From 73266fc1df2f94cf72b3beba3eee3b88ed0b0664 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 22 Apr 2010 05:05:45 +0200 Subject: hw-breakpoints: Tag ptrace breakpoint as exclude_kernel Tag ptrace breakpoints with the exclude_kernel attribute set. This will make it easier to set generic policies on breakpoints, when it comes to ensure nobody unpriviliged try to breakpoint on the kernel. Signed-off-by: Frederic Weisbecker Acked-by: Paul Mundt Cc: Will Deacon Cc: Mahesh Salgaonkar Cc: K. Prasad Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Ingo Molnar --- include/linux/hw_breakpoint.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux/hw_breakpoint.h') diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index c70d27af03f9..a0aa5a9cfb0e 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -34,6 +34,12 @@ static inline void hw_breakpoint_init(struct perf_event_attr *attr) attr->sample_period = 1; } +static inline void ptrace_breakpoint_init(struct perf_event_attr *attr) +{ + hw_breakpoint_init(attr); + attr->exclude_kernel = 1; +} + static inline unsigned long hw_breakpoint_addr(struct perf_event *bp) { return bp->attr.bp_addr; -- cgit v1.2.3 From 0102752e4c9e0655b39734550d4c35327954f7f9 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sun, 11 Apr 2010 18:55:56 +0200 Subject: hw-breakpoints: Separate constraint space for data and instruction breakpoints There are two outstanding fashions for archs to implement hardware breakpoints. The first is to separate breakpoint address pattern definition space between data and instruction breakpoints. We then have typically distinct instruction address breakpoint registers and data address breakpoint registers, delivered with separate control registers for data and instruction breakpoints as well. This is the case of PowerPc and ARM for example. The second consists in having merged breakpoint address space definition between data and instruction breakpoint. Address registers can host either instruction or data address and the access mode for the breakpoint is defined in a control register. This is the case of x86 and Super H. This patch adds a new CONFIG_HAVE_MIXED_BREAKPOINTS_REGS config that archs can select if they belong to the second case. Those will have their slot allocation merged for instructions and data breakpoints. The others will have a separate slot tracking between data and instruction breakpoints. Signed-off-by: Frederic Weisbecker Acked-by: Paul Mundt Cc: Will Deacon Cc: Mahesh Salgaonkar Cc: K. Prasad Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Ingo Molnar --- arch/Kconfig | 11 ++++++ arch/sh/Kconfig | 1 + arch/x86/Kconfig | 1 + include/linux/hw_breakpoint.h | 9 +++-- kernel/hw_breakpoint.c | 86 +++++++++++++++++++++++++++++-------------- 5 files changed, 78 insertions(+), 30 deletions(-) (limited to 'include/linux/hw_breakpoint.h') diff --git a/arch/Kconfig b/arch/Kconfig index f06010fb4838..acda512da2e2 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -137,6 +137,17 @@ config HAVE_HW_BREAKPOINT bool depends on PERF_EVENTS +config HAVE_MIXED_BREAKPOINTS_REGS + bool + depends on HAVE_HW_BREAKPOINT + help + Depending on the arch implementation of hardware breakpoints, + some of them have separate registers for data and instruction + breakpoints addresses, others have mixed registers to store + them but define the access type in a control register. + Select this option if your arch implements breakpoints under the + latter fashion. + config HAVE_USER_RETURN_NOTIFIER bool diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index 8d90564c2bcf..e6d8ab5cfa9d 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -44,6 +44,7 @@ config SUPERH32 select HAVE_FUNCTION_GRAPH_TRACER select HAVE_ARCH_KGDB select HAVE_HW_BREAKPOINT + select HAVE_MIXED_BREAKPOINTS_REGS select PERF_EVENTS if HAVE_HW_BREAKPOINT select ARCH_HIBERNATION_POSSIBLE if MMU diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 97a95dfd1181..01177dcbe261 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -53,6 +53,7 @@ config X86 select HAVE_KERNEL_LZMA select HAVE_KERNEL_LZO select HAVE_HW_BREAKPOINT + select HAVE_MIXED_BREAKPOINTS_REGS select PERF_EVENTS select ANON_INODES select HAVE_ARCH_KMEMCHECK diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index a0aa5a9cfb0e..7e8899093098 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -9,9 +9,12 @@ enum { }; enum { - HW_BREAKPOINT_R = 1, - HW_BREAKPOINT_W = 2, - HW_BREAKPOINT_X = 4, + HW_BREAKPOINT_EMPTY = 0, + HW_BREAKPOINT_R = 1, + HW_BREAKPOINT_W = 2, + HW_BREAKPOINT_RW = HW_BREAKPOINT_R | HW_BREAKPOINT_W, + HW_BREAKPOINT_X = 4, + HW_BREAKPOINT_INVALID = HW_BREAKPOINT_RW | HW_BREAKPOINT_X, }; #ifdef __KERNEL__ diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index 89e8a050c43a..8ead1345e33b 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -45,18 +45,28 @@ #include +enum bp_type_idx { + TYPE_INST = 0, +#ifdef CONFIG_HAVE_MIXED_BREAKPOINTS_REGS + TYPE_DATA = 0, +#else + TYPE_DATA = 1, +#endif + TYPE_MAX +}; + /* * Constraints data */ /* Number of pinned cpu breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned); +static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]); /* Number of pinned task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[HBP_NUM]); +static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[TYPE_MAX][HBP_NUM]); /* Number of non-pinned cpu/task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_bp_flexible); +static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]); /* Gather the number of total pinned and un-pinned bp in a cpuset */ struct bp_busy_slots { @@ -67,14 +77,22 @@ struct bp_busy_slots { /* Serialize accesses to the above constraints */ static DEFINE_MUTEX(nr_bp_mutex); +static inline enum bp_type_idx find_slot_idx(struct perf_event *bp) +{ + if (bp->attr.bp_type & HW_BREAKPOINT_RW) + return TYPE_DATA; + + return TYPE_INST; +} + /* * Report the maximum number of pinned breakpoints a task * have in this cpu */ -static unsigned int max_task_bp_pinned(int cpu) +static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) { int i; - unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); + unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); for (i = HBP_NUM -1; i >= 0; i--) { if (tsk_pinned[i] > 0) @@ -84,7 +102,7 @@ static unsigned int max_task_bp_pinned(int cpu) return 0; } -static int task_bp_pinned(struct task_struct *tsk) +static int task_bp_pinned(struct task_struct *tsk, enum bp_type_idx type) { struct perf_event_context *ctx = tsk->perf_event_ctxp; struct list_head *list; @@ -105,7 +123,8 @@ static int task_bp_pinned(struct task_struct *tsk) */ list_for_each_entry(bp, list, event_entry) { if (bp->attr.type == PERF_TYPE_BREAKPOINT) - count++; + if (find_slot_idx(bp) == type) + count++; } raw_spin_unlock_irqrestore(&ctx->lock, flags); @@ -118,18 +137,19 @@ static int task_bp_pinned(struct task_struct *tsk) * a given cpu (cpu > -1) or in all of them (cpu = -1). */ static void -fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) +fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp, + enum bp_type_idx type) { int cpu = bp->cpu; struct task_struct *tsk = bp->ctx->task; if (cpu >= 0) { - slots->pinned = per_cpu(nr_cpu_bp_pinned, cpu); + slots->pinned = per_cpu(nr_cpu_bp_pinned[type], cpu); if (!tsk) - slots->pinned += max_task_bp_pinned(cpu); + slots->pinned += max_task_bp_pinned(cpu, type); else - slots->pinned += task_bp_pinned(tsk); - slots->flexible = per_cpu(nr_bp_flexible, cpu); + slots->pinned += task_bp_pinned(tsk, type); + slots->flexible = per_cpu(nr_bp_flexible[type], cpu); return; } @@ -137,16 +157,16 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) for_each_online_cpu(cpu) { unsigned int nr; - nr = per_cpu(nr_cpu_bp_pinned, cpu); + nr = per_cpu(nr_cpu_bp_pinned[type], cpu); if (!tsk) - nr += max_task_bp_pinned(cpu); + nr += max_task_bp_pinned(cpu, type); else - nr += task_bp_pinned(tsk); + nr += task_bp_pinned(tsk, type); if (nr > slots->pinned) slots->pinned = nr; - nr = per_cpu(nr_bp_flexible, cpu); + nr = per_cpu(nr_bp_flexible[type], cpu); if (nr > slots->flexible) slots->flexible = nr; @@ -156,14 +176,15 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp) /* * Add a pinned breakpoint for the given task in our constraint table */ -static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable) +static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable, + enum bp_type_idx type) { unsigned int *tsk_pinned; int count = 0; - count = task_bp_pinned(tsk); + count = task_bp_pinned(tsk, type); - tsk_pinned = per_cpu(nr_task_bp_pinned, cpu); + tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); if (enable) { tsk_pinned[count]++; if (count > 0) @@ -178,7 +199,8 @@ static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable) /* * Add/remove the given breakpoint in our constraint table */ -static void toggle_bp_slot(struct perf_event *bp, bool enable) +static void +toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type) { int cpu = bp->cpu; struct task_struct *tsk = bp->ctx->task; @@ -186,20 +208,20 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) /* Pinned counter task profiling */ if (tsk) { if (cpu >= 0) { - toggle_bp_task_slot(tsk, cpu, enable); + toggle_bp_task_slot(tsk, cpu, enable, type); return; } for_each_online_cpu(cpu) - toggle_bp_task_slot(tsk, cpu, enable); + toggle_bp_task_slot(tsk, cpu, enable, type); return; } /* Pinned counter cpu profiling */ if (enable) - per_cpu(nr_cpu_bp_pinned, bp->cpu)++; + per_cpu(nr_cpu_bp_pinned[type], bp->cpu)++; else - per_cpu(nr_cpu_bp_pinned, bp->cpu)--; + per_cpu(nr_cpu_bp_pinned[type], bp->cpu)--; } /* @@ -246,14 +268,21 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable) static int __reserve_bp_slot(struct perf_event *bp) { struct bp_busy_slots slots = {0}; + enum bp_type_idx type; - fetch_bp_busy_slots(&slots, bp); + /* Basic checks */ + if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY || + bp->attr.bp_type == HW_BREAKPOINT_INVALID) + return -EINVAL; + + type = find_slot_idx(bp); + fetch_bp_busy_slots(&slots, bp, type); /* Flexible counters need to keep at least one slot */ if (slots.pinned + (!!slots.flexible) == HBP_NUM) return -ENOSPC; - toggle_bp_slot(bp, true); + toggle_bp_slot(bp, true, type); return 0; } @@ -273,7 +302,10 @@ int reserve_bp_slot(struct perf_event *bp) static void __release_bp_slot(struct perf_event *bp) { - toggle_bp_slot(bp, false); + enum bp_type_idx type; + + type = find_slot_idx(bp); + toggle_bp_slot(bp, false, type); } void release_bp_slot(struct perf_event *bp) -- cgit v1.2.3 From feef47d0cb530e8419dfa0b48141b538b89b1b1a Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 23 Apr 2010 05:59:55 +0200 Subject: hw-breakpoints: Get the number of available registers on boot dynamically The breakpoint generic layer assumes that archs always know in advance the static number of address registers available to host breakpoints through the HBP_NUM macro. However this is not true for every archs. For example Arm needs to get this information dynamically to handle the compatiblity between different versions. To solve this, this patch proposes to drop the static HBP_NUM macro and let the arch provide the number of available slots through a new hw_breakpoint_slots() function. For archs that have CONFIG_HAVE_MIXED_BREAKPOINTS_REGS selected, it will be called once as the number of registers fits for instruction and data breakpoints together. For the others it will be called first to get the number of instruction breakpoint registers and another time to get the data breakpoint registers, the targeted type is given as a parameter of hw_breakpoint_slots(). Reported-by: Will Deacon Signed-off-by: Frederic Weisbecker Acked-by: Paul Mundt Cc: Mahesh Salgaonkar Cc: K. Prasad Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Jason Wessel Cc: Ingo Molnar --- arch/sh/include/asm/hw_breakpoint.h | 5 ++++ arch/x86/include/asm/hw_breakpoint.h | 5 ++++ include/linux/hw_breakpoint.h | 10 +++++++ kernel/hw_breakpoint.c | 53 ++++++++++++++++++++++++++++-------- kernel/trace/trace_ksym.c | 26 +++++------------- 5 files changed, 68 insertions(+), 31 deletions(-) (limited to 'include/linux/hw_breakpoint.h') diff --git a/arch/sh/include/asm/hw_breakpoint.h b/arch/sh/include/asm/hw_breakpoint.h index 382bad937dcc..e14cad96798f 100644 --- a/arch/sh/include/asm/hw_breakpoint.h +++ b/arch/sh/include/asm/hw_breakpoint.h @@ -46,6 +46,11 @@ struct pmu; /* Maximum number of UBC channels */ #define HBP_NUM 2 +static inline int hw_breakpoint_slots(int type) +{ + return HBP_NUM; +} + /* arch/sh/kernel/hw_breakpoint.c */ extern int arch_check_bp_in_kernelspace(struct perf_event *bp); extern int arch_validate_hwbkpt_settings(struct perf_event *bp); diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h index c77a5a6fab9d..942255310e6a 100644 --- a/arch/x86/include/asm/hw_breakpoint.h +++ b/arch/x86/include/asm/hw_breakpoint.h @@ -41,6 +41,11 @@ struct arch_hw_breakpoint { /* Total number of available HW breakpoint registers */ #define HBP_NUM 4 +static inline int hw_breakpoint_slots(int type) +{ + return HBP_NUM; +} + struct perf_event; struct pmu; diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h index 7e8899093098..a2d6ea49ec56 100644 --- a/include/linux/hw_breakpoint.h +++ b/include/linux/hw_breakpoint.h @@ -17,6 +17,16 @@ enum { HW_BREAKPOINT_INVALID = HW_BREAKPOINT_RW | HW_BREAKPOINT_X, }; +enum bp_type_idx { + TYPE_INST = 0, +#ifdef CONFIG_HAVE_MIXED_BREAKPOINTS_REGS + TYPE_DATA = 0, +#else + TYPE_DATA = 1, +#endif + TYPE_MAX +}; + #ifdef __KERNEL__ #include diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c index 974498b858fc..684b710cbb91 100644 --- a/kernel/hw_breakpoint.c +++ b/kernel/hw_breakpoint.c @@ -40,20 +40,12 @@ #include #include #include +#include #include #include #include -enum bp_type_idx { - TYPE_INST = 0, -#ifdef CONFIG_HAVE_MIXED_BREAKPOINTS_REGS - TYPE_DATA = 0, -#else - TYPE_DATA = 1, -#endif - TYPE_MAX -}; /* * Constraints data @@ -63,11 +55,15 @@ enum bp_type_idx { static DEFINE_PER_CPU(unsigned int, nr_cpu_bp_pinned[TYPE_MAX]); /* Number of pinned task breakpoints in a cpu */ -static DEFINE_PER_CPU(unsigned int, nr_task_bp_pinned[TYPE_MAX][HBP_NUM]); +static DEFINE_PER_CPU(unsigned int, *nr_task_bp_pinned[TYPE_MAX]); /* Number of non-pinned cpu/task breakpoints in a cpu */ static DEFINE_PER_CPU(unsigned int, nr_bp_flexible[TYPE_MAX]); +static int nr_slots[TYPE_MAX]; + +static int constraints_initialized; + /* Gather the number of total pinned and un-pinned bp in a cpuset */ struct bp_busy_slots { unsigned int pinned; @@ -99,7 +95,7 @@ static unsigned int max_task_bp_pinned(int cpu, enum bp_type_idx type) int i; unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu); - for (i = HBP_NUM -1; i >= 0; i--) { + for (i = nr_slots[type] - 1; i >= 0; i--) { if (tsk_pinned[i] > 0) return i + 1; } @@ -292,6 +288,10 @@ static int __reserve_bp_slot(struct perf_event *bp) enum bp_type_idx type; int weight; + /* We couldn't initialize breakpoint constraints on boot */ + if (!constraints_initialized) + return -ENOMEM; + /* Basic checks */ if (bp->attr.bp_type == HW_BREAKPOINT_EMPTY || bp->attr.bp_type == HW_BREAKPOINT_INVALID) @@ -304,7 +304,7 @@ static int __reserve_bp_slot(struct perf_event *bp) fetch_this_slot(&slots, weight); /* Flexible counters need to keep at least one slot */ - if (slots.pinned + (!!slots.flexible) > HBP_NUM) + if (slots.pinned + (!!slots.flexible) > nr_slots[type]) return -ENOSPC; toggle_bp_slot(bp, true, type, weight); @@ -551,7 +551,36 @@ static struct notifier_block hw_breakpoint_exceptions_nb = { static int __init init_hw_breakpoint(void) { + unsigned int **task_bp_pinned; + int cpu, err_cpu; + int i; + + for (i = 0; i < TYPE_MAX; i++) + nr_slots[i] = hw_breakpoint_slots(i); + + for_each_possible_cpu(cpu) { + for (i = 0; i < TYPE_MAX; i++) { + task_bp_pinned = &per_cpu(nr_task_bp_pinned[i], cpu); + *task_bp_pinned = kzalloc(sizeof(int) * nr_slots[i], + GFP_KERNEL); + if (!*task_bp_pinned) + goto err_alloc; + } + } + + constraints_initialized = 1; + return register_die_notifier(&hw_breakpoint_exceptions_nb); + + err_alloc: + for_each_possible_cpu(err_cpu) { + if (err_cpu == cpu) + break; + for (i = 0; i < TYPE_MAX; i++) + kfree(per_cpu(nr_task_bp_pinned[i], cpu)); + } + + return -ENOMEM; } core_initcall(init_hw_breakpoint); diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c index d59cd6879477..8eaf00749b65 100644 --- a/kernel/trace/trace_ksym.c +++ b/kernel/trace/trace_ksym.c @@ -34,12 +34,6 @@ #include -/* - * For now, let us restrict the no. of symbols traced simultaneously to number - * of available hardware breakpoint registers. - */ -#define KSYM_TRACER_MAX HBP_NUM - #define KSYM_TRACER_OP_LEN 3 /* rw- */ struct trace_ksym { @@ -53,7 +47,6 @@ struct trace_ksym { static struct trace_array *ksym_trace_array; -static unsigned int ksym_filter_entry_count; static unsigned int ksym_tracing_enabled; static HLIST_HEAD(ksym_filter_head); @@ -181,13 +174,6 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) struct trace_ksym *entry; int ret = -ENOMEM; - if (ksym_filter_entry_count >= KSYM_TRACER_MAX) { - printk(KERN_ERR "ksym_tracer: Maximum limit:(%d) reached. No" - " new requests for tracing can be accepted now.\n", - KSYM_TRACER_MAX); - return -ENOSPC; - } - entry = kzalloc(sizeof(struct trace_ksym), GFP_KERNEL); if (!entry) return -ENOMEM; @@ -203,13 +189,17 @@ int process_new_ksym_entry(char *ksymname, int op, unsigned long addr) if (IS_ERR(entry->ksym_hbp)) { ret = PTR_ERR(entry->ksym_hbp); - printk(KERN_INFO "ksym_tracer request failed. Try again" - " later!!\n"); + if (ret == -ENOSPC) { + printk(KERN_ERR "ksym_tracer: Maximum limit reached." + " No new requests for tracing can be accepted now.\n"); + } else { + printk(KERN_INFO "ksym_tracer request failed. Try again" + " later!!\n"); + } goto err; } hlist_add_head_rcu(&(entry->ksym_hlist), &ksym_filter_head); - ksym_filter_entry_count++; return 0; @@ -265,7 +255,6 @@ static void __ksym_trace_reset(void) hlist_for_each_entry_safe(entry, node, node1, &ksym_filter_head, ksym_hlist) { unregister_wide_hw_breakpoint(entry->ksym_hbp); - ksym_filter_entry_count--; hlist_del_rcu(&(entry->ksym_hlist)); synchronize_rcu(); kfree(entry); @@ -338,7 +327,6 @@ static ssize_t ksym_trace_filter_write(struct file *file, goto out_unlock; } /* Error or "symbol:---" case: drop it */ - ksym_filter_entry_count--; hlist_del_rcu(&(entry->ksym_hlist)); synchronize_rcu(); kfree(entry); -- cgit v1.2.3