[PATCH v3 5/6] powerpc/64s: Blacklist functions invoked on a trap

["Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>]

Blacklist all functions involved while handling a trap. We:
- convert some of the symbols into private symbols,
- remove the duplicate 'restore' symbol, and
- blacklist most functions involved while handling a trap.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/entry_64.S       | 47 +++++++++++++++++++++---------------
 arch/powerpc/kernel/exceptions-64s.S |  2 ++
 arch/powerpc/kernel/traps.c          |  3 +++
 3 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index feeeadc9aa71..d376f07153d7 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -184,7 +184,7 @@ system_call:			/* label this so stack traces look sane */
 #ifdef CONFIG_PPC_BOOK3S
 	/* No MSR:RI on BookE */
 	andi.	r10,r8,MSR_RI
-	beq-	unrecov_restore
+	beq-	.Lunrecov_restore
 #endif
 	/*
 	 * Disable interrupts so current_thread_info()->flags can't change,
@@ -424,6 +424,7 @@ _GLOBAL(save_nvgprs)
 	clrrdi	r0,r11,1
 	std	r0,_TRAP(r1)
 	blr
+_ASM_NOKPROBE_SYMBOL(save_nvgprs);
 
 	
 /*
@@ -672,18 +673,18 @@ _GLOBAL(ret_from_except_lite)
 	 * Use the internal debug mode bit to do this.
 	 */
 	andis.	r0,r3,DBCR0_IDM@h
-	beq	restore
+	beq	fast_exc_return_irq
 	mfmsr	r0
 	rlwinm	r0,r0,0,~MSR_DE	/* Clear MSR.DE */
 	mtmsr	r0
 	mtspr	SPRN_DBCR0,r3
 	li	r10, -1
 	mtspr	SPRN_DBSR,r10
-	b	restore
+	b	fast_exc_return_irq
 #else
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	restore_math
-	b	restore
+	b	fast_exc_return_irq
 #endif
 1:	andi.	r0,r4,_TIF_NEED_RESCHED
 	beq	2f
@@ -696,7 +697,7 @@ _GLOBAL(ret_from_except_lite)
 	bne	3f		/* only restore TM if nothing else to do */
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	restore_tm_state
-	b	restore
+	b	fast_exc_return_irq
 3:
 #endif
 	bl	save_nvgprs
@@ -748,14 +749,14 @@ resume_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Check if we need to preempt */
 	andi.	r0,r4,_TIF_NEED_RESCHED
-	beq+	restore
+	beq+	fast_exc_return_irq
 	/* Check that preempt_count() == 0 and interrupts are enabled */
 	lwz	r8,TI_PREEMPT(r9)
 	cmpwi	cr1,r8,0
 	ld	r0,SOFTE(r1)
 	cmpdi	r0,0
 	crandc	eq,cr1*4+eq,eq
-	bne	restore
+	bne	fast_exc_return_irq
 
 	/*
 	 * Here we are preempting the current task. We want to make
@@ -786,7 +787,6 @@ resume_kernel:
 
 	.globl	fast_exc_return_irq
 fast_exc_return_irq:
-restore:
 	/*
 	 * This is the main kernel exit path. First we check if we
 	 * are about to re-enable interrupts
@@ -794,11 +794,11 @@ restore:
 	ld	r5,SOFTE(r1)
 	lbz	r6,PACASOFTIRQEN(r13)
 	cmpwi	cr0,r5,0
-	beq	restore_irq_off
+	beq	.Lrestore_irq_off
 
 	/* We are enabling, were we already enabled ? Yes, just return */
 	cmpwi	cr0,r6,1
-	beq	cr0,do_restore
+	beq	cr0,.Ldo_restore
 
 	/*
 	 * We are about to soft-enable interrupts (we are hard disabled
@@ -807,14 +807,14 @@ restore:
 	 */
 	lbz	r0,PACAIRQHAPPENED(r13)
 	cmpwi	cr0,r0,0
-	bne-	restore_check_irq_replay
+	bne-	.Lrestore_check_irq_replay
 
 	/*
 	 * Get here when nothing happened while soft-disabled, just
 	 * soft-enable and move-on. We will hard-enable as a side
 	 * effect of rfi
 	 */
-restore_no_replay:
+.Lrestore_no_replay:
 	TRACE_ENABLE_INTS
 	li	r0,1
 	stb	r0,PACASOFTIRQEN(r13);
@@ -822,7 +822,7 @@ restore_no_replay:
 	/*
 	 * Final return path. BookE is handled in a different file
 	 */
-do_restore:
+.Ldo_restore:
 #ifdef CONFIG_PPC_BOOK3E
 	b	exception_return_book3e
 #else
@@ -856,7 +856,7 @@ fast_exception_return:
 	REST_8GPRS(5, r1)
 
 	andi.	r0,r3,MSR_RI
-	beq-	unrecov_restore
+	beq-	.Lunrecov_restore
 
 	/* Load PPR from thread struct before we clear MSR:RI */
 BEGIN_FTR_SECTION
@@ -914,7 +914,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	 * make sure that in this case, we also clear PACA_IRQ_HARD_DIS
 	 * or that bit can get out of sync and bad things will happen
 	 */
-restore_irq_off:
+.Lrestore_irq_off:
 	ld	r3,_MSR(r1)
 	lbz	r7,PACAIRQHAPPENED(r13)
 	andi.	r0,r3,MSR_EE
@@ -924,13 +924,13 @@ restore_irq_off:
 1:	li	r0,0
 	stb	r0,PACASOFTIRQEN(r13);
 	TRACE_DISABLE_INTS
-	b	do_restore
+	b	.Ldo_restore
 
 	/*
 	 * Something did happen, check if a re-emit is needed
 	 * (this also clears paca->irq_happened)
 	 */
-restore_check_irq_replay:
+.Lrestore_check_irq_replay:
 	/* XXX: We could implement a fast path here where we check
 	 * for irq_happened being just 0x01, in which case we can
 	 * clear it and return. That means that we would potentially
@@ -940,7 +940,7 @@ restore_check_irq_replay:
 	 */
 	bl	__check_irq_replay
 	cmpwi	cr0,r3,0
- 	beq	restore_no_replay
+	beq	.Lrestore_no_replay
  
 	/*
 	 * We need to re-emit an interrupt. We do so by re-using our
@@ -989,10 +989,17 @@ restore_check_irq_replay:
 #endif /* CONFIG_PPC_DOORBELL */
 1:	b	ret_from_except /* What else to do here ? */
  
-unrecov_restore:
+.Lunrecov_restore:
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	unrecoverable_exception
-	b	unrecov_restore
+	b	.Lunrecov_restore
+
+_ASM_NOKPROBE_SYMBOL(ret_from_except);
+_ASM_NOKPROBE_SYMBOL(ret_from_except_lite);
+_ASM_NOKPROBE_SYMBOL(resume_kernel);
+_ASM_NOKPROBE_SYMBOL(fast_exc_return_irq);
+_ASM_NOKPROBE_SYMBOL(fast_exception_return);
+
 
 #ifdef CONFIG_PPC_RTAS
 /*
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 2df6d7b3070f..0d025dfb52d8 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1589,6 +1589,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
 1:	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	kernel_bad_stack
 	b	1b
+_ASM_NOKPROBE_SYMBOL(bad_stack);
 
 /*
  * When doorbell is triggered from system reset wakeup, the message is
@@ -1650,3 +1651,4 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
 1:
 	blr
 
+_ASM_NOKPROBE_SYMBOL(__replay_interrupt)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index d4e545d27ef9..bfcfd9ef09f2 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -237,6 +237,7 @@ void die(const char *str, struct pt_regs *regs, long err)
 		err = 0;
 	oops_end(flags, regs, err);
 }
+NOKPROBE_SYMBOL(die);
 
 void user_single_step_siginfo(struct task_struct *tsk,
 				struct pt_regs *regs, siginfo_t *info)
@@ -1968,6 +1969,7 @@ void unrecoverable_exception(struct pt_regs *regs)
 	       regs->trap, regs->nip);
 	die("Unrecoverable exception", regs, SIGABRT);
 }
+NOKPROBE_SYMBOL(unrecoverable_exception);
 
 #if defined(CONFIG_BOOKE_WDT) || defined(CONFIG_40x)
 /*
@@ -1998,6 +2000,7 @@ void kernel_bad_stack(struct pt_regs *regs)
 	       regs->gpr[1], regs->nip);
 	die("Bad kernel stack pointer", regs, SIGABRT);
 }
+NOKPROBE_SYMBOL(kernel_bad_stack);
 
 void __init trap_init(void)
 {
-- 
2.13.1