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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-12 06:46:55 -0400
committerIngo Molnar <mingo@elte.hu>2009-06-12 08:28:52 -0400
commit974802eaa1afdc87e00821df7020a2b3c6fee623 (patch)
treeb5c38bece7f4948fe9d5cf9be02a0042e0fa39f6 /kernel/perf_counter.c
parentbbd36e5e6aa6f1757c84cdb406b6eb81686d14af (diff)
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 <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
-rw-r--r--kernel/perf_counter.c89
1 files changed, 86 insertions, 3 deletions
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,
3584 case PERF_TYPE_TRACEPOINT: 3584 case PERF_TYPE_TRACEPOINT:
3585 pmu = tp_perf_counter_init(counter); 3585 pmu = tp_perf_counter_init(counter);
3586 break; 3586 break;
3587
3588 default:
3589 break;
3587 } 3590 }
3588done: 3591done:
3589 err = 0; 3592 err = 0;
@@ -3610,6 +3613,85 @@ done:
3610 return counter; 3613 return counter;
3611} 3614}
3612 3615
3616static int perf_copy_attr(struct perf_counter_attr __user *uattr,
3617 struct perf_counter_attr *attr)
3618{
3619 int ret;
3620 u32 size;
3621
3622 if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0))
3623 return -EFAULT;
3624
3625 /*
3626 * zero the full structure, so that a short copy will be nice.
3627 */
3628 memset(attr, 0, sizeof(*attr));
3629
3630 ret = get_user(size, &uattr->size);
3631 if (ret)
3632 return ret;
3633
3634 if (size > PAGE_SIZE) /* silly large */
3635 goto err_size;
3636
3637 if (!size) /* abi compat */
3638 size = PERF_ATTR_SIZE_VER0;
3639
3640 if (size < PERF_ATTR_SIZE_VER0)
3641 goto err_size;
3642
3643 /*
3644 * If we're handed a bigger struct than we know of,
3645 * ensure all the unknown bits are 0.
3646 */
3647 if (size > sizeof(*attr)) {
3648 unsigned long val;
3649 unsigned long __user *addr;
3650 unsigned long __user *end;
3651
3652 addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr),
3653 sizeof(unsigned long));
3654 end = PTR_ALIGN((void __user *)uattr + size,
3655 sizeof(unsigned long));
3656
3657 for (; addr < end; addr += sizeof(unsigned long)) {
3658 ret = get_user(val, addr);
3659 if (ret)
3660 return ret;
3661 if (val)
3662 goto err_size;
3663 }
3664 }
3665
3666 ret = copy_from_user(attr, uattr, size);
3667 if (ret)
3668 return -EFAULT;
3669
3670 /*
3671 * If the type exists, the corresponding creation will verify
3672 * the attr->config.
3673 */
3674 if (attr->type >= PERF_TYPE_MAX)
3675 return -EINVAL;
3676
3677 if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3)
3678 return -EINVAL;
3679
3680 if (attr->sample_type & ~(PERF_SAMPLE_MAX-1))
3681 return -EINVAL;
3682
3683 if (attr->read_format & ~(PERF_FORMAT_MAX-1))
3684 return -EINVAL;
3685
3686out:
3687 return ret;
3688
3689err_size:
3690 put_user(sizeof(*attr), &uattr->size);
3691 ret = -E2BIG;
3692 goto out;
3693}
3694
3613/** 3695/**
3614 * sys_perf_counter_open - open a performance counter, associate it to a task/cpu 3696 * sys_perf_counter_open - open a performance counter, associate it to a task/cpu
3615 * 3697 *
@@ -3619,7 +3701,7 @@ done:
3619 * @group_fd: group leader counter fd 3701 * @group_fd: group leader counter fd
3620 */ 3702 */
3621SYSCALL_DEFINE5(perf_counter_open, 3703SYSCALL_DEFINE5(perf_counter_open,
3622 const struct perf_counter_attr __user *, attr_uptr, 3704 struct perf_counter_attr __user *, attr_uptr,
3623 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags) 3705 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
3624{ 3706{
3625 struct perf_counter *counter, *group_leader; 3707 struct perf_counter *counter, *group_leader;
@@ -3635,8 +3717,9 @@ SYSCALL_DEFINE5(perf_counter_open,
3635 if (flags) 3717 if (flags)
3636 return -EINVAL; 3718 return -EINVAL;
3637 3719
3638 if (copy_from_user(&attr, attr_uptr, sizeof(attr)) != 0) 3720 ret = perf_copy_attr(attr_uptr, &attr);
3639 return -EFAULT; 3721 if (ret)
3722 return ret;
3640 3723
3641 if (!attr.exclude_kernel) { 3724 if (!attr.exclude_kernel) {
3642 if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) 3725 if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))