powerpc: Don't use CURRENT_THREAD_INFO to find the stack

[sfrench/cifs-2.6.git] / arch / powerpc / kernel / entry_64.S

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 435927f549c438614ae680d31775911b3600b417..21f1cb4d464e99f19eb82067783a4e373b1fa7d3 100644 (file)
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -236,18 +236,14 @@ system_call_exit:
        /*
         * Disable interrupts so current_thread_info()->flags can't change,
         * and so that we don't get interrupted after loading SRR0/1.
+        *
+        * Leave MSR_RI enabled for now, because with THREAD_INFO_IN_TASK we
+        * could fault on the load of the TI_FLAGS below.
         */
 #ifdef CONFIG_PPC_BOOK3E
        wrteei  0
 #else
-       /*
-        * For performance reasons we clear RI the same time that we
-        * clear EE. We only need to clear RI just before we restore r13
-        * below, but batching it with EE saves us one expensive mtmsrd call.
-        * We have to be careful to restore RI if we branch anywhere from
-        * here (eg syscall_exit_work).
-        */
-       li      r11,0
+       li      r11,MSR_RI
        mtmsrd  r11,1
 #endif /* CONFIG_PPC_BOOK3E */
 
@@ -263,15 +259,7 @@ system_call_exit:
        bne     3f
 #endif
 2:     addi    r3,r1,STACK_FRAME_OVERHEAD
-#ifdef CONFIG_PPC_BOOK3S
-       li      r10,MSR_RI
-       mtmsrd  r10,1           /* Restore RI */
-#endif
        bl      restore_math
-#ifdef CONFIG_PPC_BOOK3S
-       li      r11,0
-       mtmsrd  r11,1
-#endif
        ld      r8,_MSR(r1)
        ld      r3,RESULT(r1)
        li      r11,-MAX_ERRNO
@@ -287,6 +275,16 @@ END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
        andi.   r6,r8,MSR_PR
        ld      r4,_LINK(r1)
 
+#ifdef CONFIG_PPC_BOOK3S
+       /*
+        * Clear MSR_RI, MSR_EE is already and remains disabled. We could do
+        * this later, but testing shows that doing it here causes less slow
+        * down than doing it closer to the rfid.
+        */
+       li      r11,0
+       mtmsrd  r11,1
+#endif
+
        beq-    1f
        ACCOUNT_CPU_USER_EXIT(r13, r11, r12)
 
@@ -363,10 +361,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
        b       .Lsyscall_exit
        
 .Lsyscall_exit_work:
-#ifdef CONFIG_PPC_BOOK3S
-       li      r10,MSR_RI
-       mtmsrd  r10,1           /* Restore RI */
-#endif
        /* If TIF_RESTOREALL is set, don't scribble on either r3 or ccr.
         If TIF_NOERROR is set, just save r3 as it is. */
 
@@ -695,7 +689,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S)
 2:
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
-       CURRENT_THREAD_INFO(r7, r8)  /* base of new stack */
+       clrrdi  r7, r8, THREAD_SHIFT    /* base of new stack */
        /* Note: this uses SWITCH_FRAME_SIZE rather than INT_FRAME_SIZE
           because we don't need to leave the 288-byte ABI gap at the
           top of the kernel stack. */
@@ -1002,6 +996,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
        ld      r2,_NIP(r1)
        mtspr   SPRN_SRR0,r2
 
+       /*
+        * Leaving a stale exception_marker on the stack can confuse
+        * the reliable stack unwinder later on. Clear it.
+        */
+       li      r2,0
+       std     r2,STACK_FRAME_OVERHEAD-16(r1)
+
        ld      r0,GPR0(r1)
        ld      r2,GPR2(r1)
        ld      r3,GPR3(r1)