Christophe Leroy wrote:
kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.

As already done for PPC64, do it for PPC32.

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
v2:
- Don't rename nonrecoverable as local, mark it noprobe instead.
- Add missing linux/kprobes.h include in pq2.c
---
 arch/powerpc/include/asm/ppc_asm.h           | 10 +++
 arch/powerpc/kernel/cpu_setup_6xx.S          |  4 +-
 arch/powerpc/kernel/entry_32.S               | 65 ++++++++------------
 arch/powerpc/kernel/fpu.S                    |  1 +
 arch/powerpc/kernel/idle_6xx.S               |  2 +-
 arch/powerpc/kernel/idle_e500.S              |  2 +-
 arch/powerpc/kernel/l2cr_6xx.S               |  2 +-
 arch/powerpc/kernel/misc.S                   |  2 +
 arch/powerpc/kernel/misc_32.S                |  4 +-
 arch/powerpc/kernel/swsusp_32.S              |  6 +-
 arch/powerpc/kernel/vector.S                 |  1 +
 arch/powerpc/mm/book3s32/hash_low.S          | 38 ++++++------
 arch/powerpc/mm/mem.c                        |  2 +
 arch/powerpc/platforms/52xx/lite5200_sleep.S |  2 +
 arch/powerpc/platforms/82xx/pq2.c            |  3 +
 arch/powerpc/platforms/83xx/suspend-asm.S    |  1 +
 arch/powerpc/platforms/powermac/cache.S      |  2 +
 arch/powerpc/platforms/powermac/sleep.S      | 13 ++--
 18 files changed, 86 insertions(+), 74 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc_asm.h 
b/arch/powerpc/include/asm/ppc_asm.h
index 6b03dff61a05..e8f34ba89497 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -267,8 +267,18 @@ GLUE(.,name):
        .pushsection "_kprobe_blacklist","aw";              \
        PPC_LONG (entry) ;                              \
        .popsection
+#define _NOKPROBE_ENTRY(entry)                         \
+       _ASM_NOKPROBE_SYMBOL(entry)                             \
+       _ENTRY(entry)
+#define _NOKPROBE_GLOBAL(entry)                                \
+       _ASM_NOKPROBE_SYMBOL(entry)                             \
+       _GLOBAL(entry)
 #else
 #define _ASM_NOKPROBE_SYMBOL(entry)
+#define _NOKPROBE_ENTRY(entry)                         \
+       _ENTRY(entry)
+#define _NOKPROBE_GLOBAL(entry)                                \
+       _GLOBAL(entry)
 #endif

Michael hasn't preferred including NOKPROBE variants of those macros previously, since he would like to see some cleanups there:
https://patchwork.ozlabs.org/patch/696138/


 #define FUNC_START(name)       _GLOBAL(name)
diff --git a/arch/powerpc/kernel/cpu_setup_6xx.S 
b/arch/powerpc/kernel/cpu_setup_6xx.S
index f6517f67265a..1cb947268546 100644
--- a/arch/powerpc/kernel/cpu_setup_6xx.S
+++ b/arch/powerpc/kernel/cpu_setup_6xx.S
@@ -276,7 +276,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NO_DPM)
  * in some 750 cpus where using a not yet initialized FPU register after
  * power on reset may hang the CPU
  */
-_GLOBAL(__init_fpu_registers)
+_NOKPROBE_GLOBAL(__init_fpu_registers)
        mfmsr   r10
        ori     r11,r10,MSR_FP
        mtmsr   r11
@@ -381,7 +381,7 @@ _GLOBAL(__save_cpu_setup)
  * restore CPU state as backed up by the previous
  * function. This does not include cache setting
  */
-_GLOBAL(__restore_cpu_setup)
+_NOKPROBE_GLOBAL(__restore_cpu_setup)
        /* Some CR fields are volatile, we back it up all */
        mfcr    r7

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 16af0d8d90a8..f788d586254d 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -44,24 +44,21 @@
        .align  12

 #ifdef CONFIG_BOOKE
-       .globl  mcheck_transfer_to_handler
-mcheck_transfer_to_handler:
+_NOKPROBE_ENTRY(mcheck_transfer_to_handler)
        mfspr   r0,SPRN_DSRR0
        stw     r0,_DSRR0(r11)
        mfspr   r0,SPRN_DSRR1
        stw     r0,_DSRR1(r11)
        /* fall through */

-       .globl  debug_transfer_to_handler
-debug_transfer_to_handler:
+_NOKPROBE_ENTRY(debug_transfer_to_handler)
        mfspr   r0,SPRN_CSRR0
        stw     r0,_CSRR0(r11)
        mfspr   r0,SPRN_CSRR1
        stw     r0,_CSRR1(r11)
        /* fall through */

-       .globl  crit_transfer_to_handler
-crit_transfer_to_handler:
+_NOKPROBE_ENTRY(crit_transfer_to_handler)
 #ifdef CONFIG_PPC_BOOK3E_MMU
        mfspr   r0,SPRN_MAS0
        stw     r0,MAS0(r11)
@@ -97,8 +94,7 @@ crit_transfer_to_handler:
 #endif

 #ifdef CONFIG_40x
-       .globl  crit_transfer_to_handler
-crit_transfer_to_handler:
+_NOKPROBE_ENTRY(crit_transfer_to_handler)
        lwz     r0,crit_r10@l(0)
        stw     r0,GPR10(r11)
        lwz     r0,crit_r11@l(0)
@@ -124,13 +120,11 @@ crit_transfer_to_handler:
  * Note that we rely on the caller having set cr0.eq iff the exception
  * occurred in kernel mode (i.e. MSR:PR = 0).
  */
-       .globl  transfer_to_handler_full
-transfer_to_handler_full:
+_NOKPROBE_ENTRY(transfer_to_handler_full)
        SAVE_NVGPRS(r11)
        /* fall through */

-       .globl  transfer_to_handler
-transfer_to_handler:
+_NOKPROBE_ENTRY(transfer_to_handler)
        stw     r2,GPR2(r11)
        stw     r12,_NIP(r11)
        stw     r9,_MSR(r11)
@@ -194,8 +188,7 @@ transfer_to_handler:
        bt-     31-TLF_NAPPING,4f
        bt-     31-TLF_SLEEPING,7f
 #endif /* CONFIG_PPC_BOOK3S_32 || CONFIG_E500 */
-       .globl transfer_to_handler_cont
-transfer_to_handler_cont:
+_NOKPROBE_ENTRY(transfer_to_handler_cont)
 3:
        mflr    r9
        tovirt_novmstack r2, r2         /* set r2 to current */
@@ -297,6 +290,7 @@ reenable_mmu:
  * On kernel stack overflow, load up an initial stack pointer
  * and call StackOverflow(regs), which should not return.
  */
+_ASM_NOKPROBE_SYMBOL(stack_ovf)
 stack_ovf:

The current convention is to add the NOKPROBE annotation at the _end_ of the associated function/symbol...

        /* sometimes we use a statically-allocated stack, which is OK. */
        lis     r12,_end@h
@@ -460,6 +454,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
        lwz     r7,_NIP(r1)
        lwz     r2,GPR2(r1)
        lwz     r1,GPR1(r1)
+syscall_exit_finish:
 #if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)
        mtspr   SPRN_NRI, r0
 #endif
@@ -467,6 +462,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
        mtspr   SPRN_SRR1,r8
        SYNC
        RFI
+_ASM_NOKPROBE_SYMBOL(syscall_exit_finish)

... like so.

 #ifdef CONFIG_44x
 2:     li      r7,0
        iccci   r0,r0
@@ -750,8 +746,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_SPE)
        addi    r1,r1,INT_FRAME_SIZE
        blr

-       .globl  fast_exception_return
-fast_exception_return:
+_NOKPROBE_ENTRY(fast_exception_return)
 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
        andi.   r10,r9,MSR_RI           /* check for recoverable interrupt */
        beq     1f                      /* if not, we've got problems */
@@ -780,8 +775,8 @@ fast_exception_return:

 #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
 /* check if the exception happened in a restartable section */
-1:     lis     r3,exc_exit_restart_end@ha
-       addi    r3,r3,exc_exit_restart_end@l
+1:     lis     r3,.Lexc_exit_restart_end@ha
+       addi    r3,r3,.Lexc_exit_restart_end@l
        cmplw   r12,r3
 #ifdef CONFIG_PPC_BOOK3S_601
        bge     2b
@@ -1005,15 +1000,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
        LOAD_REG_IMMEDIATE(r10,MSR_KERNEL & ~MSR_RI)
        SYNC
        mtmsr   r10             /* clear the RI bit */
-       .globl exc_exit_restart
-exc_exit_restart:
+_NOKPROBE_ENTRY(exc_exit_restart)
        lwz     r12,_NIP(r1)
        mtspr   SPRN_SRR0,r12
        mtspr   SPRN_SRR1,r9
        REST_4GPRS(9, r1)
        lwz     r1,GPR1(r1)
-       .globl exc_exit_restart_end
-exc_exit_restart_end:
+.Lexc_exit_restart_end:
        SYNC
        RFI

@@ -1033,17 +1026,15 @@ exc_exit_restart_end:
        li      r10, 0
        stw     r10, 8(r1)
        REST_2GPRS(9, r1)
-       .globl exc_exit_restart
+_NOKPROBE_ENTRY(exc_exit_restart)
 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)
        lwz     r1,GPR1(r1)
-       .globl exc_exit_restart_end
-exc_exit_restart_end:
+.Lexc_exit_restart_end:

I think it would be good to break this into smaller patches to handle specific code paths, if possible. At the very least, it would be good to move changes to symbol visibility to a separate patch since this also changes the names printed in a backtrace.

- Naveen

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