Add a test to verify that the registers passed in pt_regs on kprobe
(trap), optprobe (jump) and kprobe_on_ftrace (ftrace_caller) are
accurate. The tests are exercized if KPROBES_SANITY_TEST is enabled.
Implemented for powerpc64. Other architectures will have to implement
the relevant arch_* helpers and define HAVE_KPROBES_REGS_SANITY_TEST.
Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/kprobes.h | 4 +
arch/powerpc/lib/Makefile | 3 +-
arch/powerpc/lib/test_kprobe_regs.S | 62 ++++++++++++
arch/powerpc/lib/test_kprobes.c | 115 ++++++++++++++++++++++
include/linux/kprobes.h | 11 +++
kernel/test_kprobes.c | 183 ++++++++++++++++++++++++++++++++++++
6 files changed, 377 insertions(+), 1 deletion(-)
create mode 100644 arch/powerpc/lib/test_kprobe_regs.S
create mode 100644 arch/powerpc/lib/test_kprobes.c
diff --git a/arch/powerpc/include/asm/kprobes.h
b/arch/powerpc/include/asm/kprobes.h
index 566da372e02b..10c91d3132a1 100644
--- a/arch/powerpc/include/asm/kprobes.h
+++ b/arch/powerpc/include/asm/kprobes.h
@@ -124,6 +124,10 @@ static inline int skip_singlestep(struct kprobe *p, struct
pt_regs *regs,
return 0;
}
#endif
+#if defined(CONFIG_KPROBES_SANITY_TEST) && defined(CONFIG_PPC64)
+#define HAVE_KPROBES_REGS_SANITY_TEST
+void arch_kprobe_regs_set_ptregs(struct pt_regs *regs);
+#endif
#else
static inline int kprobe_handler(struct pt_regs *regs) { return 0; }
static inline int kprobe_post_handler(struct pt_regs *regs) { return 0; }
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 3c3146ba62da..8a0bb8e20179 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -27,7 +27,8 @@ obj64-y += copypage_64.o copyuser_64.o mem_64.o
hweight_64.o \
obj64-$(CONFIG_SMP) += locks.o
obj64-$(CONFIG_ALTIVEC) += vmx-helper.o
-obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
+obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o test_kprobe_regs.o \
+ test_kprobes.o
obj-y += checksum_$(BITS).o checksum_wrappers.o
diff --git a/arch/powerpc/lib/test_kprobe_regs.S
b/arch/powerpc/lib/test_kprobe_regs.S
new file mode 100644
index 000000000000..4e95eca6dcd3
--- /dev/null
+++ b/arch/powerpc/lib/test_kprobe_regs.S
@@ -0,0 +1,62 @@
+/*
+ * test_kprobe_regs: architectural helpers for validating pt_regs
+ * received on a kprobe.
+ *
+ * Copyright 2017 Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
+ * IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/ptrace.h>
+
+_GLOBAL(arch_kprobe_regs_function)
+ mflr r0
+ std r0, LRSAVE(r1)
+ stdu r1, -SWITCH_FRAME_SIZE(r1)
+
+ /* Tell pre handler about our pt_regs location */
+ addi r3, r1, STACK_FRAME_OVERHEAD
+ bl arch_kprobe_regs_set_ptregs
+
+ /* Load back our true LR */
+ ld r0, (SWITCH_FRAME_SIZE + LRSAVE)(r1)
+ mtlr r0
+
+ /* Save all SPRs that we care about */
+ mfctr r0
+ std r0, _CTR(r1)
+ mflr r0
+ std r0, _LINK(r1)
+ mfspr r0, SPRN_XER
+ std r0, _XER(r1)
+ mfcr r0
+ std r0, _CCR(r1)
+
+ /* Now, save all GPRs */
+ SAVE_2GPRS(0, r1)
+ SAVE_10GPRS(2, r1)
+ SAVE_10GPRS(12, r1)
+ SAVE_10GPRS(22, r1)
+
+ /* We're now ready to be probed */
+.global arch_kprobe_regs_probepoint
+arch_kprobe_regs_probepoint:
+ nop
+
+#ifdef CONFIG_KPROBES_ON_FTRACE
+ /* Let's also test KPROBES_ON_FTRACE */
+ bl kprobe_regs_kp_on_ftrace_target
+ nop
+#endif
+
+ /* All done */
+ addi r1, r1, SWITCH_FRAME_SIZE
+ ld r0, LRSAVE(r1)
+ mtlr r0
+ blr
diff --git a/arch/powerpc/lib/test_kprobes.c b/arch/powerpc/lib/test_kprobes.c
new file mode 100644
index 000000000000..23f7a7ffcdd6
--- /dev/null
+++ b/arch/powerpc/lib/test_kprobes.c
@@ -0,0 +1,115 @@
+/*
+ * test_kprobes: architectural helpers for validating pt_regs
+ * received on a kprobe.
+ *
+ * Copyright 2017 Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
+ * IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#define pr_fmt(fmt) "Kprobe smoke test (regs): " fmt
+
+#include <asm/ptrace.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+
+static struct pt_regs *r;
+
+void arch_kprobe_regs_set_ptregs(struct pt_regs *regs)
+{
+ r = regs;
+}
+
+static int validate_regs(struct kprobe *p, struct pt_regs *regs,
+ int kp_on_ftrace, int post_handler)
+{
+ int i, ret = 1;
+
+ if (!r) {
+ pr_err("pt_regs not setup!\n");
+ return 0;
+ }
+
+ if (regs->gpr[1] + STACK_FRAME_OVERHEAD != (unsigned long)r) {
+ /* We'll continue since this may just indicate an incorrect r1
*/
+ pr_err("pt_regs pointer/r1 doesn't point where we expect!\n");
+ ret = 0;
+ }
+
+ for (i = 0; i < 32; i++) {
+ /* KPROBES_ON_FTRACE may have stomped r0 in the prologue */
+ if (r->gpr[i] != regs->gpr[i] && (!kp_on_ftrace || i != 0)) {
+ pr_err("gpr[%d] expected: 0x%lx, received: 0x%lx\n",
+ i, r->gpr[i], regs->gpr[i]);
+ ret = 0;
+ }
+ }
+
+ if (r->ctr != regs->ctr) {
+ pr_err("ctr expected: 0x%lx, received: 0x%lx\n",
+ r->ctr, regs->ctr);
+ ret = 0;
+ }
+
+ if (r->link != regs->link && !kp_on_ftrace) {
+ pr_err("link expected: 0x%lx, received: 0x%lx\n",
+ r->link, regs->link);
+ ret = 0;
+ }
+
+ /* KPROBES_ON_FTRACE *must* have clobbered link */
+ if (r->link == regs->link && kp_on_ftrace) {
+ pr_err("link register not clobbered for KPROBES_ON_FTRACE!\n");
+ ret = 0;
+ }
+
+ if (r->xer != regs->xer) {
+ pr_err("xer expected: 0x%lx, received: 0x%lx\n",
+ r->xer, regs->xer);
+ ret = 0;
+ }
+
+ if (r->ccr != regs->ccr) {
+ pr_err("ccr expected: 0x%lx, received: 0x%lx\n",
+ r->ccr, regs->ccr);
+ ret = 0;
+ }
+
+ if (!post_handler && regs->nip != (unsigned long)p->addr) {
+ pr_err("nip expected: 0x%lx, received: 0x%lx\n",
+ (unsigned long)p->addr, regs->nip);
+ ret = 0;
+ }
+
+ if (post_handler &&
+ regs->nip != (unsigned long)p->addr + sizeof(kprobe_opcode_t)) {
+ pr_err("post_handler: nip expected: 0x%lx, received: 0x%lx\n",
+ (unsigned long)p->addr +
sizeof(kprobe_opcode_t),
+ regs->nip);
+ ret = 0;
+ }
+
+ return ret;
+}
+
+int arch_kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return validate_regs(p, regs, 0, 0);
+}
+
+int arch_kprobe_regs_post_handler(struct kprobe *p, struct pt_regs *regs,
+ unsigned long flags)
+{
+ return validate_regs(p, regs, 0, 1);
+}
+
+#ifdef CONFIG_KPROBES_ON_FTRACE
+int arch_kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ return validate_regs(p, regs, 1, 0);
+}
+#endif
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 541df0b5b815..adfbb5b27acd 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -253,6 +253,17 @@ static inline void kretprobe_assert(struct
kretprobe_instance *ri,
#ifdef CONFIG_KPROBES_SANITY_TEST
extern int init_test_probes(void);
+#ifdef HAVE_KPROBES_REGS_SANITY_TEST
+extern void arch_kprobe_regs_function(void);
+extern void arch_kprobe_regs_probepoint(void);
+extern int arch_kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs
*regs);
+extern int arch_kprobe_regs_post_handler(struct kprobe *p, struct pt_regs
*regs,
+ unsigned long flags);
+#ifdef CONFIG_KPROBES_ON_FTRACE
+extern void kprobe_regs_kp_on_ftrace_target(void);
+extern int arch_kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs
*regs);
+#endif
+#endif
#else
static inline int init_test_probes(void)
{
diff --git a/kernel/test_kprobes.c b/kernel/test_kprobes.c
index 0dbab6d1acb4..92011726cc69 100644
--- a/kernel/test_kprobes.c
+++ b/kernel/test_kprobes.c
@@ -19,6 +19,7 @@
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/random.h>
+#include <linux/workqueue.h>
#define div_factor 3
@@ -334,6 +335,166 @@ static int test_kretprobes(void)
}
#endif /* CONFIG_KRETPROBES */
+#ifdef HAVE_KPROBES_REGS_SANITY_TEST
+static int kprobe_regs_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ /* architectural helper returns 0 if validation fails */
+ preh_val = arch_kprobe_regs_pre_handler(p, regs);
+ return 0;
+}
+
+static void kprobe_regs_post_handler(struct kprobe *p, struct pt_regs *regs,
+ unsigned long flags)
+{
+ posth_val = arch_kprobe_regs_post_handler(p, regs, flags);
+}
+
+static struct kprobe kpr = {
+ .symbol_name = "arch_kprobe_regs_probepoint",
+ .pre_handler = kprobe_regs_pre_handler,
+ .post_handler = kprobe_regs_post_handler,
+};
+
+static int test_kprobe_regs(void)
+{
+ int ret;
+ kprobe_opcode_t *addr;
+
+ preh_val = 0;
+ posth_val = 0;
+
+ ret = register_kprobe(&kpr);
+ if (ret < 0) {
+ pr_err("register_kprobe returned %d\n", ret);
+ return ret;
+ }
+
+ /* Let's see if this probe was optimized */
+ addr = kprobe_lookup_name(kpr.symbol_name, 0);
+ if (addr && *addr != BREAKPOINT_INSTRUCTION) {
+ pr_err("kprobe with post_handler optimized\n");
+ unregister_kprobe(&kpr);
+ return -1;
+ }
+
+ arch_kprobe_regs_function();
+ unregister_kprobe(&kpr);
+
+ if (preh_val == 0) {
+ pr_err("kprobe pre_handler regs validation failed\n");
+ handler_errors++;
+ }
+
+ if (posth_val == 0) {
+ pr_err("kprobe post_handler not called\n");
+ handler_errors++;
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_KPROBES_ON_FTRACE
+void kprobe_regs_kp_on_ftrace_target(void)
+{
+ posth_val = preh_val + div_factor;
+}
+
+static int kp_on_ftrace_pre_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ /* architectural helper returns 0 if validation fails */
+ preh_val = arch_kp_on_ftrace_pre_handler(p, regs);
+ return 0;
+}
+
+static struct kprobe kprf = {
+ .symbol_name = "kprobe_regs_kp_on_ftrace_target",
+ .pre_handler = kp_on_ftrace_pre_handler,
+};
+
+static int test_kp_on_ftrace_regs(void)
+{
+ int ret;
+
+ preh_val = 0;
+
+ ret = register_kprobe(&kprf);
+ if (ret < 0) {
+ pr_err("register_kprobe returned %d\n", ret);
+ return ret;
+ }
+
+ arch_kprobe_regs_function();
+ unregister_kprobe(&kprf);
+
+ if (preh_val == 0) {
+ pr_err("kp_on_ftrace pre_handler regs validation failed\n");
+ handler_errors++;
+ }
+
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_OPTPROBES
+static void test_optprobe_regs(struct work_struct *work);
+static DECLARE_DELAYED_WORK(test_optprobe_regs_work, test_optprobe_regs);
+int kprobe_registered;
+
+static struct kprobe kpor = {
+ .symbol_name = "arch_kprobe_regs_probepoint",
+ .pre_handler = kprobe_regs_pre_handler,
+};
+
+static void test_optprobe_regs_setup(void)
+{
+ int ret;
+
+ ret = register_kprobe(&kpor);
+ if (ret < 0) {
+ pr_err("register_kprobe returned %d\n", ret);
+ return;
+ }
+
+ kprobe_registered = 1;
+}
+
+static void test_optprobe_regs(struct work_struct *work)
+{
+ kprobe_opcode_t *addr;
+
+ if (!kprobe_registered) {
+ errors++;
+ goto summary;
+ }
+
+ /* Let's see if this probe was optimized */
+ addr = kprobe_lookup_name(kpor.symbol_name, 0);
+ if (addr && *addr == BREAKPOINT_INSTRUCTION) {
+ pr_info("kprobe not optimized yet... skipping optprobe test\n");
+ unregister_kprobe(&kpor);
+ goto summary;
+ }
+
+ preh_val = 0;
+ arch_kprobe_regs_function();
+ unregister_kprobe(&kpor);
+
+ if (preh_val == 0) {
+ pr_err("optprobe pre_handler regs validation failed\n");
+ handler_errors++;
+ }
+
+summary:
+ if (errors)
+ pr_err("BUG: %d out of %d tests failed\n", errors, num_tests);
+ else if (handler_errors)
+ pr_err("BUG: %d error(s) running handlers\n", handler_errors);
+ else
+ pr_info("passed successfully\n");
+}
+#endif
+#endif
+
int init_test_probes(void)
{
int ret;
@@ -378,12 +539,34 @@ int init_test_probes(void)
errors++;
#endif /* CONFIG_KRETPROBES */
+#ifdef HAVE_KPROBES_REGS_SANITY_TEST
+ num_tests++;
+ ret = test_kprobe_regs();
+ if (ret < 0)
+ errors++;
+
+#ifdef CONFIG_KPROBES_ON_FTRACE
+ num_tests++;
+ ret = test_kp_on_ftrace_regs();
+ if (ret < 0)
+ errors++;
+#endif
+
+#ifdef CONFIG_OPTPROBES
+ num_tests++;
+ test_optprobe_regs_setup();
+ schedule_delayed_work(&test_optprobe_regs_work, 10);
+#endif
+#endif
+
+#if !defined(HAVE_KPROBES_REGS_SANITY_TEST) || !defined(CONFIG_OPTPROBES)
if (errors)
pr_err("BUG: %d out of %d tests failed\n", errors, num_tests);
else if (handler_errors)
pr_err("BUG: %d error(s) running handlers\n", handler_errors);
else
pr_info("passed successfully\n");
+#endif
return 0;
}
--
2.12.2
