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powerpc/ptrace: Fix coredump since ptrace TM changes

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Commit 8d460f6156 ("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: 8d460f6156 ("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>
This commit is contained in:
Cyril Bur 2016-08-10 15:44:46 +10:00 committed by Michael Ellerman
parent 1bc8b816cb
commit c7a318ba86
3 changed files with 19 additions and 28 deletions
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8
arch/powerpc/include/asm/switch_to.h
View File

@ -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

20
arch/powerpc/kernel/process.c
View File

@ -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)
{

19
arch/powerpc/kernel/ptrace.c
View File

@ -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