mm, kprobes: generalize and rename notify_page_fault() as kprobe_page_fault()

Architectures which support kprobes have very similar boilerplate around
calling kprobe_fault_handler().  Use a helper function in kprobes.h to
unify them, based on the x86 code.

This changes the behaviour for other architectures when preemption is
enabled.  Previously, they would have disabled preemption while calling
the kprobe handler.  However, preemption would be disabled if this fault
was due to a kprobe, so we know the fault was not due to a kprobe
handler and can simply return failure.

This behaviour was introduced in commit a980c0ef9f6d ("x86/kprobes:
Refactor kprobes_fault() like kprobe_exceptions_notify()")

[[email protected]: export kprobe_fault_handler()]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Anshuman Khandual <[email protected]>
Reviewed-by: Dave Hansen <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Russell King <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Ralf Baechle <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 0e417233dad7209255c370d3cee65ee336ec34ab..890eeaac3cbbaea361c7771b446ba5cc3f68cd05 100644 (file)
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -27,28 +27,6 @@
 
 #ifdef CONFIG_MMU
 
-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
-{
-       int ret = 0;
-
-       if (!user_mode(regs)) {
-               /* kprobe_running() needs smp_processor_id() */
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, fsr))
-                       ret = 1;
-               preempt_enable();
-       }
-
-       return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
-{
-       return 0;
-}
-#endif
-
 /*
  * This is useful to dump out the page tables associated with
  * 'addr' in mm 'mm'.
@@ -265,7 +243,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
        vm_fault_t fault;
        unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
-       if (notify_page_fault(regs, fsr))
+       if (kprobe_page_fault(regs, fsr))
                return 0;
 
        tsk = current;

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index c8c61b1eb479b358a614cb56907b10422e00f34b..9568c116ac7fc629994790a3d06125d5e2f44ca9 100644 (file)
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -59,28 +59,6 @@ static inline const struct fault_info *esr_to_debug_fault_info(unsigned int esr)
        return debug_fault_info + DBG_ESR_EVT(esr);
 }
 
-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
-{
-       int ret = 0;
-
-       /* kprobe_running() needs smp_processor_id() */
-       if (!user_mode(regs)) {
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, esr))
-                       ret = 1;
-               preempt_enable();
-       }
-
-       return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
-{
-       return 0;
-}
-#endif
-
 static void data_abort_decode(unsigned int esr)
 {
        pr_alert("Data abort info:\n");
@@ -434,7 +412,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
        unsigned long vm_flags = VM_READ | VM_WRITE;
        unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
-       if (notify_page_fault(regs, esr))
+       if (kprobe_page_fault(regs, esr))
                return 0;
 
        /*

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 3c3a283d3172bad2109dc9de8805a68e2a3357f9..c2f299fe9e04a88c8bc9675a5295141a4a0f82eb 100644 (file)
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -21,28 +21,6 @@
 
 extern int die(char *, struct pt_regs *, long);
 
-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs, int trap)
-{
-       int ret = 0;
-
-       if (!user_mode(regs)) {
-               /* kprobe_running() needs smp_processor_id() */
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, trap))
-                       ret = 1;
-               preempt_enable();
-       }
-
-       return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs, int trap)
-{
-       return 0;
-}
-#endif
-
 /*
  * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
  * (inside region 5, on ia64) and that page is present.
@@ -116,7 +94,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
        /*
         * This is to handle the kprobes on user space access instructions
         */
-       if (notify_page_fault(regs, TRAP_BRKPT))
+       if (kprobe_page_fault(regs, TRAP_BRKPT))
                return;
 
        if (user_mode(regs))

diff --git a/arch/mips/include/asm/kprobes.h b/arch/mips/include/asm/kprobes.h
index 3cf8e4d5fa28298c2817411c517890c803b103b3..68b1e5d458cfb6a28278289c37ca78e94e61230d 100644 (file)
--- a/arch/mips/include/asm/kprobes.h
+++ b/arch/mips/include/asm/kprobes.h
@@ -41,6 +41,7 @@ do {                                                                  \
 #define kretprobe_blacklist_size 0
 
 void arch_remove_kprobe(struct kprobe *p);
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 
 /* Architecture specific copy of original instruction*/
 struct arch_specific_insn {

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 81ba1d3c367c96addbd795bd0d8998e5607e1895..6cfae2411c044de5c3ee48a4b74a63167323d5fc 100644 (file)
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -398,7 +398,7 @@ out:
        return 1;
 }
 
-static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
        struct kprobe *cur = kprobe_running();
        struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index d989592b6fc838ac605854658e36c91b39d47bb9..8432c281de921440cc0cffe9d14d8879f565a0e9 100644 (file)
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -42,26 +42,6 @@
 #include <asm/debug.h>
 #include <asm/kup.h>
 
-static inline bool notify_page_fault(struct pt_regs *regs)
-{
-       bool ret = false;
-
-#ifdef CONFIG_KPROBES
-       /* kprobe_running() needs smp_processor_id() */
-       if (!user_mode(regs)) {
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, 11))
-                       ret = true;
-               preempt_enable();
-       }
-#endif /* CONFIG_KPROBES */
-
-       if (unlikely(debugger_fault_handler(regs)))
-               ret = true;
-
-       return ret;
-}
-
 /*
  * Check whether the instruction inst is a store using
  * an update addressing form which will update r1.
@@ -461,8 +441,9 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
        int is_write = page_fault_is_write(error_code);
        vm_fault_t fault, major = 0;
        bool must_retry = false;
+       bool kprobe_fault = kprobe_page_fault(regs, 11);
 
-       if (notify_page_fault(regs))
+       if (unlikely(debugger_fault_handler(regs) || kprobe_fault))
                return 0;
 
        if (unlikely(page_fault_is_bad(error_code))) {

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 0ba174f779daf54abd2b3a4bf91fb3f9d8f8d69a..63507662828fd90e008a7e1b254496a57d548a16 100644 (file)
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -67,20 +67,6 @@ static int __init fault_init(void)
 }
 early_initcall(fault_init);
 
-static inline int notify_page_fault(struct pt_regs *regs)
-{
-       int ret = 0;
-
-       /* kprobe_running() needs smp_processor_id() */
-       if (kprobes_built_in() && !user_mode(regs)) {
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, 14))
-                       ret = 1;
-               preempt_enable();
-       }
-       return ret;
-}
-
 /*
  * Find out which address space caused the exception.
  */
@@ -412,7 +398,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
         */
        clear_pt_regs_flag(regs, PIF_PER_TRAP);
 
-       if (notify_page_fault(regs))
+       if (kprobe_page_fault(regs, 14))
                return 0;
 
        mm = tsk->mm;

diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 3093bc3721386bcdd40aca3aae77da95e5980da6..5f51456f4fc7167a2af3e02b6774ca48375e73fc 100644 (file)
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -24,20 +24,6 @@
 #include <asm/tlbflush.h>
 #include <asm/traps.h>
 
-static inline int notify_page_fault(struct pt_regs *regs, int trap)
-{
-       int ret = 0;
-
-       if (kprobes_built_in() && !user_mode(regs)) {
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, trap))
-                       ret = 1;
-               preempt_enable();
-       }
-
-       return ret;
-}
-
 static void
 force_sig_info_fault(int si_signo, int si_code, unsigned long address)
 {
@@ -412,14 +398,14 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
        if (unlikely(fault_in_kernel_space(address))) {
                if (vmalloc_fault(address) >= 0)
                        return;
-               if (notify_page_fault(regs, vec))
+               if (kprobe_page_fault(regs, vec))
                        return;
 
                bad_area_nosemaphore(regs, error_code, address);
                return;
        }
 
-       if (unlikely(notify_page_fault(regs, vec)))
+       if (unlikely(kprobe_page_fault(regs, vec)))
                return;
 
        /* Only enable interrupts if they were on before the fault */

diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index 83fda4d9c3b240e0c2a004dfb50c3200469cd84c..2371fb6b97e4dd6e463349fb55583ee3cafdf43e 100644 (file)
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -38,20 +38,6 @@
 
 int show_unhandled_signals = 1;
 
-static inline __kprobes int notify_page_fault(struct pt_regs *regs)
-{
-       int ret = 0;
-
-       /* kprobe_running() needs smp_processor_id() */
-       if (kprobes_built_in() && !user_mode(regs)) {
-               preempt_disable();
-               if (kprobe_running() && kprobe_fault_handler(regs, 0))
-                       ret = 1;
-               preempt_enable();
-       }
-       return ret;
-}
-
 static void __kprobes unhandled_fault(unsigned long address,
                                      struct task_struct *tsk,
                                      struct pt_regs *regs)
@@ -285,7 +271,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 
        fault_code = get_thread_fault_code();
 
-       if (notify_page_fault(regs))
+       if (kprobe_page_fault(regs, 0))
                goto exit_exception;
 
        si_code = SEGV_MAPERR;

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 794f364cb8829ef5a719cafbc26766e68d08ca9e..d1634c59ed561cea4b58c8bd8bd3e2b795a74594 100644 (file)
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -46,23 +46,6 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr)
        return 0;
 }
 
-static nokprobe_inline int kprobes_fault(struct pt_regs *regs)
-{
-       if (!kprobes_built_in())
-               return 0;
-       if (user_mode(regs))
-               return 0;
-       /*
-        * To be potentially processing a kprobe fault and to be allowed to call
-        * kprobe_running(), we have to be non-preemptible.
-        */
-       if (preemptible())
-               return 0;
-       if (!kprobe_running())
-               return 0;
-       return kprobe_fault_handler(regs, X86_TRAP_PF);
-}
-
 /*
  * Prefetch quirks:
  *
@@ -1282,7 +1265,7 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
                return;
 
        /* kprobes don't want to hook the spurious faults: */
-       if (kprobes_fault(regs))
+       if (kprobe_page_fault(regs, X86_TRAP_PF))
                return;
 
        /*
@@ -1313,7 +1296,7 @@ void do_user_addr_fault(struct pt_regs *regs,
        mm = tsk->mm;
 
        /* kprobes don't want to hook the spurious faults: */
-       if (unlikely(kprobes_fault(regs)))
+       if (unlikely(kprobe_page_fault(regs, X86_TRAP_PF)))
                return;
 
        /*

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 443d9800ca3f822855703fb26d22614ff82694bd..04bdaf01112cbd820bb8b4ac7c37353057b6f3f1 100644 (file)
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -458,4 +458,23 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr)
 }
 #endif
 
+/* 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;
+       /*
+        * To be potentially processing a kprobe fault and to be allowed
+        * to call kprobe_running(), we have to be non-preemptible.
+        */
+       if (preemptible())
+               return false;
+       if (!kprobe_running())
+               return false;
+       return kprobe_fault_handler(regs, trap);
+}
+
 #endif /* _LINUX_KPROBES_H */