From a0e3e70243f5b270bc3eca718f0a9fa5e6b8262e Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Fri, 3 Jun 2011 16:37:47 +0200 Subject: [PATCH] oprofile, x86: Fix nmi-unsafe callgraph support Current oprofile's x86 callgraph support may trigger page faults throwing the BUG_ON(in_nmi()) message below. This patch fixes this by using the same nmi-safe copy-from-user code as in perf. ------------[ cut here ]------------ kernel BUG at .../arch/x86/kernel/traps.c:436! invalid opcode: 0000 [#1] SMP last sysfs file: /sys/devices/pci0000:00/0000:00:0a.0/0000:07:00.0/0000:08:04.0/net/eth0/broadcast CPU 5 Modules linked in: Pid: 8611, comm: opcontrol Not tainted 2.6.39-00007-gfe47ae7 #1 Advanced Micro Device Anaheim/Anaheim RIP: 0010:[] [] do_nmi+0x22/0x1ee RSP: 0000:ffff88042fd47f28 EFLAGS: 00010002 RAX: ffff88042c0a7fd8 RBX: 0000000000000001 RCX: 00000000c0000101 RDX: 00000000ffff8804 RSI: ffffffffffffffff RDI: ffff88042fd47f58 RBP: ffff88042fd47f48 R08: 0000000000000004 R09: 0000000000001484 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88042fd47f58 R13: 0000000000000000 R14: ffff88042fd47d98 R15: 0000000000000020 FS: 00007fca25e56700(0000) GS:ffff88042fd40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000074 CR3: 000000042d28b000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process opcontrol (pid: 8611, threadinfo ffff88042c0a6000, task ffff88042c532310) Stack: 0000000000000000 0000000000000001 ffff88042c0a7fd8 0000000000000000 ffff88042fd47de8 ffffffff813e897a 0000000000000020 ffff88042fd47d98 0000000000000000 ffff88042c0a7fd8 ffff88042fd47de8 0000000000000074 Call Trace: [] nmi+0x1a/0x20 [] ? bad_to_user+0x25/0x771 <> Code: ff 59 5b 41 5c 41 5d c9 c3 55 65 48 8b 04 25 88 b5 00 00 48 89 e5 41 55 41 54 49 89 fc 53 48 83 ec 08 f6 80 47 e0 ff ff 04 74 04 <0f> 0b eb fe 81 80 44 e0 ff ff 00 00 01 04 65 ff 04 25 c4 0f 01 RIP [] do_nmi+0x22/0x1ee RSP ---[ end trace ed6752185092104b ]--- Kernel panic - not syncing: Fatal exception in interrupt Pid: 8611, comm: opcontrol Tainted: G D 2.6.39-00007-gfe47ae7 #1 Call Trace: [] panic+0x8c/0x188 [] oops_end+0x81/0x8e [] die+0x55/0x5e [] do_trap+0x11c/0x12b [] do_invalid_op+0x91/0x9a [] ? do_nmi+0x22/0x1ee [] ? oprofile_add_sample+0x83/0x95 [] ? op_amd_check_ctrs+0x4f/0x2cf [] invalid_op+0x15/0x20 [] ? do_nmi+0x22/0x1ee [] ? do_nmi+0x67/0x1ee [] nmi+0x1a/0x20 [] ? bad_to_user+0x25/0x771 <> Cc: John Lumby Cc: Maynard Johnson Cc: # .37+ Signed-off-by: Robert Richter --- arch/x86/oprofile/backtrace.c | 56 +++++++++++++++++++++++++++++------ 1 file changed, 47 insertions(+), 9 deletions(-) diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c index a5b64ab4cd6e..32f78eb46744 100644 --- a/arch/x86/oprofile/backtrace.c +++ b/arch/x86/oprofile/backtrace.c @@ -11,10 +11,12 @@ #include #include #include +#include +#include + #include #include #include -#include static int backtrace_stack(void *data, char *name) { @@ -36,17 +38,53 @@ static struct stacktrace_ops backtrace_ops = { .walk_stack = print_context_stack, }; +/* from arch/x86/kernel/cpu/perf_event.c: */ + +/* + * 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; + unsigned long size, len = 0; + struct page *page; + void *map; + int ret; + + do { + ret = __get_user_pages_fast(addr, 1, 0, &page); + if (!ret) + break; + + offset = addr & (PAGE_SIZE - 1); + size = min(PAGE_SIZE - offset, n - len); + + map = kmap_atomic(page); + memcpy(to, map+offset, size); + kunmap_atomic(map); + put_page(page); + + len += size; + to += size; + addr += size; + + } while (len < n); + + return len; +} + #ifdef CONFIG_COMPAT static struct stack_frame_ia32 * dump_user_backtrace_32(struct stack_frame_ia32 *head) { + /* Also check accessibility of one struct frame_head beyond: */ struct stack_frame_ia32 bufhead[2]; struct stack_frame_ia32 *fp; + unsigned long bytes; - /* Also check accessibility of one struct frame_head beyond */ - if (!access_ok(VERIFY_READ, head, sizeof(bufhead))) - return NULL; - if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead))) + bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead)); + if (bytes != sizeof(bufhead)) return NULL; fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame); @@ -87,12 +125,12 @@ x86_backtrace_32(struct pt_regs * const regs, unsigned int depth) static struct stack_frame *dump_user_backtrace(struct stack_frame *head) { + /* Also check accessibility of one struct frame_head beyond: */ struct stack_frame bufhead[2]; + unsigned long bytes; - /* Also check accessibility of one struct stack_frame beyond */ - if (!access_ok(VERIFY_READ, head, sizeof(bufhead))) - return NULL; - if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead))) + bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead)); + if (bytes != sizeof(bufhead)) return NULL; oprofile_add_trace(bufhead[0].return_address);