[PATCH V3 1/6] arm64: kprobe: protect/rename few definitions to be reused by uprobe

Pratyush Anand
2016-11-02T09:11:08Z

decode-insn code has to be reused by arm64 uprobe implementation as well.
Therefore, this patch protects some portion of kprobe code and renames few
other, so that decode-insn functionality can be reused by uprobe even when
CONFIG_KPROBES is not defined.

kprobe_opcode_t and struct arch_specific_insn are also defined by
linux/kprobes.h, when CONFIG_KPROBES is not defined. So, protect these
definitions in asm/probes.h.

linux/kprobes.h already includes asm/kprobes.h. Therefore, remove inclusion
of asm/kprobes.h from decode-insn.c.

There are some definitions like kprobe_insn and kprobes_handler_t etc can
be re-used by uprobe. So, it would be better to remove 'k' from their
names.

struct arch_specific_insn is specific to kprobe. Therefore, introduce a new
struct arch_probe_insn which will be common for both kprobe and uprobe, so
that decode-insn code can be shared. Modify kprobe code accordingly.

Function arm_probe_decode_insn() will be needed by uprobe as well. So make
it global.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/arm64/include/asm/probes.h | 19 ++++++++++--------
arch/arm64/kernel/probes/decode-insn.c | 32 ++++++++++++++++--------------
arch/arm64/kernel/probes/decode-insn.h | 8 ++++++--
arch/arm64/kernel/probes/kprobes.c | 36 +++++++++++++++++-----------------
4 files changed, 52 insertions(+), 43 deletions(-)

diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h
index 5af574d632fa..e175a825b187 100644
--- a/arch/arm64/include/asm/probes.h
+++ b/arch/arm64/include/asm/probes.h
@@ -17,19 +17,22 @@

#include <asm/opcodes.h>

-struct kprobe;
-struct arch_specific_insn;
-
-typedef u32 kprobe_opcode_t;
-typedef void (kprobes_handler_t) (u32 opcode, long addr, struct pt_regs *);
+typedef u32 probe_opcode_t;
+typedef void (probes_handler_t) (u32 opcode, long addr, struct pt_regs *);

/* architecture specific copy of original instruction */
-struct arch_specific_insn {
- kprobe_opcode_t *insn;
+struct arch_probe_insn {
+ probe_opcode_t *insn;
pstate_check_t *pstate_cc;
- kprobes_handler_t *handler;
+ probes_handler_t *handler;
/* restore address after step xol */
unsigned long restore;
};
+#ifdef CONFIG_KPROBES
+typedef u32 kprobe_opcode_t;
+struct arch_specific_insn {
+ struct arch_probe_insn api;
+};
+#endif

#endif
diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
index d1731bf977ef..8a29d2982eec 100644
--- a/arch/arm64/kernel/probes/decode-insn.c
+++ b/arch/arm64/kernel/probes/decode-insn.c
@@ -78,8 +78,8 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn)
* INSN_GOOD If instruction is supported and uses instruction slot,
* INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot.
*/
-static enum kprobe_insn __kprobes
-arm_probe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
+enum probe_insn __kprobes
+arm_probe_decode_insn(probe_opcode_t insn, struct arch_probe_insn *api)
{
/*
* Instructions reading or modifying the PC won't work from the XOL
@@ -89,26 +89,26 @@ arm_probe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
return INSN_GOOD;

if (aarch64_insn_is_bcond(insn)) {
- asi->handler = simulate_b_cond;
+ api->handler = simulate_b_cond;
} else if (aarch64_insn_is_cbz(insn) ||
aarch64_insn_is_cbnz(insn)) {
- asi->handler = simulate_cbz_cbnz;
+ api->handler = simulate_cbz_cbnz;
} else if (aarch64_insn_is_tbz(insn) ||
aarch64_insn_is_tbnz(insn)) {
- asi->handler = simulate_tbz_tbnz;
+ api->handler = simulate_tbz_tbnz;
} else if (aarch64_insn_is_adr_adrp(insn)) {
- asi->handler = simulate_adr_adrp;
+ api->handler = simulate_adr_adrp;
} else if (aarch64_insn_is_b(insn) ||
aarch64_insn_is_bl(insn)) {
- asi->handler = simulate_b_bl;
+ api->handler = simulate_b_bl;
} else if (aarch64_insn_is_br(insn) ||
aarch64_insn_is_blr(insn) ||
aarch64_insn_is_ret(insn)) {
- asi->handler = simulate_br_blr_ret;
+ api->handler = simulate_br_blr_ret;
} else if (aarch64_insn_is_ldr_lit(insn)) {
- asi->handler = simulate_ldr_literal;
+ api->handler = simulate_ldr_literal;
} else if (aarch64_insn_is_ldrsw_lit(insn)) {
- asi->handler = simulate_ldrsw_literal;
+ api->handler = simulate_ldrsw_literal;
} else {
/*
* Instruction cannot be stepped out-of-line and we don't
@@ -120,6 +120,7 @@ arm_probe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
return INSN_GOOD_NO_SLOT;
}

+#ifdef CONFIG_KPROBES
static bool __kprobes
is_probed_address_atomic(kprobe_opcode_t *scan_start, kprobe_opcode_t *scan_end)
{
@@ -138,12 +139,12 @@ is_probed_address_atomic(kprobe_opcode_t *scan_start, kprobe_opcode_t *scan_end)
return false;
}

-enum kprobe_insn __kprobes
+enum probe_insn __kprobes
arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi)
{
- enum kprobe_insn decoded;
- kprobe_opcode_t insn = le32_to_cpu(*addr);
- kprobe_opcode_t *scan_end = NULL;
+ enum probe_insn decoded;
+ probe_opcode_t insn = le32_to_cpu(*addr);
+ probe_opcode_t *scan_end = NULL;
unsigned long size = 0, offset = 0;

/*
@@ -162,7 +163,7 @@ arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi)
else
scan_end = addr - MAX_ATOMIC_CONTEXT_SIZE;
}
- decoded = arm_probe_decode_insn(insn, asi);
+ decoded = arm_probe_decode_insn(insn, &asi->api);

if (decoded != INSN_REJECTED && scan_end)
if (is_probed_address_atomic(addr - 1, scan_end))
@@ -170,3 +171,4 @@ arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi)

return decoded;
}
+#endif
diff --git a/arch/arm64/kernel/probes/decode-insn.h b/arch/arm64/kernel/probes/decode-insn.h
index d438289646a6..76d3f315407f 100644
--- a/arch/arm64/kernel/probes/decode-insn.h
+++ b/arch/arm64/kernel/probes/decode-insn.h
@@ -23,13 +23,17 @@
*/
#define MAX_ATOMIC_CONTEXT_SIZE (128 / sizeof(kprobe_opcode_t))

-enum kprobe_insn {
+enum probe_insn {
INSN_REJECTED,
INSN_GOOD_NO_SLOT,
INSN_GOOD,
};

-enum kprobe_insn __kprobes
+#ifdef CONFIG_KPROBES
+enum probe_insn __kprobes
arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi);
+#endif
+enum probe_insn __kprobes
+arm_probe_decode_insn(probe_opcode_t insn, struct arch_probe_insn *asi);

#endif /* _ARM_KERNEL_KPROBES_ARM64_H */
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index f5077ea7af6d..1decd2b2c730 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -44,31 +44,31 @@ post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
{
/* prepare insn slot */
- p->ainsn.insn[0] = cpu_to_le32(p->opcode);
+ p->ainsn.api.insn[0] = cpu_to_le32(p->opcode);

- flush_icache_range((uintptr_t) (p->ainsn.insn),
- (uintptr_t) (p->ainsn.insn) +
+ flush_icache_range((uintptr_t) (p->ainsn.api.insn),
+ (uintptr_t) (p->ainsn.api.insn) +
MAX_INSN_SIZE * sizeof(kprobe_opcode_t));

/*
* Needs restoring of return address after stepping xol.
*/
- p->ainsn.restore = (unsigned long) p->addr +
+ p->ainsn.api.restore = (unsigned long) p->addr +
sizeof(kprobe_opcode_t);
}

static void __kprobes arch_prepare_simulate(struct kprobe *p)
{
/* This instructions is not executed xol. No need to adjust the PC */
- p->ainsn.restore = 0;
+ p->ainsn.api.restore = 0;
}

static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();

- if (p->ainsn.handler)
- p->ainsn.handler((u32)p->opcode, (long)p->addr, regs);
+ if (p->ainsn.api.handler)
+ p->ainsn.api.handler((u32)p->opcode, (long)p->addr, regs);

/* single step simulated, now go for post processing */
post_kprobe_handler(kcb, regs);
@@ -98,18 +98,18 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
return -EINVAL;

case INSN_GOOD_NO_SLOT: /* insn need simulation */
- p->ainsn.insn = NULL;
+ p->ainsn.api.insn = NULL;
break;

case INSN_GOOD: /* instruction uses slot */
- p->ainsn.insn = get_insn_slot();
- if (!p->ainsn.insn)
+ p->ainsn.api.insn = get_insn_slot();
+ if (!p->ainsn.api.insn)
return -ENOMEM;
break;
};

/* prepare the instruction */
- if (p->ainsn.insn)
+ if (p->ainsn.api.insn)
arch_prepare_ss_slot(p);
else
arch_prepare_simulate(p);
@@ -142,9 +142,9 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)

void __kprobes arch_remove_kprobe(struct kprobe *p)
{
- if (p->ainsn.insn) {
- free_insn_slot(p->ainsn.insn, 0);
- p->ainsn.insn = NULL;
+ if (p->ainsn.api.insn) {
+ free_insn_slot(p->ainsn.api.insn, 0);
+ p->ainsn.api.insn = NULL;
}
}

@@ -244,9 +244,9 @@ static void __kprobes setup_singlestep(struct kprobe *p,
}

- if (p->ainsn.insn) {
+ if (p->ainsn.api.insn) {
/* prepare for single stepping */
- slot = (unsigned long)p->ainsn.insn;
+ slot = (unsigned long)p->ainsn.api.insn;

set_ss_context(kcb, slot); /* mark pending ss */

@@ -295,8 +295,8 @@ post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs)
return;

/* return addr restore if non-branching insn */
- if (cur->ainsn.restore != 0)
- instruction_pointer_set(regs, cur->ainsn.restore);
+ if (cur->ainsn.api.restore != 0)
+ instruction_pointer_set(regs, cur->ainsn.api.restore);

/* restore back original saved kprobe variables and continue */
if (kcb->kprobe_status == KPROBE_REENTER) {
--
2.7.4