| Message ID | 20160810054446.5624-1-cyrilbur@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
Cyril Bur <cyrilbur@gmail.com> writes: > There was an assumption that flush_tmregs_to_thread() would only be > called for a task which is not current. And a warning could be shown > to indicate that current is being ptraced. > > In the event of a core dump the current threads state is needed. This > means that flush_tmregs_to_thread() must do its best to flush even for > current. > > This patch also moves flush_tmregs_to_thread() into ptrace.c as it is > only called from that file. > > Signed-off-by: Cyril Bur <cyrilbur@gmail.com> I munged the change log a bunch: powerpc/ptrace: Fix coredump since ptrace TM changes Commit 8d460f6156cd ("powerpc/process: Add the function flush_tmregs_to_thread") added flush_tmregs_to_thread() and included the assumption that it would only be called for a task which is not current. Although this is correct for ptrace, when generating a core dump, some of the routines which call flush_tmregs_to_thread() are called. This leads to a WARNing such as: Not expecting ptrace on self: TM regs may be incorrect ------------[ cut here ]------------ WARNING: CPU: 123 PID: 7727 at arch/powerpc/kernel/process.c:1088 flush_tmregs_to_thread+0x78/0x80 CPU: 123 PID: 7727 Comm: libvirtd Not tainted 4.8.0-rc1-gcc6x-g61e8a0d #1 task: c000000fe631b600 task.stack: c000000fe63b0000 NIP: c00000000001a1a8 LR: c00000000001a1a4 CTR: c000000000717780 REGS: c000000fe63b3420 TRAP: 0700 Not tainted (4.8.0-rc1-gcc6x-g61e8a0d) MSR: 900000010282b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]> CR: 28004222 XER: 20000000 ... NIP [c00000000001a1a8] flush_tmregs_to_thread+0x78/0x80 LR [c00000000001a1a4] flush_tmregs_to_thread+0x74/0x80 Call Trace: flush_tmregs_to_thread+0x74/0x80 (unreliable) vsr_get+0x64/0x1a0 elf_core_dump+0x604/0x1430 do_coredump+0x5fc/0x1200 get_signal+0x398/0x740 do_signal+0x54/0x2b0 do_notify_resume+0x98/0xb0 ret_from_except_lite+0x70/0x74 So fix flush_tmregs_to_thread() to detect the case where it is called on current, and a transaction is active, and in that case flush the TM regs to the thread_struct. This patch also moves flush_tmregs_to_thread() into ptrace.c as it is only called from that file. Fixes: 8d460f6156cd ("powerpc/process: Add the function flush_tmregs_to_thread") Signed-off-by: Cyril Bur <cyrilbur@gmail.com> [mpe: Flesh out change log] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> cheers
On Wed, 2016-10-08 at 05:44:46 UTC, Cyril Bur wrote: > There was an assumption that flush_tmregs_to_thread() would only be > called for a task which is not current. And a warning could be shown > to indicate that current is being ptraced. > > In the event of a core dump the current threads state is needed. This > means that flush_tmregs_to_thread() must do its best to flush even for > current. > > This patch also moves flush_tmregs_to_thread() into ptrace.c as it is > only called from that file. > > Signed-off-by: Cyril Bur <cyrilbur@gmail.com> Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/c7a318ba868c61fc9be710a497 cheers
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h index 0a74ebe..17c8380 100644 --- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -75,14 +75,6 @@ static inline void disable_kernel_spe(void) static inline void __giveup_spe(struct task_struct *t) { } #endif -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM -extern void flush_tmregs_to_thread(struct task_struct *); -#else -static inline void flush_tmregs_to_thread(struct task_struct *t) -{ -} -#endif - static inline void clear_task_ebb(struct task_struct *t) { #ifdef CONFIG_PPC_BOOK3S_64 diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 58ccf86..9ee2623 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1074,26 +1074,6 @@ static inline void restore_sprs(struct thread_struct *old_thread, #endif } -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM -void flush_tmregs_to_thread(struct task_struct *tsk) -{ - /* - * Process self tracing is not yet supported through - * ptrace interface. Ptrace generic code should have - * prevented this from happening in the first place. - * Warn once here with the message, if some how it - * is attempted. - */ - WARN_ONCE(tsk == current, - "Not expecting ptrace on self: TM regs may be incorrect\n"); - - /* - * If task is not current, it should have been flushed - * already to it's thread_struct during __switch_to(). - */ -} -#endif - struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *new) { diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 4f3c575..bf91658 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -38,6 +38,7 @@ #include <asm/page.h> #include <asm/pgtable.h> #include <asm/switch_to.h> +#include <asm/tm.h> #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> @@ -118,6 +119,24 @@ static const struct pt_regs_offset regoffset_table[] = { REG_OFFSET_END, }; +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM +static void flush_tmregs_to_thread(struct task_struct *tsk) +{ + /* + * If task is not current, it will have been flushed already to + * it's thread_struct during __switch_to(). + * + * A reclaim flushes ALL the state. + */ + + if (tsk == current && MSR_TM_SUSPENDED(mfmsr())) + tm_reclaim_current(TM_CAUSE_SIGNAL); + +} +#else +static inline void flush_tmregs_to_thread(struct task_struct *tsk) { } +#endif + /** * regs_query_register_offset() - query register offset from its name * @name: the name of a register
There was an assumption that flush_tmregs_to_thread() would only be called for a task which is not current. And a warning could be shown to indicate that current is being ptraced. In the event of a core dump the current threads state is needed. This means that flush_tmregs_to_thread() must do its best to flush even for current. This patch also moves flush_tmregs_to_thread() into ptrace.c as it is only called from that file. Signed-off-by: Cyril Bur <cyrilbur@gmail.com> --- arch/powerpc/include/asm/switch_to.h | 8 -------- arch/powerpc/kernel/process.c | 20 -------------------- arch/powerpc/kernel/ptrace.c | 19 +++++++++++++++++++ 3 files changed, 19 insertions(+), 28 deletions(-)