powerpc/entry32: Blacklist exception exit points for kprobe.

kprobe does not handle events happening in real mode.

The very last part of exception exits cannot support a trap.
Blacklist them from kprobe.

While we are at it, remove exc_exit_start symbol which is not
used to avoid having to blacklist it.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/098b0fd3f6299aa1bd692bd576bd7012c84608de.1585670437.git.christophe.leroy@c-s.fr

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 5fa192b33509acaa67c9b7e5b8aed23644d4492d..217ebdf5b00b3da25fc9dea5c8c104e315d26d4c 100644 (file)
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -806,6 +806,7 @@ fast_exception_return:
        lwz     r11,GPR11(r11)
        SYNC
        RFI
+_ASM_NOKPROBE_SYMBOL(fast_exception_return)
 
 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
 /* check if the exception happened in a restartable section */
@@ -1041,6 +1042,8 @@ exc_exit_restart:
 exc_exit_restart_end:
        SYNC
        RFI
+_ASM_NOKPROBE_SYMBOL(exc_exit_restart)
+_ASM_NOKPROBE_SYMBOL(exc_exit_restart_end)
 
 #else /* !(CONFIG_4xx || CONFIG_BOOKE) */
        /*
@@ -1062,7 +1065,6 @@ exc_exit_restart_end:
 exc_exit_restart:
        lwz     r11,_NIP(r1)
        lwz     r12,_MSR(r1)
-exc_exit_start:
        mtspr   SPRN_SRR0,r11
        mtspr   SPRN_SRR1,r12
        REST_2GPRS(11, r1)
@@ -1071,6 +1073,7 @@ exc_exit_start:
 exc_exit_restart_end:
        rfi
        b       .                       /* prevent prefetch past rfi */
+_ASM_NOKPROBE_SYMBOL(exc_exit_restart)
 
 /*
  * Returning from a critical interrupt in user mode doesn't need
@@ -1182,6 +1185,7 @@ ret_from_crit_exc:
        mtspr   SPRN_SRR0,r9;
        mtspr   SPRN_SRR1,r10;
        RET_FROM_EXC_LEVEL(SPRN_CSRR0, SPRN_CSRR1, PPC_RFCI)
+_ASM_NOKPROBE_SYMBOL(ret_from_crit_exc)
 #endif /* CONFIG_40x */
 
 #ifdef CONFIG_BOOKE
@@ -1193,6 +1197,7 @@ ret_from_crit_exc:
        RESTORE_xSRR(SRR0,SRR1);
        RESTORE_MMU_REGS;
        RET_FROM_EXC_LEVEL(SPRN_CSRR0, SPRN_CSRR1, PPC_RFCI)
+_ASM_NOKPROBE_SYMBOL(ret_from_crit_exc)
 
        .globl  ret_from_debug_exc
 ret_from_debug_exc:
@@ -1203,6 +1208,7 @@ ret_from_debug_exc:
        RESTORE_xSRR(CSRR0,CSRR1);
        RESTORE_MMU_REGS;
        RET_FROM_EXC_LEVEL(SPRN_DSRR0, SPRN_DSRR1, PPC_RFDI)
+_ASM_NOKPROBE_SYMBOL(ret_from_debug_exc)
 
        .globl  ret_from_mcheck_exc
 ret_from_mcheck_exc:
@@ -1214,6 +1220,7 @@ ret_from_mcheck_exc:
        RESTORE_xSRR(DSRR0,DSRR1);
        RESTORE_MMU_REGS;
        RET_FROM_EXC_LEVEL(SPRN_MCSRR0, SPRN_MCSRR1, PPC_RFMCI)
+_ASM_NOKPROBE_SYMBOL(ret_from_mcheck_exc)
 #endif /* CONFIG_BOOKE */
 
 /*