diff options
| -rw-r--r-- | arch/powerpc/Kconfig | 3 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/livepatch.h | 62 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/thread_info.h | 4 | ||||
| -rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 4 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 97 | ||||
| -rw-r--r-- | arch/powerpc/kernel/irq.c | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/process.c | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/setup_64.c | 17 | ||||
| -rw-r--r-- | include/linux/ftrace.h | 1 | ||||
| -rw-r--r-- | kernel/livepatch/core.c | 34 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 14 |
11 files changed, 232 insertions, 13 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index fbebde0771c8..9b5c7bcc06c4 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -160,6 +160,7 @@ config PPC select HAVE_ARCH_SECCOMP_FILTER select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT + select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS config GENERIC_CSUM def_bool CPU_LITTLE_ENDIAN @@ -1107,3 +1108,5 @@ config PPC_LIB_RHEAP bool source "arch/powerpc/kvm/Kconfig" + +source "kernel/livepatch/Kconfig" diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h new file mode 100644 index 000000000000..a402f7f94896 --- /dev/null +++ b/arch/powerpc/include/asm/livepatch.h @@ -0,0 +1,62 @@ +/* + * livepatch.h - powerpc-specific Kernel Live Patching Core + * + * Copyright (C) 2015-2016, SUSE, IBM Corp. + * + * 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_POWERPC_LIVEPATCH_H +#define _ASM_POWERPC_LIVEPATCH_H + +#include <linux/module.h> +#include <linux/ftrace.h> + +#ifdef CONFIG_LIVEPATCH +static inline int klp_check_compiler_support(void) +{ + return 0; +} + +static inline 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. */ + return -ENOSYS; +} + +static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip) +{ + regs->nip = ip; +} + +#define klp_get_ftrace_location klp_get_ftrace_location +static inline unsigned long klp_get_ftrace_location(unsigned long faddr) +{ + /* + * Live patch works only with -mprofile-kernel on PPC. In this case, + * the ftrace location is always within the first 16 bytes. + */ + return ftrace_location_range(faddr, faddr + 16); +} + +static inline void klp_init_thread_info(struct thread_info *ti) +{ + /* + 1 to account for STACK_END_MAGIC */ + ti->livepatch_sp = (unsigned long *)(ti + 1) + 1; +} +#else +static void klp_init_thread_info(struct thread_info *ti) { } +#endif /* CONFIG_LIVEPATCH */ + +#endif /* _ASM_POWERPC_LIVEPATCH_H */ diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 7efee4a3240b..8febc3f66d53 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h @@ -43,7 +43,9 @@ struct thread_info { int preempt_count; /* 0 => preemptable, <0 => BUG */ unsigned long local_flags; /* private flags for thread */ - +#ifdef CONFIG_LIVEPATCH + unsigned long *livepatch_sp; +#endif /* low level flags - has atomic operations done on it */ unsigned long flags ____cacheline_aligned_in_smp; }; diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 0d0183d3180a..c9370d4e36bd 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -86,6 +86,10 @@ int main(void) DEFINE(KSP_LIMIT, offsetof(struct thread_struct, ksp_limit)); #endif /* CONFIG_PPC64 */ +#ifdef CONFIG_LIVEPATCH + DEFINE(TI_livepatch_sp, offsetof(struct thread_info, livepatch_sp)); +#endif + DEFINE(KSP, offsetof(struct thread_struct, ksp)); DEFINE(PT_REGS, offsetof(struct thread_struct, regs)); #ifdef CONFIG_BOOKE diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 9916d150b28c..39a79c89a4b6 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -20,6 +20,7 @@ #include <linux/errno.h> #include <linux/err.h> +#include <linux/magic.h> #include <asm/unistd.h> #include <asm/processor.h> #include <asm/page.h> @@ -1248,6 +1249,9 @@ _GLOBAL(ftrace_caller) addi r3,r3,function_trace_op@toc@l ld r5,0(r3) +#ifdef CONFIG_LIVEPATCH + mr r14,r7 /* remember old NIP */ +#endif /* Calculate ip from nip-4 into r3 for call below */ subi r3, r7, MCOUNT_INSN_SIZE @@ -1272,6 +1276,9 @@ 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) @@ -1289,6 +1296,11 @@ ftrace_call: ld r0, LRSAVE(r1) mtlr r0 +#ifdef CONFIG_LIVEPATCH + /* Based on the cmpd above, if the NIP was altered handle livepatch */ + bne- livepatch_handler +#endif + #ifdef CONFIG_FUNCTION_GRAPH_TRACER stdu r1, -112(r1) .globl ftrace_graph_call @@ -1305,6 +1317,91 @@ _GLOBAL(ftrace_graph_stub) _GLOBAL(ftrace_stub) blr + +#ifdef CONFIG_LIVEPATCH + /* + * This function runs in the mcount context, between two functions. As + * such it can only clobber registers which are volatile and used in + * function linkage. + * + * We get here when a function A, calls another function B, but B has + * been live patched with a new function C. + * + * On entry: + * - we have no stack frame and can not allocate one + * - LR points back to the original caller (in A) + * - CTR holds the new NIP in C + * - r0 & r12 are free + * + * r0 can't be used as the base register for a DS-form load or store, so + * we temporarily shuffle r1 (stack pointer) into r0 and then put it back. + */ +livepatch_handler: + CURRENT_THREAD_INFO(r12, r1) + + /* Save stack pointer into r0 */ + mr r0, r1 + + /* Allocate 3 x 8 bytes */ + ld r1, TI_livepatch_sp(r12) + addi r1, r1, 24 + std r1, TI_livepatch_sp(r12) + + /* Save toc & real LR on livepatch stack */ + std r2, -24(r1) + mflr r12 + std r12, -16(r1) + + /* Store stack end marker */ + lis r12, STACK_END_MAGIC@h + ori r12, r12, STACK_END_MAGIC@l + std r12, -8(r1) + + /* Restore real stack pointer */ + mr r1, r0 + + /* Put ctr in r12 for global entry and branch there */ + mfctr r12 + bctrl + + /* + * Now we are returning from the patched function to the original + * caller A. We are free to use r0 and r12, and we can use r2 until we + * restore it. + */ + + CURRENT_THREAD_INFO(r12, r1) + + /* Save stack pointer into r0 */ + mr r0, r1 + + ld r1, TI_livepatch_sp(r12) + + /* Check stack marker hasn't been trashed */ + lis r2, STACK_END_MAGIC@h + ori r2, r2, STACK_END_MAGIC@l + ld r12, -8(r1) +1: tdne r12, r2 + EMIT_BUG_ENTRY 1b, __FILE__, __LINE__ - 1, 0 + + /* Restore LR & toc from livepatch stack */ + ld r12, -16(r1) + mtlr r12 + ld r2, -24(r1) + + /* Pop livepatch stack frame */ + CURRENT_THREAD_INFO(r12, r0) + subi r1, r1, 24 + std r1, TI_livepatch_sp(r12) + + /* Restore real stack pointer */ + mr r1, r0 + + /* Return to original caller of live patched function */ + blr +#endif + + #else _GLOBAL_TOC(_mcount) /* Taken from output of objdump from lib64/glibc */ diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c index 290559df1e8b..3cb46a3b1de7 100644 --- a/arch/powerpc/kernel/irq.c +++ b/arch/powerpc/kernel/irq.c @@ -66,6 +66,7 @@ #include <asm/udbg.h> #include <asm/smp.h> #include <asm/debug.h> +#include <asm/livepatch.h> #ifdef CONFIG_PPC64 #include <asm/paca.h> @@ -607,10 +608,12 @@ void irq_ctx_init(void) memset((void *)softirq_ctx[i], 0, THREAD_SIZE); tp = softirq_ctx[i]; tp->cpu = i; + klp_init_thread_info(tp); memset((void *)hardirq_ctx[i], 0, THREAD_SIZE); tp = hardirq_ctx[i]; tp->cpu = i; + klp_init_thread_info(tp); } } diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 4695088e7dd2..ad79816f13fe 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -57,6 +57,8 @@ #endif #include <asm/code-patching.h> #include <asm/exec.h> +#include <asm/livepatch.h> + #include <linux/kprobes.h> #include <linux/kdebug.h> @@ -1402,13 +1404,15 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, extern void ret_from_kernel_thread(void); void (*f)(void); unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE; + struct thread_info *ti = task_thread_info(p); + + klp_init_thread_info(ti); /* Copy registers */ sp -= sizeof(struct pt_regs); childregs = (struct pt_regs *) sp; if (unlikely(p->flags & PF_KTHREAD)) { /* kernel thread */ - struct thread_info *ti = (void *)task_stack_page(p); memset(childregs, 0, sizeof(struct pt_regs)); childregs->gpr[1] = sp + sizeof(struct pt_regs); /* function */ diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index f98be8383a39..96d4a2b23d0f 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -69,6 +69,7 @@ #include <asm/kvm_ppc.h> #include <asm/hugetlb.h> #include <asm/epapr_hcalls.h> +#include <asm/livepatch.h> #ifdef DEBUG #define DBG(fmt...) udbg_printf(fmt) @@ -667,16 +668,16 @@ static void __init emergency_stack_init(void) limit = min(safe_stack_limit(), ppc64_rma_size); for_each_possible_cpu(i) { - unsigned long sp; - sp = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit); - sp += THREAD_SIZE; - paca[i].emergency_sp = __va(sp); + struct thread_info *ti; + ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit)); + klp_init_thread_info(ti); + paca[i].emergency_sp = (void *)ti + THREAD_SIZE; #ifdef CONFIG_PPC_BOOK3S_64 /* emergency stack for machine check exception handling. */ - sp = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit); - sp += THREAD_SIZE; - paca[i].mc_emergency_sp = __va(sp); + ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit)); + klp_init_thread_info(ti); + paca[i].mc_emergency_sp = (void *)ti + THREAD_SIZE; #endif } } @@ -700,6 +701,8 @@ void __init setup_arch(char **cmdline_p) if (ppc_md.panic) setup_panic(); + klp_init_thread_info(&init_thread_info); + init_mm.start_code = (unsigned long)_stext; init_mm.end_code = (unsigned long) _etext; init_mm.end_data = (unsigned long) _edata; diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index dea12a6e413b..66a36a815f0a 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -455,6 +455,7 @@ int ftrace_update_record(struct dyn_ftrace *rec, int enable); int ftrace_test_record(struct dyn_ftrace *rec, int enable); void ftrace_run_stop_machine(int command); unsigned long ftrace_location(unsigned long ip); +unsigned long ftrace_location_range(unsigned long start, unsigned long end); unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec); unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec); diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c index d68fbf63b083..b0476bb30f92 100644 --- a/kernel/livepatch/core.c +++ b/kernel/livepatch/core.c @@ -298,6 +298,19 @@ unlock: rcu_read_unlock(); } +/* + * Convert a function address into the appropriate ftrace location. + * + * Usually this is just the address of the function, but on some architectures + * it's more complicated so allow them to provide a custom behaviour. + */ +#ifndef klp_get_ftrace_location +static unsigned long klp_get_ftrace_location(unsigned long faddr) +{ + return faddr; +} +#endif + static void klp_disable_func(struct klp_func *func) { struct klp_ops *ops; @@ -312,8 +325,14 @@ static void klp_disable_func(struct klp_func *func) return; if (list_is_singular(&ops->func_stack)) { + unsigned long ftrace_loc; + + ftrace_loc = klp_get_ftrace_location(func->old_addr); + if (WARN_ON(!ftrace_loc)) + return; + WARN_ON(unregister_ftrace_function(&ops->fops)); - WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0)); + WARN_ON(ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0)); list_del_rcu(&func->stack_node); list_del(&ops->node); @@ -338,6 +357,15 @@ static int klp_enable_func(struct klp_func *func) ops = klp_find_ops(func->old_addr); if (!ops) { + unsigned long ftrace_loc; + + ftrace_loc = klp_get_ftrace_location(func->old_addr); + if (!ftrace_loc) { + pr_err("failed to find location for function '%s'\n", + func->old_name); + return -EINVAL; + } + ops = kzalloc(sizeof(*ops), GFP_KERNEL); if (!ops) return -ENOMEM; @@ -352,7 +380,7 @@ 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 = ftrace_set_filter_ip(&ops->fops, ftrace_loc, 0, 0); if (ret) { pr_err("failed to set ftrace filter for function '%s' (%d)\n", func->old_name, ret); @@ -363,7 +391,7 @@ static int klp_enable_func(struct klp_func *func) if (ret) { pr_err("failed to register ftrace handler for function '%s' (%d)\n", func->old_name, ret); - ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0); + ftrace_set_filter_ip(&ops->fops, ftrace_loc, 1, 0); goto err; } diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b1870fbd2b67..7e8d792da963 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1530,7 +1530,19 @@ static int ftrace_cmp_recs(const void *a, const void *b) return 0; } -static unsigned long ftrace_location_range(unsigned long start, unsigned long end) +/** + * ftrace_location_range - return the first address of a traced location + * if it touches the given ip range + * @start: start of range to search. + * @end: end of range to search (inclusive). @end points to the last byte + * to check. + * + * Returns rec->ip if the related ftrace location is a least partly within + * the given address range. That is, the first address of the instruction + * that is either a NOP or call to the function tracer. It checks the ftrace + * internal tables to determine if the address belongs or not. + */ +unsigned long ftrace_location_range(unsigned long start, unsigned long end) { struct ftrace_page *pg; struct dyn_ftrace *rec; |