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authorJon Medhurst <tixy@yxit.co.uk>2011-07-02 15:36:32 +0100
committerTixy <tixy@medhuaa1.miniserver.com>2011-07-13 17:32:43 +0000
commit3f92dfed6a9a5f490128c8e7cc6a64dfe412994f (patch)
tree1d503b19d01075dfd1db1023b8d0e787f9d58bb6 /arch/arm/kernel
parent0d1a095aa1e6e2a233bfb1729e15233e77f69d54 (diff)
ARM: kprobes: Decode 16-bit Thumb hint instructions
For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Diffstat (limited to 'arch/arm/kernel')
-rw-r--r--arch/arm/kernel/kprobes-common.c9
-rw-r--r--arch/arm/kernel/kprobes-thumb.c35
-rw-r--r--arch/arm/kernel/kprobes.h3
3 files changed, 46 insertions, 1 deletions
diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c
index 1cb6a82a5e24..3a3e765d2090 100644
--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -142,6 +142,15 @@ kprobe_check_cc * const kprobe_condition_checks[16] = {
};
+void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs)
+{
+}
+
+void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs)
+{
+ p->ainsn.insn_fn();
+}
+
/*
* Prepare an instruction slot to receive an instruction for emulating.
* This is done by placing a subroutine return after the location where the
diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index 973c3eb1243a..7dcf6df4a85c 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -26,6 +26,39 @@
*/
#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
+static const union decode_item t16_table_1011[] = {
+ /* Miscellaneous 16-bit instructions */
+
+ /*
+ * If-Then, and hints
+ * 1011 1111 xxxx xxxx
+ */
+
+ /* YIELD 1011 1111 0001 0000 */
+ DECODE_OR (0xffff, 0xbf10),
+ /* SEV 1011 1111 0100 0000 */
+ DECODE_EMULATE (0xffff, 0xbf40, kprobe_emulate_none),
+ /* NOP 1011 1111 0000 0000 */
+ /* WFE 1011 1111 0010 0000 */
+ /* WFI 1011 1111 0011 0000 */
+ DECODE_SIMULATE (0xffcf, 0xbf00, kprobe_simulate_nop),
+ /* Unassigned hints 1011 1111 xxxx 0000 */
+ DECODE_REJECT (0xff0f, 0xbf00),
+
+ DECODE_END
+};
+
+const union decode_item kprobe_decode_thumb16_table[] = {
+
+ /*
+ * Miscellaneous 16-bit instructions
+ * 1011 xxxx xxxx xxxx
+ */
+ DECODE_TABLE (0xf000, 0xb000, t16_table_1011),
+
+ DECODE_END
+};
+
static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
{
if (unlikely(in_it_block(cpsr)))
@@ -52,7 +85,7 @@ thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
{
asi->insn_singlestep = thumb16_singlestep;
asi->insn_check_cc = thumb_check_cc;
- return INSN_REJECTED;
+ return kprobe_decode_insn(insn, asi, kprobe_decode_thumb16_table, true);
}
enum kprobe_insn __kprobes
diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h
index c00681ce5cce..36e07684fe08 100644
--- a/arch/arm/kernel/kprobes.h
+++ b/arch/arm/kernel/kprobes.h
@@ -95,6 +95,9 @@ static inline unsigned long it_advance(unsigned long cpsr)
return cpsr;
}
+void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs);
+void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs);
+
/*
* Test if load/store instructions writeback the address register.
* if P (bit 24) == 0 or W (bit 21) == 1