/* * dwarf-regs.c : Mapping of DWARF debug register numbers into register names. * Extracted from probe-finder.c * * Written by Masami Hiramatsu * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * */ #include #include /* for EINVAL */ #include /* for strcmp */ #include /* for struct pt_regs */ #include /* for offsetof */ #include /* * See arch/x86/kernel/ptrace.c. * Different from it: * * - Since struct pt_regs is defined differently for user and kernel, * but we want to use 'ax, bx' instead of 'rax, rbx' (which is struct * field name of user's pt_regs), we make REG_OFFSET_NAME to accept * both string name and reg field name. * * - Since accessing x86_32's pt_regs from x86_64 building is difficult * and vise versa, we simply fill offset with -1, so * get_arch_regstr() still works but regs_query_register_offset() * returns error. * The only inconvenience caused by it now is that we are not allowed * to generate BPF prologue for a x86_64 kernel if perf is built for * x86_32. This is really a rare usecase. * * - Order is different from kernel's ptrace.c for get_arch_regstr(). Use * the order defined by dwarf. */ struct pt_regs_offset { const char *name; int offset; }; #define REG_OFFSET_END {.name = NULL, .offset = 0} #ifdef __x86_64__ # define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} # define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = -1} #else # define REG_OFFSET_NAME_64(n, r) {.name = n, .offset = -1} # define REG_OFFSET_NAME_32(n, r) {.name = n, .offset = offsetof(struct pt_regs, r)} #endif /* TODO: switching by dwarf address size */ #ifndef __x86_64__ static const struct pt_regs_offset x86_32_regoffset_table[] = { REG_OFFSET_NAME_32("%ax", eax), REG_OFFSET_NAME_32("%cx", ecx), REG_OFFSET_NAME_32("%dx", edx), REG_OFFSET_NAME_32("%bx", ebx), REG_OFFSET_NAME_32("$stack", esp), /* Stack address instead of %sp */ REG_OFFSET_NAME_32("%bp", ebp), REG_OFFSET_NAME_32("%si", esi), REG_OFFSET_NAME_32("%di", edi), REG_OFFSET_END, }; #define regoffset_table x86_32_regoffset_table #else static const struct pt_regs_offset x86_64_regoffset_table[] = { REG_OFFSET_NAME_64("%ax", rax), REG_OFFSET_NAME_64("%dx", rdx), REG_OFFSET_NAME_64("%cx", rcx), REG_OFFSET_NAME_64("%bx", rbx), REG_OFFSET_NAME_64("%si", rsi), REG_OFFSET_NAME_64("%di", rdi), REG_OFFSET_NAME_64("%bp", rbp), REG_OFFSET_NAME_64("%sp", rsp), REG_OFFSET_NAME_64("%r8", r8), REG_OFFSET_NAME_64("%r9", r9), REG_OFFSET_NAME_64("%r10", r10), REG_OFFSET_NAME_64("%r11", r11), REG_OFFSET_NAME_64("%r12", r12), REG_OFFSET_NAME_64("%r13", r13), REG_OFFSET_NAME_64("%r14", r14), REG_OFFSET_NAME_64("%r15", r15), REG_OFFSET_END, }; #define regoffset_table x86_64_regoffset_table #endif /* Minus 1 for the ending REG_OFFSET_END */ #define ARCH_MAX_REGS ((sizeof(regoffset_table) / sizeof(regoffset_table[0])) - 1) /* Return architecture dependent register string (for kprobe-tracer) */ const char *get_arch_regstr(unsigned int n) { return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL; } /* Reuse code from arch/x86/kernel/ptrace.c */ /** * regs_query_register_offset() - query register offset from its name * @name: the name of a register * * regs_query_register_offset() returns the offset of a register in struct * pt_regs from its name. If the name is invalid, this returns -EINVAL; */ int regs_query_register_offset(const char *name) { const struct pt_regs_offset *roff; for (roff = regoffset_table; roff->name != NULL; roff++) if (!strcmp(roff->name, name)) return roff->offset; return -EINVAL; } '35'>35space:mode:
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /sound/usb/line6/podhd.c
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'sound/usb/line6/podhd.c')