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Subject[PATCH v2 10/12] powerpc/entry32: Blacklist exception entry points for kprobe.
Date
kprobe does not handle events happening in real mode.

As exception entry points are running with MMU disabled,
blacklist them.

The handling of TLF_NAPPING and TLF_SLEEPING is moved before the
CONFIG_TRACE_IRQFLAGS which contains 'reenable_mmu' because from there
kprobe will be possible as the kernel will run with MMU enabled.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
v2: Moved TLF_NAPPING and TLF_SLEEPING handling
---
arch/powerpc/kernel/entry_32.S | 37 ++++++++++++++++++++--------------
1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 94f78c03cb79..215aa3a6d4f7 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -51,6 +51,7 @@ mcheck_transfer_to_handler:
mfspr r0,SPRN_DSRR1
stw r0,_DSRR1(r11)
/* fall through */
+_ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler)

.globl debug_transfer_to_handler
debug_transfer_to_handler:
@@ -59,6 +60,7 @@ debug_transfer_to_handler:
mfspr r0,SPRN_CSRR1
stw r0,_CSRR1(r11)
/* fall through */
+_ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler)

.globl crit_transfer_to_handler
crit_transfer_to_handler:
@@ -94,6 +96,7 @@ crit_transfer_to_handler:
rlwinm r0,r1,0,0,(31 - THREAD_SHIFT)
stw r0,KSP_LIMIT(r8)
/* fall through */
+_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
#endif

#ifdef CONFIG_40x
@@ -115,6 +118,7 @@ crit_transfer_to_handler:
rlwinm r0,r1,0,0,(31 - THREAD_SHIFT)
stw r0,KSP_LIMIT(r8)
/* fall through */
+_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler)
#endif

/*
@@ -127,6 +131,7 @@ crit_transfer_to_handler:
.globl transfer_to_handler_full
transfer_to_handler_full:
SAVE_NVGPRS(r11)
+_ASM_NOKPROBE_SYMBOL(transfer_to_handler_full)
/* fall through */

.globl transfer_to_handler
@@ -227,6 +232,23 @@ transfer_to_handler_cont:
SYNC
RFI /* jump to handler, enable MMU */

+#if defined (CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
+4: rlwinm r12,r12,0,~_TLF_NAPPING
+ stw r12,TI_LOCAL_FLAGS(r2)
+ b power_save_ppc32_restore
+
+7: rlwinm r12,r12,0,~_TLF_SLEEPING
+ stw r12,TI_LOCAL_FLAGS(r2)
+ lwz r9,_MSR(r11) /* if sleeping, clear MSR.EE */
+ rlwinm r9,r9,0,~MSR_EE
+ lwz r12,_LINK(r11) /* and return to address in LR */
+ kuap_restore r11, r2, r3, r4, r5
+ lwz r2, GPR2(r11)
+ b fast_exception_return
+#endif
+_ASM_NOKPROBE_SYMBOL(transfer_to_handler)
+_ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont)
+
#ifdef CONFIG_TRACE_IRQFLAGS
1: /* MSR is changing, re-enable MMU so we can notify lockdep. We need to
* keep interrupts disabled at this point otherwise we might risk
@@ -272,21 +294,6 @@ reenable_mmu:
bctr /* jump to handler */
#endif /* CONFIG_TRACE_IRQFLAGS */

-#if defined (CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
-4: rlwinm r12,r12,0,~_TLF_NAPPING
- stw r12,TI_LOCAL_FLAGS(r2)
- b power_save_ppc32_restore
-
-7: rlwinm r12,r12,0,~_TLF_SLEEPING
- stw r12,TI_LOCAL_FLAGS(r2)
- lwz r9,_MSR(r11) /* if sleeping, clear MSR.EE */
- rlwinm r9,r9,0,~MSR_EE
- lwz r12,_LINK(r11) /* and return to address in LR */
- kuap_restore r11, r2, r3, r4, r5
- lwz r2, GPR2(r11)
- b fast_exception_return
-#endif
-
#ifndef CONFIG_VMAP_STACK
/*
* On kernel stack overflow, load up an initial stack pointer
--
2.25.0
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