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sh: kprobes SMP support.
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Presently kprobes support relies on several saved opcode variables for
saving and restoring state, without any specific locking. This is
inherently racy on SMP, and given that we already use per-CPU variables
for everything else, convert these over too.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
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Paul Mundt committed Jun 14, 2010
1 parent da28c59 commit 57fcfdf
Showing 1 changed file with 50 additions and 50 deletions.
100 changes: 50 additions & 50 deletions arch/sh/kernel/kprobes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,9 @@
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

static struct kprobe saved_current_opcode;
static struct kprobe saved_next_opcode;
static struct kprobe saved_next_opcode2;
static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);

#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
Expand Down Expand Up @@ -102,16 +102,21 @@ int __kprobes kprobe_handle_illslot(unsigned long pc)

void __kprobes arch_remove_kprobe(struct kprobe *p)
{
if (saved_next_opcode.addr != 0x0) {
struct kprobe *saved = &__get_cpu_var(saved_next_opcode);

if (saved->addr) {
arch_disarm_kprobe(p);
arch_disarm_kprobe(&saved_next_opcode);
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;

if (saved_next_opcode2.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode2);
saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;
arch_disarm_kprobe(saved);

saved->addr = NULL;
saved->opcode = 0;

saved = &__get_cpu_var(saved_next_opcode2);
if (saved->addr) {
arch_disarm_kprobe(saved);

saved->addr = NULL;
saved->opcode = 0;
}
}
}
Expand Down Expand Up @@ -141,57 +146,59 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
*/
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t *addr = NULL;
saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
addr = saved_current_opcode.addr;
__get_cpu_var(saved_current_opcode).addr = (kprobe_opcode_t *)regs->pc;

if (p != NULL) {
struct kprobe *op1, *op2;

arch_disarm_kprobe(p);

op1 = &__get_cpu_var(saved_next_opcode);
op2 = &__get_cpu_var(saved_next_opcode2);

if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
saved_next_opcode.addr =
(kprobe_opcode_t *) regs->regs[reg_nr];
op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
} else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
unsigned long disp = (p->opcode & 0x0FFF);
saved_next_opcode.addr =
op1->addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);

} else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
saved_next_opcode.addr =
op1->addr =
(kprobe_opcode_t *) (regs->pc + 4 +
regs->regs[reg_nr]);

} else if (OPCODE_RTS(p->opcode)) {
saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr;
op1->addr = (kprobe_opcode_t *) regs->pr;

} else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
unsigned long disp = (p->opcode & 0x00FF);
/* case 1 */
saved_next_opcode.addr = p->addr + 1;
op1->addr = p->addr + 1;
/* case 2 */
saved_next_opcode2.addr =
op2->addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
arch_arm_kprobe(&saved_next_opcode2);
op2->opcode = *(op2->addr);
arch_arm_kprobe(op2);

} else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
unsigned long disp = (p->opcode & 0x00FF);
/* case 1 */
saved_next_opcode.addr = p->addr + 2;
op1->addr = p->addr + 2;
/* case 2 */
saved_next_opcode2.addr =
op2->addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
arch_arm_kprobe(&saved_next_opcode2);
op2->opcode = *(op2->addr);
arch_arm_kprobe(op2);

} else {
saved_next_opcode.addr = p->addr + 1;
op1->addr = p->addr + 1;
}

saved_next_opcode.opcode = *(saved_next_opcode.addr);
arch_arm_kprobe(&saved_next_opcode);
op1->opcode = *(op1->addr);
arch_arm_kprobe(op1);
}
}

Expand Down Expand Up @@ -376,21 +383,23 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
cur->post_handler(cur, regs, 0);
}

if (saved_next_opcode.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode);
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;
p = &__get_cpu_var(saved_next_opcode);
if (p->addr) {
arch_disarm_kprobe(p);
p->addr = NULL;
p->opcode = 0;

addr = saved_current_opcode.addr;
saved_current_opcode.addr = 0x0;
addr = __get_cpu_var(saved_current_opcode).addr;
__get_cpu_var(saved_current_opcode).addr = NULL;

p = get_kprobe(addr);
arch_arm_kprobe(p);

if (saved_next_opcode2.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode2);
saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;
p = &__get_cpu_var(saved_next_opcode2);
if (p->addr) {
arch_disarm_kprobe(p);
p->addr = NULL;
p->opcode = 0;
}
}

Expand Down Expand Up @@ -572,14 +581,5 @@ static struct kprobe trampoline_p = {

int __init arch_init_kprobes(void)
{
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;

saved_current_opcode.addr = 0x0;
saved_current_opcode.opcode = 0x0;

saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;

return register_kprobe(&trampoline_p);
}

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