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Subject[PATCHv2] kprobes: Introduce is_kprobe_fault()
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Date
Use a central is_kprobe_fault() inline in kprobes.h to remove all
of the arch-dependant, practically identical implementations in
avr32, ia64, powerpc, s390, sparc64, and x86.

avr32 was the only arch without the preempt_disable/enable pair
in its notify_page_fault implementation.

This uncovered a possible bug in the s390 version as that purely
copied the x86 version unconditionally passing 14 as the trapnr
rather than the error_code parameter.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
---
Andrew, update to my previous patch, with relevant (I hope)
maintainers CC'd. Patch against v2.6.24-rc7
X86_32 is ignored for now as it truly needs user_mode_vm
in the implementation.

arch/avr32/mm/fault.c | 21 +--------------------
arch/ia64/mm/fault.c | 24 +-----------------------
arch/powerpc/mm/fault.c | 25 +------------------------
arch/s390/mm/fault.c | 25 +------------------------
arch/sparc64/mm/fault.c | 23 +----------------------
arch/x86/mm/fault_64.c | 26 ++------------------------
include/linux/kprobes.h | 19 +++++++++++++++++++
7 files changed, 26 insertions(+), 137 deletions(-)
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 6560cb1..a95cce2 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -20,25 +20,6 @@
#include <asm/tlb.h>
#include <asm/uaccess.h>

-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs, int trap)
-{
- int ret = 0;
-
- if (!user_mode(regs)) {
- if (kprobe_running() && kprobe_fault_handler(regs, trap))
- ret = 1;
- }
-
- return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs, int trap)
-{
- return 0;
-}
-#endif
-
int exception_trace = 1;

/*
@@ -66,7 +47,7 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
int code;
int fault;

- if (notify_page_fault(regs, ecr))
+ if (is_kprobe_fault(regs, ecr))
return;

address = sysreg_read(TLBEAR);
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 7571076..1696805 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -18,28 +18,6 @@

extern void 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() && kprobes_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.
@@ -106,7 +84,7 @@ 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 (is_kprobe_fault(regs, TRAP_BRKPT))
return;

down_read(&mm->mmap_sem);
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 8135da0..00df6f9 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -39,29 +39,6 @@
#include <asm/tlbflush.h>
#include <asm/siginfo.h>

-
-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- int ret = 0;
-
- /* kprobe_running() needs smp_processor_id() */
- if (!user_mode(regs)) {
- preempt_disable();
- if (kprobe_running() && kprobe_fault_handler(regs, 11))
- ret = 1;
- preempt_enable();
- }
-
- return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- return 0;
-}
-#endif
-
/*
* Check whether the instruction at regs->nip is a store using
* an update addressing form which will update r1.
@@ -164,7 +141,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
is_write = error_code & ESR_DST;
#endif /* CONFIG_4xx || CONFIG_BOOKE */

- if (notify_page_fault(regs))
+ if (is_kprobe_fault(regs, 11))
return 0;

if (trap == 0x300) {
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 2456b52..59d3f0e 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -51,29 +51,6 @@ extern int sysctl_userprocess_debug;

extern void die(const char *,struct pt_regs *,long);

-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs, long err)
-{
- int ret = 0;
-
- /* kprobe_running() needs smp_processor_id() */
- if (!user_mode(regs)) {
- preempt_disable();
- if (kprobe_running() && kprobe_fault_handler(regs, 14))
- ret = 1;
- preempt_enable();
- }
-
- return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs, long err)
-{
- return 0;
-}
-#endif
-
-
/*
* Unlock any spinlocks which will prevent us from getting the
* message out.
@@ -309,7 +286,7 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int write)
int si_code;
int fault;

- if (notify_page_fault(regs, error_code))
+ if (is_kprobe_fault(regs, 14))
return;

tsk = current;
diff --git a/arch/sparc64/mm/fault.c b/arch/sparc64/mm/fault.c
index e2027f2..bb5c36a 100644
--- a/arch/sparc64/mm/fault.c
+++ b/arch/sparc64/mm/fault.c
@@ -31,27 +31,6 @@
#include <asm/sections.h>
#include <asm/mmu_context.h>

-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- int ret = 0;
-
- /* kprobe_running() needs smp_processor_id() */
- if (!user_mode(regs)) {
- preempt_disable();
- if (kprobe_running() && kprobe_fault_handler(regs, 0))
- ret = 1;
- preempt_enable();
- }
- return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- return 0;
-}
-#endif
-
/*
* To debug kernel to catch accesses to certain virtual/physical addresses.
* Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints.
@@ -280,7 +259,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)

fault_code = get_thread_fault_code();

- if (notify_page_fault(regs))
+ if (is_kprobe_fault(regs, 0))
return;

si_code = SEGV_MAPERR;
diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c
index 0e26230..376e218 100644
--- a/arch/x86/mm/fault_64.c
+++ b/arch/x86/mm/fault_64.c
@@ -41,28 +41,6 @@
#define PF_RSVD (1<<3)
#define PF_INSTR (1<<4)

-#ifdef CONFIG_KPROBES
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- int ret = 0;
-
- /* kprobe_running() needs smp_processor_id() */
- if (!user_mode(regs)) {
- preempt_disable();
- if (kprobe_running() && kprobe_fault_handler(regs, 14))
- ret = 1;
- preempt_enable();
- }
-
- return ret;
-}
-#else
-static inline int notify_page_fault(struct pt_regs *regs)
-{
- return 0;
-}
-#endif
-
/* Sometimes the CPU reports invalid exceptions on prefetch.
Check that here and ignore.
Opcode checker based on code by Richard Brunner */
@@ -343,7 +321,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
if (vmalloc_fault(address) >= 0)
return;
}
- if (notify_page_fault(regs))
+ if (is_kprobe_fault(regs, 14))
return;
/*
* Don't take the mm semaphore here. If we fixup a prefetch
@@ -352,7 +330,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
goto bad_area_nosemaphore;
}

- if (notify_page_fault(regs))
+ if (is_kprobe_fault(regs, 14))
return;

if (likely(regs->eflags & X86_EFLAGS_IF))
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 8189158..65c1ffb 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -36,6 +36,7 @@
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/mutex.h>
+#include <linux/hardirq.h>

#ifdef CONFIG_KPROBES
#include <asm/kprobes.h>
@@ -203,6 +204,20 @@ static inline struct kprobe *kprobe_running(void)
return (__get_cpu_var(current_kprobe));
}

+/*
+ * If it is a kprobe pagefault we can not be premptible so return before
+ * calling kprobe_running() as it will assert on smp_processor_id if
+ * preemption is enabled.
+ */
+static inline int is_kprobe_fault(struct pt_regs *regs, int trapnr)
+{
+ if (!user_mode(regs) && !preemptible() && kprobe_running() &&
+ kprobe_fault_handler(regs, trapnr))
+ return 1;
+ else
+ return 0;
+}
+
static inline void reset_current_kprobe(void)
{
__get_cpu_var(current_kprobe) = NULL;
@@ -237,6 +252,10 @@ static inline struct kprobe *kprobe_running(void)
{
return NULL;
}
+static inline int is_kprobe_fault(struct pt_regs *regs, int trapnr)
+{
+ return 0;
+}
static inline int register_kprobe(struct kprobe *p)
{
return -ENOSYS;
--
1.5.4.rc2.1117.ge5809


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