diff options
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/Makefile | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 13 | ||||
| -rw-r--r-- | arch/powerpc/kernel/kprobes-ftrace.c | 104 | ||||
| -rw-r--r-- | arch/powerpc/kernel/kprobes.c | 149 | ||||
| -rw-r--r-- | arch/powerpc/kernel/optprobes.c | 6 |
5 files changed, 244 insertions, 31 deletions
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 811f441a125f..3e461637b64d 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -97,6 +97,7 @@ obj-$(CONFIG_BOOTX_TEXT) += btext.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_OPTPROBES) += optprobes.o optprobes_head.o +obj-$(CONFIG_KPROBES_ON_FTRACE) += kprobes-ftrace.o obj-$(CONFIG_UPROBES) += uprobes.o obj-$(CONFIG_PPC_UDBG_16550) += legacy_serial.o udbg_16550.o obj-$(CONFIG_STACKTRACE) += stacktrace.o @@ -150,6 +151,8 @@ GCOV_PROFILE_machine_kexec_32.o := n UBSAN_SANITIZE_machine_kexec_32.o := n GCOV_PROFILE_kprobes.o := n UBSAN_SANITIZE_kprobes.o := n +GCOV_PROFILE_kprobes-ftrace.o := n +UBSAN_SANITIZE_kprobes-ftrace.o := n UBSAN_SANITIZE_vdso.o := n extra-$(CONFIG_PPC_FPU) += fpu.o diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index cb3fb98a5785..70a5c1948b05 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1248,9 +1248,10 @@ _GLOBAL(ftrace_caller) /* Get the _mcount() call site out of LR */ mflr r7 - /* Save it as pt_regs->nip & pt_regs->link */ + /* Save it as pt_regs->nip */ std r7, _NIP(r1) - std r7, _LINK(r1) + /* Save the read LR in pt_regs->link */ + std r0, _LINK(r1) /* Save callee's TOC in the ABI compliant location */ std r2, 24(r1) @@ -1297,16 +1298,16 @@ ftrace_call: REST_8GPRS(16,r1) REST_8GPRS(24,r1) + /* Restore possibly modified LR */ + ld r0, _LINK(r1) + mtlr r0 + /* Restore callee's TOC */ ld r2, 24(r1) /* Pop our stack frame */ addi r1, r1, SWITCH_FRAME_SIZE - /* Restore original LR for return to B */ - ld r0, LRSAVE(r1) - mtlr r0 - #ifdef CONFIG_LIVEPATCH /* Based on the cmpd above, if the NIP was altered handle livepatch */ bne- livepatch_handler diff --git a/arch/powerpc/kernel/kprobes-ftrace.c b/arch/powerpc/kernel/kprobes-ftrace.c new file mode 100644 index 000000000000..6c089d9757c9 --- /dev/null +++ b/arch/powerpc/kernel/kprobes-ftrace.c @@ -0,0 +1,104 @@ +/* + * Dynamic Ftrace based Kprobes Optimization + * + * 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, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) Hitachi Ltd., 2012 + * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> + * IBM Corporation + */ +#include <linux/kprobes.h> +#include <linux/ptrace.h> +#include <linux/hardirq.h> +#include <linux/preempt.h> +#include <linux/ftrace.h> + +static nokprobe_inline +int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb, unsigned long orig_nip) +{ + /* + * Emulate singlestep (and also recover regs->nip) + * as if there is a nop + */ + regs->nip = (unsigned long)p->addr + MCOUNT_INSN_SIZE; + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + __this_cpu_write(current_kprobe, NULL); + if (orig_nip) + regs->nip = orig_nip; + return 1; +} + +int skip_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + if (kprobe_ftrace(p)) + return __skip_singlestep(p, regs, kcb, 0); + else + return 0; +} +NOKPROBE_SYMBOL(skip_singlestep); + +/* Ftrace callback handler for kprobes */ +void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, + struct ftrace_ops *ops, struct pt_regs *regs) +{ + struct kprobe *p; + struct kprobe_ctlblk *kcb; + unsigned long flags; + + /* Disable irq for emulating a breakpoint and avoiding preempt */ + local_irq_save(flags); + hard_irq_disable(); + + p = get_kprobe((kprobe_opcode_t *)nip); + if (unlikely(!p) || kprobe_disabled(p)) + goto end; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_nip = regs->nip; + + /* + * On powerpc, NIP is *before* this instruction for the + * pre handler + */ + regs->nip -= MCOUNT_INSN_SIZE; + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) + __skip_singlestep(p, regs, kcb, orig_nip); + /* + * If pre_handler returns !0, it sets regs->nip and + * resets current kprobe. + */ + } +end: + local_irq_restore(flags); +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.insn = NULL; + p->ainsn.boostable = -1; + return 0; +} diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index fa3cfd90c83a..160ae0fa7d0d 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -51,6 +51,77 @@ bool arch_within_kprobe_blacklist(unsigned long addr) addr < (unsigned long)__head_end); } +kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) +{ + kprobe_opcode_t *addr; + +#ifdef PPC64_ELF_ABI_v2 + /* PPC64 ABIv2 needs local entry point */ + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); + if (addr && !offset) { +#ifdef CONFIG_KPROBES_ON_FTRACE + unsigned long faddr; + /* + * Per livepatch.h, ftrace location is always within the first + * 16 bytes of a function on powerpc with -mprofile-kernel. + */ + faddr = ftrace_location_range((unsigned long)addr, + (unsigned long)addr + 16); + if (faddr) + addr = (kprobe_opcode_t *)faddr; + else +#endif + addr = (kprobe_opcode_t *)ppc_function_entry(addr); + } +#elif defined(PPC64_ELF_ABI_v1) + /* + * 64bit powerpc ABIv1 uses function descriptors: + * - Check for the dot variant of the symbol first. + * - If that fails, try looking up the symbol provided. + * + * This ensures we always get to the actual symbol and not + * the descriptor. + * + * Also handle <module:symbol> format. + */ + char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN]; + const char *modsym; + bool dot_appended = false; + if ((modsym = strchr(name, ':')) != NULL) { + modsym++; + if (*modsym != '\0' && *modsym != '.') { + /* Convert to <module:.symbol> */ + strncpy(dot_name, name, modsym - name); + dot_name[modsym - name] = '.'; + dot_name[modsym - name + 1] = '\0'; + strncat(dot_name, modsym, + sizeof(dot_name) - (modsym - name) - 2); + dot_appended = true; + } else { + dot_name[0] = '\0'; + strncat(dot_name, name, sizeof(dot_name) - 1); + } + } else if (name[0] != '.') { + dot_name[0] = '.'; + dot_name[1] = '\0'; + strncat(dot_name, name, KSYM_NAME_LEN - 2); + dot_appended = true; + } else { + dot_name[0] = '\0'; + strncat(dot_name, name, KSYM_NAME_LEN - 1); + } + addr = (kprobe_opcode_t *)kallsyms_lookup_name(dot_name); + if (!addr && dot_appended) { + /* Let's try the original non-dot symbol lookup */ + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); + } +#else + addr = (kprobe_opcode_t *)kallsyms_lookup_name(name); +#endif + + return addr; +} + int arch_prepare_kprobe(struct kprobe *p) { int ret = 0; @@ -144,6 +215,19 @@ static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs kcb->kprobe_saved_msr = regs->msr; } +bool arch_function_offset_within_entry(unsigned long offset) +{ +#ifdef PPC64_ELF_ABI_v2 +#ifdef CONFIG_KPROBES_ON_FTRACE + return offset <= 16; +#else + return offset <= 8; +#endif +#else + return !offset; +#endif +} + void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { ri->ret_addr = (kprobe_opcode_t *)regs->link; @@ -153,6 +237,36 @@ void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) } NOKPROBE_SYMBOL(arch_prepare_kretprobe); +int try_to_emulate(struct kprobe *p, struct pt_regs *regs) +{ + int ret; + unsigned int insn = *p->ainsn.insn; + + /* regs->nip is also adjusted if emulate_step returns 1 */ + ret = emulate_step(regs, insn); + if (ret > 0) { + /* + * Once this instruction has been boosted + * successfully, set the boostable flag + */ + if (unlikely(p->ainsn.boostable == 0)) + p->ainsn.boostable = 1; + } else if (ret < 0) { + /* + * We don't allow kprobes on mtmsr(d)/rfi(d), etc. + * So, we should never get here... but, its still + * good to catch them, just in case... + */ + printk("Can't step on instruction %x\n", insn); + BUG(); + } else if (ret == 0) + /* This instruction can't be boosted */ + p->ainsn.boostable = -1; + + return ret; +} +NOKPROBE_SYMBOL(try_to_emulate); + int kprobe_handler(struct pt_regs *regs) { struct kprobe *p; @@ -193,6 +307,14 @@ int kprobe_handler(struct pt_regs *regs) kprobes_inc_nmissed_count(p); prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_REENTER; + if (p->ainsn.boostable >= 0) { + ret = try_to_emulate(p, regs); + + if (ret > 0) { + restore_previous_kprobe(kcb); + return 1; + } + } return 1; } else { if (*addr != BREAKPOINT_INSTRUCTION) { @@ -209,7 +331,9 @@ int kprobe_handler(struct pt_regs *regs) } p = __this_cpu_read(current_kprobe); if (p->break_handler && p->break_handler(p, regs)) { - goto ss_probe; + if (!skip_singlestep(p, regs, kcb)) + goto ss_probe; + ret = 1; } } goto no_kprobe; @@ -247,18 +371,9 @@ int kprobe_handler(struct pt_regs *regs) ss_probe: if (p->ainsn.boostable >= 0) { - unsigned int insn = *p->ainsn.insn; + ret = try_to_emulate(p, regs); - /* regs->nip is also adjusted if emulate_step returns 1 */ - ret = emulate_step(regs, insn); if (ret > 0) { - /* - * Once this instruction has been boosted - * successfully, set the boostable flag - */ - if (unlikely(p->ainsn.boostable == 0)) - p->ainsn.boostable = 1; - if (p->post_handler) p->post_handler(p, regs, 0); @@ -266,17 +381,7 @@ ss_probe: reset_current_kprobe(); preempt_enable_no_resched(); return 1; - } else if (ret < 0) { - /* - * We don't allow kprobes on mtmsr(d)/rfi(d), etc. - * So, we should never get here... but, its still - * good to catch them, just in case... - */ - printk("Can't step on instruction %x\n", insn); - BUG(); - } else if (ret == 0) - /* This instruction can't be boosted */ - p->ainsn.boostable = -1; + } } prepare_singlestep(p, regs); kcb->kprobe_status = KPROBE_HIT_SS; diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 2282bf4e63cd..ec60ed0d4aad 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -243,10 +243,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p) /* * 2. branch to optimized_callback() and emulate_step() */ - kprobe_lookup_name("optimized_callback", op_callback_addr); - kprobe_lookup_name("emulate_step", emulate_step_addr); + op_callback_addr = (kprobe_opcode_t *)ppc_kallsyms_lookup_name("optimized_callback"); + emulate_step_addr = (kprobe_opcode_t *)ppc_kallsyms_lookup_name("emulate_step"); if (!op_callback_addr || !emulate_step_addr) { - WARN(1, "kprobe_lookup_name() failed\n"); + WARN(1, "Unable to lookup optimized_callback()/emulate_step()\n"); goto error; } |