Re: [PATCH v4 3/9] powerpc/kprobes/optprobes: Move over to patch_instruction

[Christophe LEROY]

Le 27/06/2017 à 09:48, Balbir Singh a écrit :

With text moving to read-only migrate optprobes to using
the patch_instruction infrastructure. Without this optprobes
will fail and complain.

Signed-off-by: Balbir Singh <bsinghar...@gmail.com>

Didn't Michael picked it up already ?

Christophe

---
  arch/powerpc/kernel/optprobes.c | 58 ++++++++++++++++++++++++++---------------
  1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index ec60ed0..1c7326c 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c
@@ -158,12 +158,13 @@ void arch_remove_optimized_kprobe(struct optimized_kprobe 
*op)
  void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)
  {
        /* addis r4,0,(insn)@h */
-       *addr++ = PPC_INST_ADDIS | ___PPC_RT(4) |
-                 ((val >> 16) & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ADDIS | ___PPC_RT(4) |
+                                       ((val >> 16) & 0xffff));
+       addr++;

/* ori r4,r4,(insn)@l */

-       *addr = PPC_INST_ORI | ___PPC_RA(4) | ___PPC_RS(4) |
-               (val & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(4) |
+                                       ___PPC_RS(4) | (val & 0xffff));
  }

/*

@@ -173,24 +174,28 @@ void patch_imm32_load_insns(unsigned int val, 
kprobe_opcode_t *addr)
  void patch_imm64_load_insns(unsigned long val, kprobe_opcode_t *addr)
  {
        /* lis r3,(op)@highest */
-       *addr++ = PPC_INST_ADDIS | ___PPC_RT(3) |
-                 ((val >> 48) & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ADDIS | ___PPC_RT(3) |
+                                       ((val >> 48) & 0xffff));
+       addr++;

/* ori r3,r3,(op)@higher */

-       *addr++ = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
-                 ((val >> 32) & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(3) |
+                               ___PPC_RS(3) | ((val >> 32) & 0xffff));
+       addr++;

/* rldicr r3,r3,32,31 */

-       *addr++ = PPC_INST_RLDICR | ___PPC_RA(3) | ___PPC_RS(3) |
-                 __PPC_SH64(32) | __PPC_ME64(31);
+       patch_instruction((unsigned int *)addr, PPC_INST_RLDICR | ___PPC_RA(3) |
+                               ___PPC_RS(3) | __PPC_SH64(32) | __PPC_ME64(31));
+       addr++;

/* oris r3,r3,(op)@h */

-       *addr++ = PPC_INST_ORIS | ___PPC_RA(3) | ___PPC_RS(3) |
-                 ((val >> 16) & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ORIS | ___PPC_RA(3) |
+                                       ___PPC_RS(3) | ((val >> 16) & 0xffff));
+       addr++;

/* ori r3,r3,(op)@l */

-       *addr = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
-               (val & 0xffff);
+       patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(3) |
+                               ___PPC_RS(3) | (val & 0xffff));
  }

int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)

@@ -198,7 +203,8 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe 
*op, struct kprobe *p)
        kprobe_opcode_t *buff, branch_op_callback, branch_emulate_step;
        kprobe_opcode_t *op_callback_addr, *emulate_step_addr;
        long b_offset;
-       unsigned long nip;
+       unsigned long nip, size;
+       int rc, i;

kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE; @@ -231,8 +237,15 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)

                goto error;

/* Setup template */

-       memcpy(buff, optprobe_template_entry,
-                       TMPL_END_IDX * sizeof(kprobe_opcode_t));
+       /* We can optimize this via patch_instruction_window later */
+       size = (TMPL_END_IDX * sizeof(kprobe_opcode_t)) / sizeof(int);
+       pr_devel("Copying template to %p, size %lu\n", buff, size);
+       for (i = 0; i < size; i++) {
+               rc = patch_instruction((unsigned int *)buff + i,
+                       *((unsigned int *)(optprobe_template_entry) + i));
+               if (rc < 0)
+                       goto error;
+       }

/*

         * Fixup the template with instructions to:
@@ -261,8 +274,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe 
*op, struct kprobe *p)
        if (!branch_op_callback || !branch_emulate_step)
                goto error;

- buff[TMPL_CALL_HDLR_IDX] = branch_op_callback;

-       buff[TMPL_EMULATE_IDX] = branch_emulate_step;
+       patch_instruction((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
+                               branch_op_callback);
+       patch_instruction((unsigned int *)buff + TMPL_EMULATE_IDX,
+                               branch_emulate_step);

/*

         * 3. load instruction to be emulated into relevant register, and
@@ -272,8 +287,9 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe 
*op, struct kprobe *p)
        /*
         * 4. branch back from trampoline
         */
-       buff[TMPL_RET_IDX] = create_branch((unsigned int *)buff + TMPL_RET_IDX,
-                               (unsigned long)nip, 0);
+       patch_instruction((unsigned int *)buff + TMPL_RET_IDX,
+                               create_branch((unsigned int *)buff +
+                               TMPL_RET_IDX, (unsigned long)nip, 0));

flush_icache_range((unsigned long)buff,

                           (unsigned long)(&buff[TMPL_END_IDX]));