[RFC V3] mm: Generalize and rename notify_page_fault() as kprobe_page_fault()
From: Anshuman Khandual <hidden>
Date: 2019-06-07 10:35:57
Very similar definitions for notify_page_fault() are being used by multiple
architectures duplicating much of the same code. This attempts to unify all
of them into a generic implementation, rename it as kprobe_page_fault() and
then move it to a common header.
kprobes_built_in() can detect CONFIG_KPROBES, hence new kprobe_page_fault()
need not be wrapped again within CONFIG_KPROBES. Trap number argument can
now contain upto an 'unsigned int' accommodating all possible platforms.
kprobe_page_fault() goes the x86 way while dealing with preemption context.
As explained in these following commits the invoking context in itself must
be non-preemptible for kprobes processing context irrespective of whether
kprobe_running() or perhaps smp_processor_id() is safe or not. It does not
make much sense to continue when original context is preemptible. Instead
just bail out earlier.
commit a980c0ef9f6d
("x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify()")
commit b506a9d08bae ("x86: code clarification patch to Kprobes arch code")
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@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
Cc: x86@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Christophe Leroy <redacted>
Cc: Stephen Rothwell <redacted>
Cc: Andrey Konovalov <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <redacted>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <redacted>
Cc: Martin Schwidefsky <redacted>
Cc: Heiko Carstens <redacted>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <redacted>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Anshuman Khandual <redacted>
---
Testing:
- Build and boot tested on arm64 and x86
- Build tested on some other archs (arm, sparc64, alpha, powerpc etc)
Changes in RFC V3:
- Updated the commit message with an explaination for new preemption behaviour
- Moved notify_page_fault() to kprobes.h with 'static nokprobe_inline' per Matthew
- Changed notify_page_fault() return type from int to bool per Michael Ellerman
- Renamed notify_page_fault() as kprobe_page_fault() per Peterz
Changes in RFC V2: (https://patchwork.kernel.org/patch/10974221/)
- Changed generic notify_page_fault() per Mathew Wilcox
- Changed x86 to use new generic notify_page_fault()
- s/must not/need not/ in commit message per Matthew Wilcox
Changes in RFC V1: (https://patchwork.kernel.org/patch/10968273/)
arch/arm/mm/fault.c | 24 +-----------------------
arch/arm64/mm/fault.c | 24 +-----------------------
arch/ia64/mm/fault.c | 24 +-----------------------
arch/powerpc/mm/fault.c | 23 ++---------------------
arch/s390/mm/fault.c | 16 +---------------
arch/sh/mm/fault.c | 18 ++----------------
arch/sparc/mm/fault_64.c | 16 +---------------
arch/x86/mm/fault.c | 21 ++-------------------
include/linux/kprobes.h | 16 ++++++++++++++++
9 files changed, 27 insertions(+), 155 deletions(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 58f69fa..94a97a4 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c@@ -30,28 +30,6 @@ #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'.
@@ -266,7 +244,7 @@ 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 a30818e..8fe4bbc 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c@@ -70,28 +70,6 @@ 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");
@@ -446,7 +424,7 @@ 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; tsk = current;
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 5baeb02..22582f8 100644
--- 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/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index ec6b7ad..f20ee668 100644
--- 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.
@@ -462,8 +442,9 @@ 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; + int 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 91ce03f..bb77a2c 100644
--- 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. * Access register mode is impossible, ignore space == 3.
@@ -411,7 +397,7 @@ 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 6defd2c6..74cd4ac 100644
--- 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, struct task_struct *tsk)
@@ -415,14 +401,14 @@ 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 8f8a604..6865f9c 100644
--- 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 46df4c6..5400f4e 100644
--- 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: *
@@ -1280,7 +1263,7 @@ 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; /*
@@ -1311,7 +1294,7 @@ 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 443d980..064dd15 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h@@ -458,4 +458,20 @@ static inline bool is_kprobe_optinsn_slot(unsigned long addr) } #endif +static nokprobe_inline bool kprobe_page_fault(struct pt_regs *regs, + unsigned int trap) +{ + int ret = 0; + + /* + * To be potentially processing a kprobe fault and to be allowed + * to call kprobe_running(), we have to be non-preemptible. + */ + if (kprobes_built_in() && !preemptible() && !user_mode(regs)) { + if (kprobe_running() && kprobe_fault_handler(regs, trap)) + ret = 1; + } + return ret; +} + #endif /* _LINUX_KPROBES_H */
--
2.7.4