1 files changed, 38 insertions, 12 deletions

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index e6474a45cef5..2d47cc79e5b3 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -470,9 +470,9 @@ static int save_user_regs(struct pt_regs *regs, struct mcontext __user *frame,
                 return 1;
 
         if (sigret) {
-                /* Set up the sigreturn trampoline: li r0,sigret; sc */
-                if (__put_user(0x38000000UL + sigret, &frame->tramp[0])
-                    || __put_user(0x44000002UL, &frame->tramp[1]))
+                /* Set up the sigreturn trampoline: li 0,sigret; sc */
+                if (__put_user(PPC_INST_ADDI + sigret, &frame->tramp[0])
+                    || __put_user(PPC_INST_SC, &frame->tramp[1]))
                         return 1;
                 flush_icache_range((unsigned long) &frame->tramp[0],
                                    (unsigned long) &frame->tramp[2]);
@@ -619,9 +619,9 @@ static int save_tm_user_regs(struct pt_regs *regs,
         if (__put_user(msr, &frame->mc_gregs[PT_MSR]))
                 return 1;
         if (sigret) {
-                /* Set up the sigreturn trampoline: li r0,sigret; sc */
-                if (__put_user(0x38000000UL + sigret, &frame->tramp[0])
-                    || __put_user(0x44000002UL, &frame->tramp[1]))
+                /* Set up the sigreturn trampoline: li 0,sigret; sc */
+                if (__put_user(PPC_INST_ADDI + sigret, &frame->tramp[0])
+                    || __put_user(PPC_INST_SC, &frame->tramp[1]))
                         return 1;
                 flush_icache_range((unsigned long) &frame->tramp[0],
                                    (unsigned long) &frame->tramp[2]);
@@ -848,7 +848,23 @@ static long restore_tm_user_regs(struct pt_regs *regs,
         /* If TM bits are set to the reserved value, it's an invalid context */
         if (MSR_TM_RESV(msr_hi))
                 return 1;
-        /* Pull in the MSR TM bits from the user context */
+
+        /*
+         * Disabling preemption, since it is unsafe to be preempted
+         * with MSR[TS] set without recheckpointing.
+         */
+        preempt_disable();
+
+        /*
+         * CAUTION:
+         * After regs->MSR[TS] being updated, make sure that get_user(),
+         * put_user() or similar functions are *not* called. These
+         * functions can generate page faults which will cause the process
+         * to be de-scheduled with MSR[TS] set but without calling
+         * tm_recheckpoint(). This can cause a bug.
+         *
+         * Pull in the MSR TM bits from the user context
+         */
         regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr_hi & MSR_TS_MASK);
         /* Now, recheckpoint.  This loads up all of the checkpointed (older)
          * registers, including FP and V[S]Rs.  After recheckpointing, the
@@ -873,6 +889,8 @@ static long restore_tm_user_regs(struct pt_regs *regs,
         }
 #endif
 
+        preempt_enable();
+
         return 0;
 }
 #endif
@@ -1140,11 +1158,11 @@ SYSCALL_DEFINE0(rt_sigreturn)
 {
         struct rt_sigframe __user *rt_sf;
         struct pt_regs *regs = current_pt_regs();
+        int tm_restore = 0;
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
         struct ucontext __user *uc_transact;
         unsigned long msr_hi;
         unsigned long tmp;
-        int tm_restore = 0;
 #endif
         /* Always make any pending restarted system calls return -EINTR */
         current->restart_block.fn = do_no_restart_syscall;
@@ -1192,11 +1210,19 @@ SYSCALL_DEFINE0(rt_sigreturn)
                                 goto bad;
                 }
         }
-        if (!tm_restore)
-                /* Fall through, for non-TM restore */
+        if (!tm_restore) {
+                /*
+                 * Unset regs->msr because ucontext MSR TS is not
+                 * set, and recheckpoint was not called. This avoid
+                 * hitting a TM Bad thing at RFID
+                 */
+                regs->msr &= ~MSR_TS_MASK;
+        }
+        /* Fall through, for non-TM restore */
 #endif
-        if (do_setcontext(&rt_sf->uc, regs, 1))
-                goto bad;
+        if (!tm_restore)
+                if (do_setcontext(&rt_sf->uc, regs, 1))
+                        goto bad;
 
         /*
          * It's not clear whether or why it is desirable to save the