' (%d)\n", func->old_name, ret); _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
