From: Peter Zijlstra Date: Fri, 12 Jun 2009 10:46:55 +0000 (+0200) Subject: perf_counter: Add forward/backward attribute ABI compatibility X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=974802eaa1afdc87e00821df7020a2b3c6fee623;p=linux-beck.git perf_counter: Add forward/backward attribute ABI compatibility Provide for means of extending the perf_counter_attr in a 'natural' way. We allow growing the structure by appending fields at the end by specifying the full structure size inside it. When a new kernel sees a smaller (old) structure, it will 0 pad the tail. When an old kernel sees a larger (new) structure, it will verify the tail consists of 0s, otherwise fail. If we fail due to a size-mismatch, we return -E2BIG and write the kernel's native attribe size back into the provided structure. Furthermore, add some attribute verification, so that we'll fail counter creation when unknown bits are present (PERF_SAMPLE, PERF_FORMAT, or in the __reserved fields). (This ABI detail is introduced while keeping the existing syscall ABI.) Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo LKML-Reference: Signed-off-by: Ingo Molnar --- diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 7c4f32f6ae1a..1b3118a1023a 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -120,6 +120,8 @@ enum perf_counter_sample_format { PERF_SAMPLE_ID = 1U << 6, PERF_SAMPLE_CPU = 1U << 7, PERF_SAMPLE_PERIOD = 1U << 8, + + PERF_SAMPLE_MAX = 1U << 9, /* non-ABI */ }; /* @@ -131,17 +133,26 @@ enum perf_counter_read_format { PERF_FORMAT_TOTAL_TIME_ENABLED = 1U << 0, PERF_FORMAT_TOTAL_TIME_RUNNING = 1U << 1, PERF_FORMAT_ID = 1U << 2, + + PERF_FORMAT_MAX = 1U << 3, /* non-ABI */ }; +#define PERF_ATTR_SIZE_VER0 64 /* sizeof first published struct */ + /* * Hardware event to monitor via a performance monitoring counter: */ struct perf_counter_attr { + /* * Major type: hardware/software/tracepoint/etc. */ __u32 type; - __u32 __reserved_1; + + /* + * Size of the attr structure, for fwd/bwd compat. + */ + __u32 size; /* * Type specific configuration information. @@ -168,12 +179,12 @@ struct perf_counter_attr { comm : 1, /* include comm data */ freq : 1, /* use freq, not period */ - __reserved_2 : 53; + __reserved_1 : 53; __u32 wakeup_events; /* wakeup every n events */ - __u32 __reserved_3; + __u32 __reserved_2; - __u64 __reserved_4; + __u64 __reserved_3; }; /* diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index c6c84ad8bd71..418d90f5effe 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -758,6 +758,6 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[]); asmlinkage long sys_perf_counter_open( - const struct perf_counter_attr __user *attr_uptr, + struct perf_counter_attr __user *attr_uptr, pid_t pid, int cpu, int group_fd, unsigned long flags); #endif diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 663bbe015057..29b685f551aa 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -3584,6 +3584,9 @@ perf_counter_alloc(struct perf_counter_attr *attr, case PERF_TYPE_TRACEPOINT: pmu = tp_perf_counter_init(counter); break; + + default: + break; } done: err = 0; @@ -3610,6 +3613,85 @@ done: return counter; } +static int perf_copy_attr(struct perf_counter_attr __user *uattr, + struct perf_counter_attr *attr) +{ + int ret; + u32 size; + + if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0)) + return -EFAULT; + + /* + * zero the full structure, so that a short copy will be nice. + */ + memset(attr, 0, sizeof(*attr)); + + ret = get_user(size, &uattr->size); + if (ret) + return ret; + + if (size > PAGE_SIZE) /* silly large */ + goto err_size; + + if (!size) /* abi compat */ + size = PERF_ATTR_SIZE_VER0; + + if (size < PERF_ATTR_SIZE_VER0) + goto err_size; + + /* + * If we're handed a bigger struct than we know of, + * ensure all the unknown bits are 0. + */ + if (size > sizeof(*attr)) { + unsigned long val; + unsigned long __user *addr; + unsigned long __user *end; + + addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr), + sizeof(unsigned long)); + end = PTR_ALIGN((void __user *)uattr + size, + sizeof(unsigned long)); + + for (; addr < end; addr += sizeof(unsigned long)) { + ret = get_user(val, addr); + if (ret) + return ret; + if (val) + goto err_size; + } + } + + ret = copy_from_user(attr, uattr, size); + if (ret) + return -EFAULT; + + /* + * If the type exists, the corresponding creation will verify + * the attr->config. + */ + if (attr->type >= PERF_TYPE_MAX) + return -EINVAL; + + if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3) + return -EINVAL; + + if (attr->sample_type & ~(PERF_SAMPLE_MAX-1)) + return -EINVAL; + + if (attr->read_format & ~(PERF_FORMAT_MAX-1)) + return -EINVAL; + +out: + return ret; + +err_size: + put_user(sizeof(*attr), &uattr->size); + ret = -E2BIG; + goto out; +} + /** * sys_perf_counter_open - open a performance counter, associate it to a task/cpu * @@ -3619,7 +3701,7 @@ done: * @group_fd: group leader counter fd */ SYSCALL_DEFINE5(perf_counter_open, - const struct perf_counter_attr __user *, attr_uptr, + struct perf_counter_attr __user *, attr_uptr, pid_t, pid, int, cpu, int, group_fd, unsigned long, flags) { struct perf_counter *counter, *group_leader; @@ -3635,8 +3717,9 @@ SYSCALL_DEFINE5(perf_counter_open, if (flags) return -EINVAL; - if (copy_from_user(&attr, attr_uptr, sizeof(attr)) != 0) - return -EFAULT; + ret = perf_copy_attr(attr_uptr, &attr); + if (ret) + return ret; if (!attr.exclude_kernel) { if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) diff --git a/tools/perf/perf.h b/tools/perf/perf.h index af0a5046d743..87a1aca4a424 100644 --- a/tools/perf/perf.h +++ b/tools/perf/perf.h @@ -53,11 +53,12 @@ static inline unsigned long long rdclock(void) _min1 < _min2 ? _min1 : _min2; }) static inline int -sys_perf_counter_open(struct perf_counter_attr *attr_uptr, +sys_perf_counter_open(struct perf_counter_attr *attr, pid_t pid, int cpu, int group_fd, unsigned long flags) { - return syscall(__NR_perf_counter_open, attr_uptr, pid, cpu, + attr->size = sizeof(*attr); + return syscall(__NR_perf_counter_open, attr, pid, cpu, group_fd, flags); }