[PATCH v2 2/2] powerpc: kprobes: invoke handlers directly
From: Naveen N. Rao <hidden>
Date: 2016-11-21 17:07:06
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
... rather than through notify_die(), to reduce path taken for handling
kprobes. Similar to commit 6f6343f53d13 ("kprobes/x86: Call exception
handlers directly from do_int3/do_debug").
While at it, rename post_kprobe_handler() to kprobe_post_handler() for
more uniform naming.
Reported-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <redacted>
---
Changes since v1:
- Removed CONFIG_KPROBES guard in traps.c
- Introduce CONFIG_KPROBES guard in asm/kprobes.h to prevent conflicts when
including both linux/kprobes.h as well as asm/kprobes.h
arch/powerpc/include/asm/kprobes.h | 7 +++++++
arch/powerpc/kernel/kprobes.c | 29 +++++++----------------------
arch/powerpc/kernel/traps.c | 13 +++++++++++++
3 files changed, 27 insertions(+), 22 deletions(-)
diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
index 2c9759bd..da30dc3 100644
--- a/arch/powerpc/include/asm/kprobes.h
+++ b/arch/powerpc/include/asm/kprobes.h@@ -32,6 +32,7 @@ #include <asm/probes.h> #include <asm/code-patching.h> +#ifdef CONFIG_KPROBES #define __ARCH_WANT_KPROBES_INSN_SLOT struct pt_regs;
@@ -127,5 +128,11 @@ struct kprobe_ctlblk { extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); +extern int kprobe_handler(struct pt_regs *regs); +extern int kprobe_post_handler(struct pt_regs *regs); +#else +static int kprobe_handler(struct pt_regs *regs) { return 0; } +static int kprobe_post_handler(struct pt_regs *regs) { return 0; } +#endif /* CONFIG_KPROBES */ #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_KPROBES_H */
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 9479d8e..ad108b8 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c@@ -140,13 +140,16 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, regs->link = (unsigned long)kretprobe_trampoline; } -static int __kprobes kprobe_handler(struct pt_regs *regs) +int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; unsigned int *addr = (unsigned int *)regs->nip; struct kprobe_ctlblk *kcb; + if (user_mode(regs)) + return 0; + /* * We don't want to be preempted for the entire * duration of kprobe processing
@@ -359,12 +362,12 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p, * single-stepped a copy of the instruction. The address of this * copy is p->ainsn.insn. */ -static int __kprobes post_kprobe_handler(struct pt_regs *regs) +int __kprobes kprobe_post_handler(struct pt_regs *regs) { struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - if (!cur) + if (!cur || user_mode(regs)) return 0; /* make sure we got here for instruction we have a kprobe on */
@@ -470,25 +473,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) int __kprobes kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data) { - struct die_args *args = (struct die_args *)data; - int ret = NOTIFY_DONE; - - if (args->regs && user_mode(args->regs)) - return ret; - - switch (val) { - case DIE_BPT: - if (kprobe_handler(args->regs)) - ret = NOTIFY_STOP; - break; - case DIE_SSTEP: - if (post_kprobe_handler(args->regs)) - ret = NOTIFY_STOP; - break; - default: - break; - } - return ret; + return NOTIFY_DONE; } unsigned long arch_deref_entry_point(void *entry)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 91d278c..38d5fbf 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c@@ -64,6 +64,7 @@ #include <asm/asm-prototypes.h> #include <asm/hmi.h> #include <sysdev/fsl_pci.h> +#include <asm/kprobes.h> #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC) int (*__debugger)(struct pt_regs *regs) __read_mostly;
@@ -824,6 +825,9 @@ void single_step_exception(struct pt_regs *regs) clear_single_step(regs); + if (kprobe_post_handler(regs)) + return; + if (notify_die(DIE_SSTEP, "single_step", regs, 5, 5, SIGTRAP) == NOTIFY_STOP) goto bail;
@@ -1177,6 +1181,9 @@ void program_check_exception(struct pt_regs *regs) if (debugger_bpt(regs)) goto bail; + if (kprobe_handler(regs)) + goto bail; + /* trap exception */ if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP) == NOTIFY_STOP)
@@ -1745,6 +1752,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status) return; } + if (kprobe_post_handler(regs)) + return; + if (notify_die(DIE_SSTEP, "block_step", regs, 5, 5, SIGTRAP) == NOTIFY_STOP) { return;
@@ -1759,6 +1769,9 @@ void DebugException(struct pt_regs *regs, unsigned long debug_status) /* Clear the instruction completion event */ mtspr(SPRN_DBSR, DBSR_IC); + if (kprobe_post_handler(regs)) + return; + if (notify_die(DIE_SSTEP, "single_step", regs, 5, 5, SIGTRAP) == NOTIFY_STOP) { return;
--
2.10.2