diff options
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 49 |
1 files changed, 39 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 6d5e7cfd97e7..e8c68a5091df 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -19,6 +19,7 @@ #include <linux/kdebug.h> #include <linux/sched.h> #include <linux/uaccess.h> +#include <linux/highmem.h> #include <asm/apic.h> #include <asm/stacktrace.h> @@ -1617,20 +1618,48 @@ perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry) entry->kernel = entry->nr - nr; } -static int copy_stack_frame(const void __user *fp, struct stack_frame *frame) +/* + * best effort, GUP based copy_from_user() that assumes IRQ or NMI context + */ +static unsigned long +copy_from_user_nmi(void *to, const void __user *from, unsigned long n) { + unsigned long offset, addr = (unsigned long)from; + int type = in_nmi() ? KM_NMI : KM_IRQ0; + unsigned long size, len = 0; + struct page *page; + void *map; int ret; - if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) - return 0; + do { + ret = __get_user_pages_fast(addr, 1, 0, &page); + if (!ret) + break; - ret = 1; - pagefault_disable(); - if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) - ret = 0; - pagefault_enable(); + offset = addr & (PAGE_SIZE - 1); + size = min(PAGE_SIZE - offset, n - len); - return ret; + map = kmap_atomic(page, type); + memcpy(to, map+offset, size); + kunmap_atomic(map, type); + put_page(page); + + len += size; + to += size; + addr += size; + + } while (len < n); + + return len; +} + +static int copy_stack_frame(const void __user *fp, struct stack_frame *frame) +{ + unsigned long bytes; + + bytes = copy_from_user_nmi(frame, fp, sizeof(*frame)); + + return bytes == sizeof(*frame); } static void @@ -1643,7 +1672,7 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry) if (!user_mode(regs)) regs = task_pt_regs(current); - fp = (void __user *)regs->bp; + fp = (void __user *)regs->bp; callchain_store(entry, regs->ip); |