Commit 83803d97 authored by Wang Nan's avatar Wang Nan Committed by Jon Medhurst

ARM: kprobes: introduces checker

This patch introdces 'checker' to decoding phase, and calls checkers
when instruction decoding. This allows further decoding for specific
instructions.  This patch introduces a stub call of checkers in kprobe
arch_prepare_kprobe() as an example and for further expansion.
Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Reviewed-by: default avatarJon Medhurst <tixy@linaro.org>
Reviewed-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
parent 832607e7
......@@ -726,10 +726,11 @@ static void __kprobes arm_singlestep(probes_opcode_t insn,
*/
enum probes_insn __kprobes
arm_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const union decode_action *actions)
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[])
{
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,
emulate, actions);
emulate, actions, checkers);
}
......@@ -68,6 +68,7 @@ extern const union decode_item probes_decode_arm_table[];
enum probes_insn arm_probes_decode_insn(probes_opcode_t,
struct arch_probes_insn *, bool emulate,
const union decode_action *actions);
const union decode_action *actions,
const struct decode_checker *checkers[]);
#endif
......@@ -863,20 +863,22 @@ static void __kprobes thumb32_singlestep(probes_opcode_t opcode,
enum probes_insn __kprobes
thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const union decode_action *actions)
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[])
{
asi->insn_singlestep = thumb16_singlestep;
asi->insn_check_cc = thumb_check_cc;
return probes_decode_insn(insn, asi, probes_decode_thumb16_table, true,
emulate, actions);
emulate, actions, checkers);
}
enum probes_insn __kprobes
thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const union decode_action *actions)
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[])
{
asi->insn_singlestep = thumb32_singlestep;
asi->insn_check_cc = thumb_check_cc;
return probes_decode_insn(insn, asi, probes_decode_thumb32_table, true,
emulate, actions);
emulate, actions, checkers);
}
......@@ -91,9 +91,11 @@ extern const union decode_item probes_decode_thumb16_table[];
enum probes_insn __kprobes
thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const union decode_action *actions);
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[]);
enum probes_insn __kprobes
thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const union decode_action *actions);
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[]);
#endif
......@@ -342,6 +342,31 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
[DECODE_TYPE_REJECT] = sizeof(struct decode_reject)
};
static int run_checkers(const struct decode_checker *checkers[],
int action, probes_opcode_t insn,
struct arch_probes_insn *asi,
const struct decode_header *h)
{
const struct decode_checker **p;
if (!checkers)
return INSN_GOOD;
p = checkers;
while (*p != NULL) {
int retval;
probes_check_t *checker_func = (*p)[action].checker;
retval = INSN_GOOD;
if (checker_func)
retval = checker_func(insn, asi, h);
if (retval == INSN_REJECTED)
return retval;
p++;
}
return INSN_GOOD;
}
/*
* probes_decode_insn operates on data tables in order to decode an ARM
* architecture instruction onto which a kprobe has been placed.
......@@ -388,11 +413,17 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
int __kprobes
probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
const union decode_item *table, bool thumb,
bool emulate, const union decode_action *actions)
bool emulate, const union decode_action *actions,
const struct decode_checker *checkers[])
{
const struct decode_header *h = (struct decode_header *)table;
const struct decode_header *next;
bool matched = false;
/*
* @insn can be modified by decode_regs. Save its original
* value for checkers.
*/
probes_opcode_t origin_insn = insn;
if (emulate)
insn = prepare_emulated_insn(insn, asi, thumb);
......@@ -422,24 +453,41 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
}
case DECODE_TYPE_CUSTOM: {
int err;
struct decode_custom *d = (struct decode_custom *)h;
return actions[d->decoder.action].decoder(insn, asi, h);
int action = d->decoder.action;
err = run_checkers(checkers, action, origin_insn, asi, h);
if (err == INSN_REJECTED)
return INSN_REJECTED;
return actions[action].decoder(insn, asi, h);
}
case DECODE_TYPE_SIMULATE: {
int err;
struct decode_simulate *d = (struct decode_simulate *)h;
asi->insn_handler = actions[d->handler.action].handler;
int action = d->handler.action;
err = run_checkers(checkers, action, origin_insn, asi, h);
if (err == INSN_REJECTED)
return INSN_REJECTED;
asi->insn_handler = actions[action].handler;
return INSN_GOOD_NO_SLOT;
}
case DECODE_TYPE_EMULATE: {
int err;
struct decode_emulate *d = (struct decode_emulate *)h;
int action = d->handler.action;
err = run_checkers(checkers, action, origin_insn, asi, h);
if (err == INSN_REJECTED)
return INSN_REJECTED;
if (!emulate)
return actions[d->handler.action].decoder(insn,
asi, h);
return actions[action].decoder(insn, asi, h);
asi->insn_handler = actions[d->handler.action].handler;
asi->insn_handler = actions[action].handler;
set_emulated_insn(insn, asi, thumb);
return INSN_GOOD;
}
......
......@@ -314,6 +314,14 @@ union decode_action {
probes_custom_decode_t *decoder;
};
typedef enum probes_insn (probes_check_t)(probes_opcode_t,
struct arch_probes_insn *,
const struct decode_header *);
struct decode_checker {
probes_check_t *checker;
};
#define DECODE_END \
{.bits = DECODE_TYPE_END}
......@@ -402,6 +410,7 @@ probes_insn_handler_t probes_emulate_none;
int __kprobes
probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
const union decode_item *table, bool thumb, bool emulate,
const union decode_action *actions);
const union decode_action *actions,
const struct decode_checker **checkers);
#endif
......@@ -339,3 +339,5 @@ const union decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = {
[PROBES_BRANCH] = {.handler = simulate_bbl},
[PROBES_LDMSTM] = {.decoder = kprobe_decode_ldmstm}
};
const struct decode_checker *kprobes_arm_checkers[] = {NULL};
......@@ -664,3 +664,6 @@ const union decode_action kprobes_t32_actions[NUM_PROBES_T32_ACTIONS] = {
[PROBES_T32_MUL_ADD_LONG] = {
.handler = t32_emulate_rdlo12rdhi8rn16rm0_noflags},
};
const struct decode_checker *kprobes_t32_checkers[] = {NULL};
const struct decode_checker *kprobes_t16_checkers[] = {NULL};
......@@ -61,6 +61,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
kprobe_decode_insn_t *decode_insn;
const union decode_action *actions;
int is;
const struct decode_checker **checkers;
if (in_exception_text(addr))
return -EINVAL;
......@@ -74,9 +75,11 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
insn = __opcode_thumb32_compose(insn, inst2);
decode_insn = thumb32_probes_decode_insn;
actions = kprobes_t32_actions;
checkers = kprobes_t32_checkers;
} else {
decode_insn = thumb16_probes_decode_insn;
actions = kprobes_t16_actions;
checkers = kprobes_t16_checkers;
}
#else /* !CONFIG_THUMB2_KERNEL */
thumb = false;
......@@ -85,12 +88,13 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
insn = __mem_to_opcode_arm(*p->addr);
decode_insn = arm_probes_decode_insn;
actions = kprobes_arm_actions;
checkers = kprobes_arm_checkers;
#endif
p->opcode = insn;
p->ainsn.insn = tmp_insn;
switch ((*decode_insn)(insn, &p->ainsn, true, actions)) {
switch ((*decode_insn)(insn, &p->ainsn, true, actions, checkers)) {
case INSN_REJECTED: /* not supported */
return -EINVAL;
......
......@@ -37,16 +37,19 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_probes_insn *asi,
typedef enum probes_insn (kprobe_decode_insn_t)(probes_opcode_t,
struct arch_probes_insn *,
bool,
const union decode_action *);
const union decode_action *,
const struct decode_checker *[*]);
#ifdef CONFIG_THUMB2_KERNEL
extern const union decode_action kprobes_t32_actions[];
extern const union decode_action kprobes_t16_actions[];
extern const struct decode_checker *kprobes_t32_checkers[];
extern const struct decode_checker *kprobes_t16_checkers[];
#else /* !CONFIG_THUMB2_KERNEL */
extern const union decode_action kprobes_arm_actions[];
extern const struct decode_checker *kprobes_arm_checkers[];
#endif
......
......@@ -88,7 +88,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
auprobe->ixol[1] = __opcode_to_mem_arm(UPROBE_SS_ARM_INSN);
ret = arm_probes_decode_insn(insn, &auprobe->asi, false,
uprobes_probes_actions);
uprobes_probes_actions, NULL);
switch (ret) {
case INSN_REJECTED:
return -EINVAL;
......
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