Re: [PATCH] mm/kprobes: Add generic kprobe_fault_handler() fallback definition
flat view
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2019-07-05 10:30:45
Also in:
linux-arm-kernel, linux-mips, linux-mm, linux-s390, linux-sh, lkml, sparclinux
Hi Anshuman, On Fri, 5 Jul 2019 11:00:29 +0530 Anshuman Khandual [off-list ref] wrote:
Architectures like parisc enable CONFIG_KROBES without having a definition for kprobe_fault_handler() which results in a build failure.
Hmm, as far as I can see, kprobe_fault_handler() is closed inside each arch specific code. The reason why include/linux/kprobes.h defines dummy inline function is only for !CONFIG_KPROBES case.
Arch needs to provide kprobe_fault_handler() as it is platform specific and cannot have a generic working alternative. But in the event when platform lacks such a definition there needs to be a fallback.
Wait, indeed that each arch need to implement it, but that is for calling kprobe->fault_handler() as user expected. Hmm, why not fixing those architecture implementations?
This adds a stub kprobe_fault_handler() definition which not only prevents a build failure but also makes sure that kprobe_page_fault() if called will always return negative in absence of a sane platform specific alternative.
I don't like introducing this complicated macro only for avoiding (not fixing) build error. To fix that, kprobes on parisc should implement kprobe_fault_handler correctly (and call kprobe->fault_handler). BTW, even if you need such generic stub, please use a weak function instead of macros for every arch headers.
While here wrap kprobe_page_fault() in CONFIG_KPROBES. This enables stud definitions for generic kporbe_fault_handler() and kprobes_built_in() can just be dropped. Only on x86 it needs to be added back locally as it gets used in a !CONFIG_KPROBES function do_general_protection().
If you want to remove kprobes_built_in(), you should replace it with IS_ENABLED(CONFIG_KPROBES), instead of this... Thank you,
quoted hunk ↗ jump to hunk
Cc: Vineet Gupta <redacted> Cc: Russell King <linux@armlinux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <redacted> Cc: Ralf Baechle <redacted> Cc: Paul Burton <redacted> Cc: James Hogan <jhogan@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <redacted> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <redacted> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <redacted> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Naveen N. Rao" <redacted> Cc: Anil S Keshavamurthy <redacted> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Allison Randal <redacted> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Enrico Weigelt <info@metux.net> Cc: Richard Fontana <redacted> Cc: Kate Stewart <redacted> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: x86@kernel.org Cc: linux-snps-arc@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-ia64@vger.kernel.org Cc: linux-mips@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: sparclinux@vger.kernel.org Signed-off-by: Anshuman Khandual <redacted> --- arch/arc/include/asm/kprobes.h | 1 + arch/arm/include/asm/kprobes.h | 1 + arch/arm64/include/asm/kprobes.h | 1 + arch/ia64/include/asm/kprobes.h | 1 + arch/mips/include/asm/kprobes.h | 1 + arch/powerpc/include/asm/kprobes.h | 1 + arch/s390/include/asm/kprobes.h | 1 + arch/sh/include/asm/kprobes.h | 1 + arch/sparc/include/asm/kprobes.h | 1 + arch/x86/include/asm/kprobes.h | 6 ++++++ include/linux/kprobes.h | 32 ++++++++++++++++++------------ 11 files changed, 34 insertions(+), 13 deletions(-)diff --git a/arch/arc/include/asm/kprobes.h b/arch/arc/include/asm/kprobes.h index 2134721dce44..ee8efe256675 100644 --- a/arch/arc/include/asm/kprobes.h +++ b/arch/arc/include/asm/kprobes.h@@ -45,6 +45,7 @@ struct kprobe_ctlblk { struct prev_kprobe prev_kprobe; }; +#define kprobe_fault_handler kprobe_fault_handler int kprobe_fault_handler(struct pt_regs *regs, unsigned long cause); void kretprobe_trampoline(void); void trap_is_kprobe(unsigned long address, struct pt_regs *regs);diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h index 213607a1f45c..660f877b989f 100644 --- a/arch/arm/include/asm/kprobes.h +++ b/arch/arm/include/asm/kprobes.h@@ -38,6 +38,7 @@ struct kprobe_ctlblk { struct prev_kprobe prev_kprobe; }; +#define kprobe_fault_handler kprobe_fault_handler void arch_remove_kprobe(struct kprobe *); int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); int kprobe_exceptions_notify(struct notifier_block *self,diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h index 97e511d645a2..667773f75616 100644 --- a/arch/arm64/include/asm/kprobes.h +++ b/arch/arm64/include/asm/kprobes.h@@ -42,6 +42,7 @@ struct kprobe_ctlblk { struct kprobe_step_ctx ss_ctx; }; +#define kprobe_fault_handler kprobe_fault_handler void arch_remove_kprobe(struct kprobe *); int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); int kprobe_exceptions_notify(struct notifier_block *self,diff --git a/arch/ia64/include/asm/kprobes.h b/arch/ia64/include/asm/kprobes.h index c5cf5e4fb338..c321e8585089 100644 --- a/arch/ia64/include/asm/kprobes.h +++ b/arch/ia64/include/asm/kprobes.h@@ -106,6 +106,7 @@ struct arch_specific_insn { unsigned short slot; }; +#define kprobe_fault_handler kprobe_fault_handler extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data);diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h index 68b1e5d458cf..d1efe991ea22 100644 --- a/arch/mips/include/asm/kprobes.h +++ b/arch/mips/include/asm/kprobes.h@@ -40,6 +40,7 @@ do { \ #define kretprobe_blacklist_size 0 +#define kprobe_fault_handler kprobe_fault_handler void arch_remove_kprobe(struct kprobe *p); int kprobe_fault_handler(struct pt_regs *regs, int trapnr);diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h index 66b3f2983b22..c94f375ec957 100644 --- a/arch/powerpc/include/asm/kprobes.h +++ b/arch/powerpc/include/asm/kprobes.h@@ -84,6 +84,7 @@ struct arch_optimized_insn { kprobe_opcode_t *insn; }; +#define kprobe_fault_handler kprobe_fault_handler 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);diff --git a/arch/s390/include/asm/kprobes.h b/arch/s390/include/asm/kprobes.h index b106aa29bf55..0ecaebb78092 100644 --- a/arch/s390/include/asm/kprobes.h +++ b/arch/s390/include/asm/kprobes.h@@ -73,6 +73,7 @@ struct kprobe_ctlblk { void arch_remove_kprobe(struct kprobe *p); void kretprobe_trampoline(void); +#define kprobe_fault_handler kprobe_fault_handler int kprobe_fault_handler(struct pt_regs *regs, int trapnr); int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data);diff --git a/arch/sh/include/asm/kprobes.h b/arch/sh/include/asm/kprobes.h index 6171682f7798..637a698393c0 100644 --- a/arch/sh/include/asm/kprobes.h +++ b/arch/sh/include/asm/kprobes.h@@ -45,6 +45,7 @@ struct kprobe_ctlblk { struct prev_kprobe prev_kprobe; }; +#define kprobe_fault_handler kprobe_fault_handler extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data);diff --git a/arch/sparc/include/asm/kprobes.h b/arch/sparc/include/asm/kprobes.h index bfcaa6326c20..9aa4d25a45a8 100644 --- a/arch/sparc/include/asm/kprobes.h +++ b/arch/sparc/include/asm/kprobes.h@@ -47,6 +47,7 @@ struct kprobe_ctlblk { struct prev_kprobe prev_kprobe; }; +#define kprobe_fault_handler kprobe_fault_handler int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); int kprobe_fault_handler(struct pt_regs *regs, int trapnr);diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h index 5dc909d9ad81..1af2b6db13bd 100644 --- a/arch/x86/include/asm/kprobes.h +++ b/arch/x86/include/asm/kprobes.h@@ -101,11 +101,17 @@ struct kprobe_ctlblk { struct prev_kprobe prev_kprobe; }; +#define kprobe_fault_handler kprobe_fault_handler extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); extern int kprobe_int3_handler(struct pt_regs *regs); extern int kprobe_debug_handler(struct pt_regs *regs); +#else +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) +{ + return 0; +} #endif /* CONFIG_KPROBES */ #endif /* _ASM_X86_KPROBES_H */diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 04bdaf01112c..e106f3018804 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h@@ -182,11 +182,19 @@ DECLARE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); /* * For #ifdef avoidance: */ -static inline int kprobes_built_in(void) + +/* + * Architectures need to override this with their own implementation + * if they care to call kprobe_page_fault(). This will just ensure + * that kprobe_page_fault() returns false when called without having + * a proper platform specific definition for kprobe_fault_handler(). + */ +#ifndef kprobe_fault_handler +static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) { - return 1; + return 0; } - +#endif #ifdef CONFIG_KRETPROBES extern void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs);@@ -375,14 +383,6 @@ void free_insn_page(void *page); #else /* !CONFIG_KPROBES: */ -static inline int kprobes_built_in(void) -{ - return 0; -} -static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) -{ - return 0; -} static inline struct kprobe *get_kprobe(void *addr) { return NULL;@@ -458,12 +458,11 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr) } #endif +#ifdef CONFIG_KPROBES /* Returns true if kprobes handled the fault */ static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, unsigned int trap) { - if (!kprobes_built_in()) - return false; if (user_mode(regs)) return false; /*@@ -476,5 +475,12 @@ static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, return false; return kprobe_fault_handler(regs, trap); } +#else +static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, + unsigned int trap) +{ + return false; +} +#endif #endif /* _LINUX_KPROBES_H */-- 2.20.1
-- Masami Hiramatsu [off-list ref]