ARM: Add an emulate flag to the kprobes/uprobes instruction decode functions

Add an emulate flag into the instruction interpreter, primarily for uprobes
support.

Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Jon Medhurst <tixy@linaro.org>

diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 468d4a980c6c1bcab4fb6b0aa004b3b94ae249a5..8795f9f819d5820285bd5e737456ddb7a3f802bb 100644 (file)
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -89,7 +89,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
        p->opcode = insn;
        p->ainsn.insn = tmp_insn;
 
-       switch ((*decode_insn)(insn, &p->ainsn, actions)) {
+       switch ((*decode_insn)(insn, &p->ainsn, true, actions)) {
        case INSN_REJECTED:     /* not supported */
                return -EINVAL;
 

diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h
index eee8089b1b934521704359f2e4628c8bdc1fc581..d0a24b73bcfad919e874889046a520b3a71d1ec6 100644 (file)
--- a/arch/arm/kernel/kprobes.h
+++ b/arch/arm/kernel/kprobes.h
@@ -35,6 +35,7 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi,
 
 typedef enum probes_insn (kprobe_decode_insn_t)(probes_opcode_t,
                                                struct arch_specific_insn *,
+                                               bool,
                                                const union decode_action *);
 
 #ifdef CONFIG_THUMB2_KERNEL

diff --git a/arch/arm/kernel/probes-arm.c b/arch/arm/kernel/probes-arm.c
index 738e5fc589289a437e44cf20a0c503c6a0ee9c03..8e7fde8765215d6e253eff17be35e6147b3da20a 100644 (file)
--- a/arch/arm/kernel/probes-arm.c
+++ b/arch/arm/kernel/probes-arm.c
@@ -725,10 +725,10 @@ static void __kprobes arm_singlestep(probes_opcode_t insn,
  */
 enum probes_insn __kprobes
 arm_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-                      const union decode_action *actions)
+                      bool emulate, const union decode_action *actions)
 {
        asi->insn_singlestep = arm_singlestep;
        asi->insn_check_cc = probes_condition_checks[insn>>28];
        return probes_decode_insn(insn, asi, probes_decode_arm_table, false,
-                                 actions);
+                                 emulate, actions);
 }

diff --git a/arch/arm/kernel/probes-arm.h b/arch/arm/kernel/probes-arm.h
index 7a5cce497a9b022832be39076abaa44d74845ed0..ea614dc5aaa3b3833021ab7432676d5e699911de 100644 (file)
--- a/arch/arm/kernel/probes-arm.h
+++ b/arch/arm/kernel/probes-arm.h
@@ -67,7 +67,7 @@ void __kprobes simulate_mov_ipsp(probes_opcode_t opcode,
 extern const union decode_item probes_decode_arm_table[];
 
 enum probes_insn arm_probes_decode_insn(probes_opcode_t,
-               struct arch_specific_insn *,
+               struct arch_specific_insn *, bool emulate,
                const union decode_action *actions);
 
 #endif

diff --git a/arch/arm/kernel/probes-thumb.c b/arch/arm/kernel/probes-thumb.c
index eab440f6b2d439b1718983f38a9cb21342fd744b..23e2cbdb37cb86823140fa9d45635dc8e7e2786d 100644 (file)
--- a/arch/arm/kernel/probes-thumb.c
+++ b/arch/arm/kernel/probes-thumb.c
@@ -863,20 +863,20 @@ static void __kprobes thumb32_singlestep(probes_opcode_t opcode,
 
 enum probes_insn __kprobes
 thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-                          const union decode_action *actions)
+                          bool emulate, const union decode_action *actions)
 {
        asi->insn_singlestep = thumb16_singlestep;
        asi->insn_check_cc = thumb_check_cc;
        return probes_decode_insn(insn, asi, probes_decode_thumb16_table, true,
-                                 actions);
+                                 emulate, actions);
 }
 
 enum probes_insn __kprobes
 thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-                          const union decode_action *actions)
+                          bool emulate, const union decode_action *actions)
 {
        asi->insn_singlestep = thumb32_singlestep;
        asi->insn_check_cc = thumb_check_cc;
        return probes_decode_insn(insn, asi, probes_decode_thumb32_table, true,
-                                 actions);
+                                 emulate, actions);
 }

diff --git a/arch/arm/kernel/probes-thumb.h b/arch/arm/kernel/probes-thumb.h
index d6f67c1df7af63d3e8d0940deba7cdcf4c3b753d..65e4250e9b789952ee1ed8be6e95c016bfda736d 100644 (file)
--- a/arch/arm/kernel/probes-thumb.h
+++ b/arch/arm/kernel/probes-thumb.h
@@ -89,9 +89,9 @@ extern const union decode_item probes_decode_thumb16_table[];
 
 enum probes_insn __kprobes
 thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-               const union decode_action *actions);
+               bool emulate, const union decode_action *actions);
 enum probes_insn __kprobes
 thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-               const union decode_action *actions);
+               bool emulate, const union decode_action *actions);
 
 #endif

diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c
index b6d9b855273c864c0a6cbfdfd7d3517df6ecc308..f9dff12cf85c8a1de2bab043bb921b336eb37664 100644 (file)
--- a/arch/arm/kernel/probes.c
+++ b/arch/arm/kernel/probes.c
@@ -257,7 +257,7 @@ set_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
  * non-zero value, the corresponding nibble in pinsn is validated and modified
  * according to the type.
  */
-static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs)
+static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs, bool modify)
 {
        probes_opcode_t insn = *pinsn;
        probes_opcode_t mask = 0xf; /* Start at least significant nibble */
@@ -323,7 +323,9 @@ static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs)
                insn |= new_bits & mask;
        }
 
-       *pinsn = insn;
+       if (modify)
+               *pinsn = insn;
+
        return true;
 
 reject:
@@ -385,13 +387,14 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
 int __kprobes
 probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
                   const union decode_item *table, bool thumb,
-                  const union decode_action *actions)
+                  bool emulate, const union decode_action *actions)
 {
        const struct decode_header *h = (struct decode_header *)table;
        const struct decode_header *next;
        bool matched = false;
 
-       insn = prepare_emulated_insn(insn, asi, thumb);
+       if (emulate)
+               insn = prepare_emulated_insn(insn, asi, thumb);
 
        for (;; h = next) {
                enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
@@ -406,7 +409,7 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
                if (!matched && (insn & h->mask.bits) != h->value.bits)
                        continue;
 
-               if (!decode_regs(&insn, regs))
+               if (!decode_regs(&insn, regs, emulate))
                        return INSN_REJECTED;
 
                switch (type) {
@@ -430,6 +433,11 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
 
                case DECODE_TYPE_EMULATE: {
                        struct decode_emulate *d = (struct decode_emulate *)h;
+
+                       if (!emulate)
+                               return actions[d->handler.action].decoder(insn,
+                                       asi, h);
+
                        asi->insn_handler = actions[d->handler.action].handler;
                        set_emulated_insn(insn, asi, thumb);
                        return INSN_GOOD;

diff --git a/arch/arm/kernel/probes.h b/arch/arm/kernel/probes.h
index 0c72e544175d5f1609e155a7204d26fad4be2e48..33cc30c50cf574a15eb04d517af91a70d2f4b22c 100644 (file)
--- a/arch/arm/kernel/probes.h
+++ b/arch/arm/kernel/probes.h
@@ -401,7 +401,7 @@ probes_insn_handler_t probes_emulate_none;
 
 int __kprobes
 probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
-               const union decode_item *table, bool thumb,
+               const union decode_item *table, bool thumb, bool emulate,
                const union decode_action *actions);
 
 #endif