On Tue, Apr 7, 2020 at 9:15 PM Balamuruhan S [off-list ref] wrote:

On Mon, 2020-04-06 at 18:09 +1000, Jordan Niethe wrote:

quoted

Currently all instructions have the same length, but in preparation for
prefixed instructions introduce a function for returning instruction
length.

Signed-off-by: Jordan Niethe <redacted>
---
 arch/powerpc/include/asm/inst.h | 5 +++++
 arch/powerpc/kernel/kprobes.c   | 6 ++++--
 arch/powerpc/kernel/uprobes.c   | 2 +-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/inst.h

b/arch/powerpc/include/asm/inst.h
index 369b35ce964c..70b37a35a91a 100644

--- a/arch/powerpc/include/asm/inst.h
+++ b/arch/powerpc/include/asm/inst.h

@@ -17,6 +17,11 @@ static inline u32 ppc_inst_val(struct ppc_inst x)
      return x.val;
 }

+static inline bool ppc_inst_len(struct ppc_inst x)

return type shouldn't be a bool, `size_t` instead.

Thank you.

-- Bala

quoted

+{
+     return sizeof(struct ppc_inst);
+}
+
 static inline int ppc_inst_opcode(struct ppc_inst x)
 {
      return x.val >> 26;

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index ff53e5ef7e40..8d17cfdcdc54 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c

@@ -474,14 +474,16 @@ NOKPROBE_SYMBOL(trampoline_probe_handler);
  */
 int kprobe_post_handler(struct pt_regs *regs)
 {
+     int len;
      struct kprobe *cur = kprobe_running();
      struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

      if (!cur || user_mode(regs))
              return 0;

+     len = ppc_inst_len(ppc_inst_read((struct ppc_inst *)cur->ainsn.insn));
      /* make sure we got here for instruction we have a kprobe on */
-     if (((unsigned long)cur->ainsn.insn + 4) != regs->nip)
+     if (((unsigned long)cur->ainsn.insn + len) != regs->nip)
              return 0;

      if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {

@@ -490,7 +492,7 @@ int kprobe_post_handler(struct pt_regs *regs)
      }

      /* Adjust nip to after the single-stepped instruction */
-     regs->nip = (unsigned long)cur->addr + 4;
+     regs->nip = (unsigned long)cur->addr + len;
      regs->msr |= kcb->kprobe_saved_msr;

      /*Restore back the original saved kprobes variables and continue. */

diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c
index 31c870287f2b..8e63afa012ba 100644
--- a/arch/powerpc/kernel/uprobes.c
+++ b/arch/powerpc/kernel/uprobes.c

@@ -112,7 +112,7 @@ int arch_uprobe_post_xol(struct arch_uprobe *auprobe,

struct pt_regs *regs)
       * support doesn't exist and have to fix-up the next instruction
       * to be executed.
       */
-     regs->nip = utask->vaddr + MAX_UINSN_BYTES;
+     regs->nip = utask->vaddr + ppc_inst_len(auprobe->insn);

      user_disable_single_step(current);
      return 0;