* [PATCH v4] ARM64 breakpoint and single step exception hooks
@ 2013-12-04 5:50 ` Sandeepa Prabhu
0 siblings, 0 replies; 6+ messages in thread
From: Sandeepa Prabhu @ 2013-12-04 5:50 UTC (permalink / raw)
To: linux-arm-kernel
This patch adds support for breakpoint and single-step exception hooks.
v3 version of this patch is published and reviewed with arm64 kdgb and kprobes patch series [1] and [2]
[1] http://lwn.net/Articles/570648/
[2] https://lwn.net/Articles/571063/
Changes v3 -> v4:
-Incorporated review comments: http://lists.infradead.org/pipermail/linux-arm-kernel/2013-October/207372.html
-Removed unnecessary comments
-Added comments for breakpoint re-entrancy & rw locks
- Rebased on top of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64.git Branch:upstream
commit ID: dc1ccc48159d63eca5089e507c82c7d22ef60839 (Linux 3.13-rc2)
- CCing Jason Wessel, since arm64 kgdb patchset is dependant on this.
Sandeepa Prabhu (1):
arm64: support single-step and breakpoint handler hooks
arch/arm64/include/asm/debug-monitors.h | 21 ++++++++
arch/arm64/kernel/debug-monitors.c | 88 ++++++++++++++++++++++++++++++++-
arch/arm64/kernel/entry.S | 2 +
3 files changed, 110 insertions(+), 1 deletion(-)
--
1.8.1.2
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v4] ARM64 breakpoint and single step exception hooks @ 2013-12-04 5:50 ` Sandeepa Prabhu 0 siblings, 0 replies; 6+ messages in thread From: Sandeepa Prabhu @ 2013-12-04 5:50 UTC (permalink / raw) To: linux-arm-kernel Cc: linux-kernel, patches, linaro-kernel, catalin.marinas, will.deacon, Vijaya.Kumar, dsaxena, jason.wessel, steve.capper, Sandeepa Prabhu This patch adds support for breakpoint and single-step exception hooks. v3 version of this patch is published and reviewed with arm64 kdgb and kprobes patch series [1] and [2] [1] http://lwn.net/Articles/570648/ [2] https://lwn.net/Articles/571063/ Changes v3 -> v4: -Incorporated review comments: http://lists.infradead.org/pipermail/linux-arm-kernel/2013-October/207372.html -Removed unnecessary comments -Added comments for breakpoint re-entrancy & rw locks - Rebased on top of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64.git Branch:upstream commit ID: dc1ccc48159d63eca5089e507c82c7d22ef60839 (Linux 3.13-rc2) - CCing Jason Wessel, since arm64 kgdb patchset is dependant on this. Sandeepa Prabhu (1): arm64: support single-step and breakpoint handler hooks arch/arm64/include/asm/debug-monitors.h | 21 ++++++++ arch/arm64/kernel/debug-monitors.c | 88 ++++++++++++++++++++++++++++++++- arch/arm64/kernel/entry.S | 2 + 3 files changed, 110 insertions(+), 1 deletion(-) -- 1.8.1.2 ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v4] arm64: support single-step and breakpoint handler hooks 2013-12-04 5:50 ` Sandeepa Prabhu @ 2013-12-04 5:50 ` Sandeepa Prabhu -1 siblings, 0 replies; 6+ messages in thread From: Sandeepa Prabhu @ 2013-12-04 5:50 UTC (permalink / raw) To: linux-arm-kernel AArch64 Single Steping and Breakpoint debug exceptions will be used by multiple debug framworks like kprobes & kgdb. This patch implements the hooks for those frameworks to register their own handlers for handling breakpoint and single step events. Reworked the debug exception handler in entry.S: do_dbg to route software breakpoint (BRK64) exception to do_debug_exception() Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> Signed-off-by: Deepak Saxena <dsaxena@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/debug-monitors.h | 21 ++++++++ arch/arm64/kernel/debug-monitors.c | 88 ++++++++++++++++++++++++++++++++- arch/arm64/kernel/entry.S | 2 + 3 files changed, 110 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index a2232d0..6231479 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -62,6 +62,27 @@ struct task_struct; #define DBG_ARCH_ID_RESERVED 0 /* In case of ptrace ABI updates. */ +#define DBG_HOOK_HANDLED 0 +#define DBG_HOOK_ERROR 1 + +struct step_hook { + struct list_head node; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_step_hook(struct step_hook *hook); +void unregister_step_hook(struct step_hook *hook); + +struct break_hook { + struct list_head node; + u32 esr_val; + u32 esr_mask; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_break_hook(struct break_hook *hook); +void unregister_break_hook(struct break_hook *hook); + u8 debug_monitors_arch(void); void enable_debug_monitors(enum debug_el el); diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 4ae6857..636ba8b 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -187,6 +187,48 @@ static void clear_regs_spsr_ss(struct pt_regs *regs) regs->pstate = spsr; } +/* EL1 Single Step Handler hooks */ +static LIST_HEAD(step_hook); +DEFINE_RWLOCK(step_hook_lock); + +void register_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_add(&hook->node, &step_hook); + write_unlock(&step_hook_lock); +} + +void unregister_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_del(&hook->node); + write_unlock(&step_hook_lock); +} + +/* + * Call registered single step handers + * There is no Syndrome info to check for determining the handler. + * So we call all the registered handlers, until the right handler is + * found which returns zero. + */ +static int call_step_hook(struct pt_regs *regs, unsigned int esr) +{ + struct step_hook *hook; + int retval = DBG_HOOK_ERROR; + + read_lock(&step_hook_lock); + + list_for_each_entry(hook, &step_hook, node) { + retval = hook->fn(regs, esr); + if (retval == DBG_HOOK_HANDLED) + break; + } + + read_unlock(&step_hook_lock); + + return retval; +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -214,7 +256,9 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else { - /* TODO: route to KGDB */ + if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + pr_warning("Unexpected kernel single-step exception at EL1\n"); /* * Re-enable stepping since we know that we will be @@ -226,11 +270,53 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; } +/* + * Breakpoint handler is re-entrant as another breakpoint can + * hit within breakpoint handler, especically in kprobes. + * Use reader/writer locks instead of plain spinlock. + */ +static LIST_HEAD(break_hook); +DEFINE_RWLOCK(break_hook_lock); + +void register_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_add(&hook->node, &break_hook); + write_unlock(&break_hook_lock); +} + +void unregister_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_del(&hook->node); + write_unlock(&break_hook_lock); +} + +static int call_break_hook(struct pt_regs *regs, unsigned int esr) +{ + struct break_hook *hook; + int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; + + read_lock(&break_hook_lock); + list_for_each_entry(hook, &break_hook, node) + if ((esr & hook->esr_mask) == hook->esr_val) + fn = hook->fn; + read_unlock(&break_hook_lock); + + return fn ? fn(regs, esr) : DBG_HOOK_ERROR; +} + static int brk_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { siginfo_t info; + if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + + pr_warn("unexpected brk exception at %lx, esr=0x%x\n", + (long)instruction_pointer(regs), esr); + if (!user_mode(regs)) return -EFAULT; diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 4d2c6f3..32d7fe6 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -288,6 +288,8 @@ el1_dbg: /* * Debug exception handling */ + cmp x24, #ESR_EL1_EC_BRK64 // if BRK64 + cinc x24, x24, eq // set bit '0' tbz x24, #0, el1_inv // EL1 only mrs x0, far_el1 mov x2, sp // struct pt_regs -- 1.8.1.2 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v4] arm64: support single-step and breakpoint handler hooks @ 2013-12-04 5:50 ` Sandeepa Prabhu 0 siblings, 0 replies; 6+ messages in thread From: Sandeepa Prabhu @ 2013-12-04 5:50 UTC (permalink / raw) To: linux-arm-kernel Cc: linux-kernel, patches, linaro-kernel, catalin.marinas, will.deacon, Vijaya.Kumar, dsaxena, jason.wessel, steve.capper, Sandeepa Prabhu AArch64 Single Steping and Breakpoint debug exceptions will be used by multiple debug framworks like kprobes & kgdb. This patch implements the hooks for those frameworks to register their own handlers for handling breakpoint and single step events. Reworked the debug exception handler in entry.S: do_dbg to route software breakpoint (BRK64) exception to do_debug_exception() Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> Signed-off-by: Deepak Saxena <dsaxena@linaro.org> Acked-by: Will Deacon <will.deacon@arm.com> --- arch/arm64/include/asm/debug-monitors.h | 21 ++++++++ arch/arm64/kernel/debug-monitors.c | 88 ++++++++++++++++++++++++++++++++- arch/arm64/kernel/entry.S | 2 + 3 files changed, 110 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index a2232d0..6231479 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -62,6 +62,27 @@ struct task_struct; #define DBG_ARCH_ID_RESERVED 0 /* In case of ptrace ABI updates. */ +#define DBG_HOOK_HANDLED 0 +#define DBG_HOOK_ERROR 1 + +struct step_hook { + struct list_head node; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_step_hook(struct step_hook *hook); +void unregister_step_hook(struct step_hook *hook); + +struct break_hook { + struct list_head node; + u32 esr_val; + u32 esr_mask; + int (*fn)(struct pt_regs *regs, unsigned int esr); +}; + +void register_break_hook(struct break_hook *hook); +void unregister_break_hook(struct break_hook *hook); + u8 debug_monitors_arch(void); void enable_debug_monitors(enum debug_el el); diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 4ae6857..636ba8b 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -187,6 +187,48 @@ static void clear_regs_spsr_ss(struct pt_regs *regs) regs->pstate = spsr; } +/* EL1 Single Step Handler hooks */ +static LIST_HEAD(step_hook); +DEFINE_RWLOCK(step_hook_lock); + +void register_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_add(&hook->node, &step_hook); + write_unlock(&step_hook_lock); +} + +void unregister_step_hook(struct step_hook *hook) +{ + write_lock(&step_hook_lock); + list_del(&hook->node); + write_unlock(&step_hook_lock); +} + +/* + * Call registered single step handers + * There is no Syndrome info to check for determining the handler. + * So we call all the registered handlers, until the right handler is + * found which returns zero. + */ +static int call_step_hook(struct pt_regs *regs, unsigned int esr) +{ + struct step_hook *hook; + int retval = DBG_HOOK_ERROR; + + read_lock(&step_hook_lock); + + list_for_each_entry(hook, &step_hook, node) { + retval = hook->fn(regs, esr); + if (retval == DBG_HOOK_HANDLED) + break; + } + + read_unlock(&step_hook_lock); + + return retval; +} + static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -214,7 +256,9 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else { - /* TODO: route to KGDB */ + if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + pr_warning("Unexpected kernel single-step exception at EL1\n"); /* * Re-enable stepping since we know that we will be @@ -226,11 +270,53 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; } +/* + * Breakpoint handler is re-entrant as another breakpoint can + * hit within breakpoint handler, especically in kprobes. + * Use reader/writer locks instead of plain spinlock. + */ +static LIST_HEAD(break_hook); +DEFINE_RWLOCK(break_hook_lock); + +void register_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_add(&hook->node, &break_hook); + write_unlock(&break_hook_lock); +} + +void unregister_break_hook(struct break_hook *hook) +{ + write_lock(&break_hook_lock); + list_del(&hook->node); + write_unlock(&break_hook_lock); +} + +static int call_break_hook(struct pt_regs *regs, unsigned int esr) +{ + struct break_hook *hook; + int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL; + + read_lock(&break_hook_lock); + list_for_each_entry(hook, &break_hook, node) + if ((esr & hook->esr_mask) == hook->esr_val) + fn = hook->fn; + read_unlock(&break_hook_lock); + + return fn ? fn(regs, esr) : DBG_HOOK_ERROR; +} + static int brk_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { siginfo_t info; + if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + + pr_warn("unexpected brk exception at %lx, esr=0x%x\n", + (long)instruction_pointer(regs), esr); + if (!user_mode(regs)) return -EFAULT; diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 4d2c6f3..32d7fe6 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -288,6 +288,8 @@ el1_dbg: /* * Debug exception handling */ + cmp x24, #ESR_EL1_EC_BRK64 // if BRK64 + cinc x24, x24, eq // set bit '0' tbz x24, #0, el1_inv // EL1 only mrs x0, far_el1 mov x2, sp // struct pt_regs -- 1.8.1.2 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v4] arm64: support single-step and breakpoint handler hooks 2013-12-04 5:50 ` Sandeepa Prabhu @ 2013-12-17 18:17 ` Catalin Marinas -1 siblings, 0 replies; 6+ messages in thread From: Catalin Marinas @ 2013-12-17 18:17 UTC (permalink / raw) To: linux-arm-kernel On Wed, Dec 04, 2013 at 05:50:20AM +0000, Sandeepa Prabhu wrote: > AArch64 Single Steping and Breakpoint debug exceptions will be > used by multiple debug framworks like kprobes & kgdb. > > This patch implements the hooks for those frameworks to register > their own handlers for handling breakpoint and single step events. > > Reworked the debug exception handler in entry.S: do_dbg to route > software breakpoint (BRK64) exception to do_debug_exception() > > Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> > Signed-off-by: Deepak Saxena <dsaxena@linaro.org> > Acked-by: Will Deacon <will.deacon@arm.com> Thanks. Applied. -- Catalin ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v4] arm64: support single-step and breakpoint handler hooks @ 2013-12-17 18:17 ` Catalin Marinas 0 siblings, 0 replies; 6+ messages in thread From: Catalin Marinas @ 2013-12-17 18:17 UTC (permalink / raw) To: Sandeepa Prabhu Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, patches@linaro.org, linaro-kernel@lists.linaro.org, Will Deacon, Vijaya.Kumar@caviumnetworks.com, dsaxena@linaro.org, jason.wessel@windriver.com, steve.capper@linaro.org On Wed, Dec 04, 2013 at 05:50:20AM +0000, Sandeepa Prabhu wrote: > AArch64 Single Steping and Breakpoint debug exceptions will be > used by multiple debug framworks like kprobes & kgdb. > > This patch implements the hooks for those frameworks to register > their own handlers for handling breakpoint and single step events. > > Reworked the debug exception handler in entry.S: do_dbg to route > software breakpoint (BRK64) exception to do_debug_exception() > > Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> > Signed-off-by: Deepak Saxena <dsaxena@linaro.org> > Acked-by: Will Deacon <will.deacon@arm.com> Thanks. Applied. -- Catalin ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-12-17 18:17 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2013-12-04 5:50 [PATCH v4] ARM64 breakpoint and single step exception hooks Sandeepa Prabhu 2013-12-04 5:50 ` Sandeepa Prabhu 2013-12-04 5:50 ` [PATCH v4] arm64: support single-step and breakpoint handler hooks Sandeepa Prabhu 2013-12-04 5:50 ` Sandeepa Prabhu 2013-12-17 18:17 ` Catalin Marinas 2013-12-17 18:17 ` Catalin Marinas
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