Merge tag 'probes-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes updates from Masami Hiramatsu:
 "Uprobes:

   - x86/shstk: Make return uprobe work with shadow stack

   - Add uretprobe syscall which speeds up the uretprobe 10-30% faster.
     This syscall is automatically used from user-space trampolines
     which are generated by the uretprobe. If this syscall is used by
     normal user program, it will cause SIGILL. Note that this is
     currently only implemented on x86_64.

     (This also has two fixes for adjusting the syscall number to avoid
     conflict with new *attrat syscalls.)

   - uprobes/perf: fix user stack traces in the presence of pending
     uretprobe. This corrects the uretprobe's trampoline address in the
     stacktrace with correct return address

   - selftests/x86: Add a return uprobe with shadow stack test

   - selftests/bpf: Add uretprobe syscall related tests.
      - test case for register integrity check
      - test case with register changing case
      - test case for uretprobe syscall without uprobes (expected to fail)
      - test case for uretprobe with shadow stack

   - selftests/bpf: add test validating uprobe/uretprobe stack traces

   - MAINTAINERS: Add uprobes entry. This does not specify the tree but
     to clarify who maintains and reviews the uprobes

  Kprobes:

   - tracing/kprobes: Test case cleanups.

     Replace redundant WARN_ON_ONCE() + pr_warn() with WARN_ONCE() and
     remove unnecessary code from selftest

   - tracing/kprobes: Add symbol counting check when module loads.

     This checks the uniqueness of the probed symbol on modules. The
     same check has already done for kernel symbols

     (This also has a fix for build error with CONFIG_MODULES=n)

  Cleanup:

   - Add MODULE_DESCRIPTION() macros for fprobe and kprobe examples"

* tag 'probes-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  MAINTAINERS: Add uprobes entry
  selftests/bpf: Change uretprobe syscall number in uprobe_syscall test
  uprobe: Change uretprobe syscall scope and number
  tracing/kprobes: Fix build error when find_module() is not available
  tracing/kprobes: Add symbol counting check when module loads
  selftests/bpf: add test validating uprobe/uretprobe stack traces
  perf,uprobes: fix user stack traces in the presence of pending uretprobes
  tracing/kprobe: Remove cleanup code unrelated to selftest
  tracing/kprobe: Integrate test warnings into WARN_ONCE
  selftests/bpf: Add uretprobe shadow stack test
  selftests/bpf: Add uretprobe syscall call from user space test
  selftests/bpf: Add uretprobe syscall test for regs changes
  selftests/bpf: Add uretprobe syscall test for regs integrity
  selftests/x86: Add return uprobe shadow stack test
  uprobe: Add uretprobe syscall to speed up return probe
  uprobe: Wire up uretprobe system call
  x86/shstk: Make return uprobe work with shadow stack
  samples: kprobes: add missing MODULE_DESCRIPTION() macros
  fprobe: add missing MODULE_DESCRIPTION() macro

23 files changed, 1320 insertions, 92 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 11ab51646d96..655ea596b597 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -23367,6 +23367,19 @@ F:	drivers/mtd/ubi/
 F:	include/linux/mtd/ubi.h
 F:	include/uapi/mtd/ubi-user.h
 
+UPROBES
+M:	Masami Hiramatsu <mhiramat@kernel.org>
+M:	Oleg Nesterov <oleg@redhat.com>
+M:	Peter Zijlstra <peterz@infradead.org>
+L:	linux-kernel@vger.kernel.org
+L:	linux-trace-kernel@vger.kernel.org
+S:	Maintained
+F:	arch/*/include/asm/uprobes.h
+F:	arch/*/kernel/probes/uprobes.c
+F:	arch/*/kernel/uprobes.c
+F:	include/linux/uprobes.h
+F:	kernel/events/uprobes.c
+
 USB "USBNET" DRIVER FRAMEWORK
 M:	Oliver Neukum <oneukum@suse.com>
 L:	netdev@vger.kernel.org
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 097e5a18db52..83073fa3c989 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -385,6 +385,7 @@
 460	common	lsm_set_self_attr	sys_lsm_set_self_attr
 461	common	lsm_list_modules	sys_lsm_list_modules
 462 	common  mseal			sys_mseal
+467	common	uretprobe		sys_uretprobe
 
 #
 # Due to a historical design error, certain syscalls are numbered differently
diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h
index 42fee8959df7..4cb77e004615 100644
--- a/arch/x86/include/asm/shstk.h
+++ b/arch/x86/include/asm/shstk.h
@@ -21,6 +21,8 @@ unsigned long shstk_alloc_thread_stack(struct task_struct *p, unsigned long clon
 void shstk_free(struct task_struct *p);
 int setup_signal_shadow_stack(struct ksignal *ksig);
 int restore_signal_shadow_stack(void);
+int shstk_update_last_frame(unsigned long val);
+bool shstk_is_enabled(void);
 #else
 static inline long shstk_prctl(struct task_struct *task, int option,
 			       unsigned long arg2) { return -EINVAL; }
@@ -31,6 +33,8 @@ static inline unsigned long shstk_alloc_thread_stack(struct task_struct *p,
 static inline void shstk_free(struct task_struct *p) {}
 static inline int setup_signal_shadow_stack(struct ksignal *ksig) { return 0; }
 static inline int restore_signal_shadow_stack(void) { return 0; }
+static inline int shstk_update_last_frame(unsigned long val) { return 0; }
+static inline bool shstk_is_enabled(void) { return false; }
 #endif /* CONFIG_X86_USER_SHADOW_STACK */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index 6f1e9883f074..059685612362 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -577,3 +577,19 @@ long shstk_prctl(struct task_struct *task, int option, unsigned long arg2)
 		return wrss_control(true);
 	return -EINVAL;
 }
+
+int shstk_update_last_frame(unsigned long val)
+{
+	unsigned long ssp;
+
+	if (!features_enabled(ARCH_SHSTK_SHSTK))
+		return 0;
+
+	ssp = get_user_shstk_addr();
+	return write_user_shstk_64((u64 __user *)ssp, (u64)val);
+}
+
+bool shstk_is_enabled(void)
+{
+	return features_enabled(ARCH_SHSTK_SHSTK);
+}
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 6c07f6daaa22..5a952c5ea66b 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -12,6 +12,7 @@
 #include <linux/ptrace.h>
 #include <linux/uprobes.h>
 #include <linux/uaccess.h>
+#include <linux/syscalls.h>
 
 #include <linux/kdebug.h>
 #include <asm/processor.h>
@@ -308,6 +309,122 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
 }
 
 #ifdef CONFIG_X86_64
+
+asm (
+	".pushsection .rodata\n"
+	".global uretprobe_trampoline_entry\n"
+	"uretprobe_trampoline_entry:\n"
+	"pushq %rax\n"
+	"pushq %rcx\n"
+	"pushq %r11\n"
+	"movq $" __stringify(__NR_uretprobe) ", %rax\n"
+	"syscall\n"
+	".global uretprobe_syscall_check\n"
+	"uretprobe_syscall_check:\n"
+	"popq %r11\n"
+	"popq %rcx\n"
+
+	/* The uretprobe syscall replaces stored %rax value with final
+	 * return address, so we don't restore %rax in here and just
+	 * call ret.
+	 */
+	"retq\n"
+	".global uretprobe_trampoline_end\n"
+	"uretprobe_trampoline_end:\n"
+	".popsection\n"
+);
+
+extern u8 uretprobe_trampoline_entry[];
+extern u8 uretprobe_trampoline_end[];
+extern u8 uretprobe_syscall_check[];
+
+void *arch_uprobe_trampoline(unsigned long *psize)
+{
+	static uprobe_opcode_t insn = UPROBE_SWBP_INSN;
+	struct pt_regs *regs = task_pt_regs(current);
+
+	/*
+	 * At the moment the uretprobe syscall trampoline is supported
+	 * only for native 64-bit process, the compat process still uses
+	 * standard breakpoint.
+	 */
+	if (user_64bit_mode(regs)) {
+		*psize = uretprobe_trampoline_end - uretprobe_trampoline_entry;
+		return uretprobe_trampoline_entry;
+	}
+
+	*psize = UPROBE_SWBP_INSN_SIZE;
+	return &insn;
+}
+
+static unsigned long trampoline_check_ip(void)
+{
+	unsigned long tramp = uprobe_get_trampoline_vaddr();
+
+	return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry);
+}
+
+SYSCALL_DEFINE0(uretprobe)
+{
+	struct pt_regs *regs = task_pt_regs(current);
+	unsigned long err, ip, sp, r11_cx_ax[3];
+
+	if (regs->ip != trampoline_check_ip())
+		goto sigill;
+
+	err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax));
+	if (err)
+		goto sigill;
+
+	/* expose the "right" values of r11/cx/ax/sp to uprobe_consumer/s */
+	regs->r11 = r11_cx_ax[0];
+	regs->cx  = r11_cx_ax[1];
+	regs->ax  = r11_cx_ax[2];
+	regs->sp += sizeof(r11_cx_ax);
+	regs->orig_ax = -1;
+
+	ip = regs->ip;
+	sp = regs->sp;
+
+	uprobe_handle_trampoline(regs);
+
+	/*
+	 * Some of the uprobe consumers has changed sp, we can do nothing,
+	 * just return via iret.
+	 * .. or shadow stack is enabled, in which case we need to skip
+	 * return through the user space stack address.
+	 */
+	if (regs->sp != sp || shstk_is_enabled())
+		return regs->ax;
+	regs->sp -= sizeof(r11_cx_ax);
+
+	/* for the case uprobe_consumer has changed r11/cx */
+	r11_cx_ax[0] = regs->r11;
+	r11_cx_ax[1] = regs->cx;
+
+	/*
+	 * ax register is passed through as return value, so we can use
+	 * its space on stack for ip value and jump to it through the
+	 * trampoline's ret instruction
+	 */
+	r11_cx_ax[2] = regs->ip;
+	regs->ip = ip;
+
+	err = copy_to_user((void __user *)regs->sp, r11_cx_ax, sizeof(r11_cx_ax));
+	if (err)
+		goto sigill;
+
+	/* ensure sysret, see do_syscall_64() */
+	regs->r11 = regs->flags;
+	regs->cx  = regs->ip;
+
+	return regs->ax;
+
+sigill:
+	force_sig(SIGILL);
+	return -1;
+}
+
 /*
  * If arch_uprobe->insn doesn't use rip-relative addressing, return
  * immediately.  Otherwise, rewrite the instruction so that it accesses
@@ -1076,8 +1193,13 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs
 		return orig_ret_vaddr;
 
 	nleft = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize);
-	if (likely(!nleft))
+	if (likely(!nleft)) {
+		if (shstk_update_last_frame(trampoline_vaddr)) {
+			force_sig(SIGSEGV);
+			return -1;
+		}
 		return orig_ret_vaddr;
+	}
 
 	if (nleft != rasize) {
 		pr_err("return address clobbered: pid=%d, %%sp=%#lx, %%ip=%#lx\n",
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index fff820c3e93e..4bcf6754738d 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -979,6 +979,8 @@ asmlinkage long sys_lsm_list_modules(u64 __user *ids, u32 __user *size, u32 flag
 /* x86 */
 asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int on);
 
+asmlinkage long sys_uretprobe(void);
+
 /* pciconfig: alpha, arm, arm64, ia64, sparc */
 asmlinkage long sys_pciconfig_read(unsigned long bus, unsigned long dfn,
 				unsigned long off, unsigned long len,
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index f46e0ca0169c..b503fafb7fb3 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -138,6 +138,9 @@ extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check c
 extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
 extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 					 void *src, unsigned long len);
+extern void uprobe_handle_trampoline(struct pt_regs *regs);
+extern void *arch_uprobe_trampoline(unsigned long *psize);
+extern unsigned long uprobe_get_trampoline_vaddr(void);
 #else /* !CONFIG_UPROBES */
 struct uprobes_state {
 };
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 5bf6148cac2b..985a262d0f9e 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -841,8 +841,11 @@ __SYSCALL(__NR_lsm_list_modules, sys_lsm_list_modules)
 #define __NR_mseal 462
 __SYSCALL(__NR_mseal, sys_mseal)
 
+#define __NR_uretprobe 463
+__SYSCALL(__NR_uretprobe, sys_uretprobe)
+
 #undef __NR_syscalls
-#define __NR_syscalls 463
+#define __NR_syscalls 464
 
 /*
  * 32 bit systems traditionally used different
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index ad57944b6c40..8d57255e5b29 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -11,6 +11,7 @@
 #include <linux/perf_event.h>
 #include <linux/slab.h>
 #include <linux/sched/task_stack.h>
+#include <linux/uprobes.h>
 
 #include "internal.h"
 
@@ -176,13 +177,51 @@ put_callchain_entry(int rctx)
 	put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
 }
 
+static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entry,
+					       int start_entry_idx)
+{
+#ifdef CONFIG_UPROBES
+	struct uprobe_task *utask = current->utask;
+	struct return_instance *ri;
+	__u64 *cur_ip, *last_ip, tramp_addr;
+
+	if (likely(!utask || !utask->return_instances))
+		return;
+
+	cur_ip = &entry->ip[start_entry_idx];
+	last_ip = &entry->ip[entry->nr - 1];
+	ri = utask->return_instances;
+	tramp_addr = uprobe_get_trampoline_vaddr();
+
+	/*
+	 * If there are pending uretprobes for the current thread, they are
+	 * recorded in a list inside utask->return_instances; each such
+	 * pending uretprobe replaces traced user function's return address on
+	 * the stack, so when stack trace is captured, instead of seeing
+	 * actual function's return address, we'll have one or many uretprobe
+	 * trampoline addresses in the stack trace, which are not helpful and
+	 * misleading to users.
+	 * So here we go over the pending list of uretprobes, and each
+	 * encountered trampoline address is replaced with actual return
+	 * address.
+	 */
+	while (ri && cur_ip <= last_ip) {
+		if (*cur_ip == tramp_addr) {
+			*cur_ip = ri->orig_ret_vaddr;
+			ri = ri->next;
+		}
+		cur_ip++;
+	}
+#endif
+}
+
 struct perf_callchain_entry *
 get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
 		   u32 max_stack, bool crosstask, bool add_mark)
 {
 	struct perf_callchain_entry *entry;
 	struct perf_callchain_entry_ctx ctx;
-	int rctx;
+	int rctx, start_entry_idx;
 
 	entry = get_callchain_entry(&rctx);
 	if (!entry)
@@ -215,7 +254,9 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
 			if (add_mark)
 				perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
 
+			start_entry_idx = entry->nr;
 			perf_callchain_user(&ctx, regs);
+			fixup_uretprobe_trampoline_entries(entry, start_entry_idx);
 		}
 	}
 
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 2c83ba776fc7..99be2adedbc0 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1474,11 +1474,20 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 	return ret;
 }
 
+void * __weak arch_uprobe_trampoline(unsigned long *psize)
+{
+	static uprobe_opcode_t insn = UPROBE_SWBP_INSN;
+
+	*psize = UPROBE_SWBP_INSN_SIZE;
+	return &insn;
+}
+
 static struct xol_area *__create_xol_area(unsigned long vaddr)
 {
 	struct mm_struct *mm = current->mm;
-	uprobe_opcode_t insn = UPROBE_SWBP_INSN;
+	unsigned long insns_size;
 	struct xol_area *area;
+	void *insns;
 
 	area = kmalloc(sizeof(*area), GFP_KERNEL);
 	if (unlikely(!area))
@@ -1502,7 +1511,8 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
 	/* Reserve the 1st slot for get_trampoline_vaddr() */
 	set_bit(0, area->bitmap);
 	atomic_set(&area->slot_count, 1);
-	arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE);
+	insns = arch_uprobe_trampoline(&insns_size);
+	arch_uprobe_copy_ixol(area->pages[0], 0, insns, insns_size);
 
 	if (!xol_add_vma(mm, area))
 		return area;
@@ -1827,7 +1837,7 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
  *
  * Returns -1 in case the xol_area is not allocated.
  */
-static unsigned long get_trampoline_vaddr(void)
+unsigned long uprobe_get_trampoline_vaddr(void)
 {
 	struct xol_area *area;
 	unsigned long trampoline_vaddr = -1;
@@ -1878,7 +1888,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
 	if (!ri)
 		return;
 
-	trampoline_vaddr = get_trampoline_vaddr();
+	trampoline_vaddr = uprobe_get_trampoline_vaddr();
 	orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
 	if (orig_ret_vaddr == -1)
 		goto fail;
@@ -2123,7 +2133,7 @@ static struct return_instance *find_next_ret_chain(struct return_instance *ri)
 	return ri;
 }
 
-static void handle_trampoline(struct pt_regs *regs)
+void uprobe_handle_trampoline(struct pt_regs *regs)
 {
 	struct uprobe_task *utask;
 	struct return_instance *ri, *next;
@@ -2149,6 +2159,15 @@ static void handle_trampoline(struct pt_regs *regs)
 
 		instruction_pointer_set(regs, ri->orig_ret_vaddr);
 		do {
+			/* pop current instance from the stack of pending return instances,
+			 * as it's not pending anymore: we just fixed up original
+			 * instruction pointer in regs and are about to call handlers;
+			 * this allows fixup_uretprobe_trampoline_entries() to properly fix up
+			 * captured stack traces from uretprobe handlers, in which pending
+			 * trampoline addresses on the stack are replaced with correct
+			 * original return addresses
+			 */
+			utask->return_instances = ri->next;
 			if (valid)
 				handle_uretprobe_chain(ri, regs);
 			ri = free_ret_instance(ri);
@@ -2187,8 +2206,8 @@ static void handle_swbp(struct pt_regs *regs)
 	int is_swbp;
 
 	bp_vaddr = uprobe_get_swbp_addr(regs);
-	if (bp_vaddr == get_trampoline_vaddr())
-		return handle_trampoline(regs);
+	if (bp_vaddr == uprobe_get_trampoline_vaddr())
+		return uprobe_handle_trampoline(regs);
 
 	uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
 	if (!uprobe) {
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 2ef820a2d067..c00a86931f8c 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -390,3 +390,5 @@ COND_SYSCALL(setuid16);
 
 /* restartable sequence */
 COND_SYSCALL(rseq);
+
+COND_SYSCALL(uretprobe);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 16383247bdbf..61a6da808203 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -678,6 +678,21 @@ end:
 }
 
 #ifdef CONFIG_MODULES
+static int validate_module_probe_symbol(const char *modname, const char *symbol);
+
+static int register_module_trace_kprobe(struct module *mod, struct trace_kprobe *tk)
+{
+	const char *p;
+	int ret = 0;
+
+	p = strchr(trace_kprobe_symbol(tk), ':');
+	if (p)
+		ret = validate_module_probe_symbol(module_name(mod), p + 1);
+	if (!ret)
+		ret = __register_trace_kprobe(tk);
+	return ret;
+}
+
 /* Module notifier call back, checking event on the module */
 static int trace_kprobe_module_callback(struct notifier_block *nb,
 				       unsigned long val, void *data)
@@ -696,7 +711,7 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
 		if (trace_kprobe_within_module(tk, mod)) {
 			/* Don't need to check busy - this should have gone. */
 			__unregister_trace_kprobe(tk);
-			ret = __register_trace_kprobe(tk);
+			ret = register_module_trace_kprobe(mod, tk);
 			if (ret)
 				pr_warn("Failed to re-register probe %s on %s: %d\n",
 					trace_probe_name(&tk->tp),
@@ -747,17 +762,81 @@ static int count_mod_symbols(void *data, const char *name, unsigned long unused)
 	return 0;
 }
 
-static unsigned int number_of_same_symbols(char *func_name)
+static unsigned int number_of_same_symbols(const char *mod, const char *func_name)
 {
 	struct sym_count_ctx ctx = { .count = 0, .name = func_name };
 
-	kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
+	if (!mod)
+		kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count);
 
-	module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx);
+	module_kallsyms_on_each_symbol(mod, count_mod_symbols, &ctx);
 
 	return ctx.count;
 }
 
+static int validate_module_probe_symbol(const char *modname, const char *symbol)
+{
+	unsigned int count = number_of_same_symbols(modname, symbol);
+
+	if (count > 1) {
+		/*
+		 * Users should use ADDR to remove the ambiguity of
+		 * using KSYM only.
+		 */
+		return -EADDRNOTAVAIL;
+	} else if (count == 0) {
+		/*
+		 * We can return ENOENT earlier than when register the
+		 * kprobe.
+		 */
+		return -ENOENT;
+	}
+	return 0;
+}
+
+#ifdef CONFIG_MODULES
+/* Return NULL if the module is not loaded or under unloading. */
+static struct module *try_module_get_by_name(const char *name)
+{
+	struct module *mod;
+
+	rcu_read_lock_sched();
+	mod = find_module(name);
+	if (mod && !try_module_get(mod))
+		mod = NULL;
+	rcu_read_unlock_sched();
+
+	return mod;
+}
+#else
+#define try_module_get_by_name(name)	(NULL)
+#endif
+
+static int validate_probe_symbol(char *symbol)
+{
+	struct module *mod = NULL;
+	char *modname = NULL, *p;
+	int ret = 0;
+
+	p = strchr(symbol, ':');
+	if (p) {
+		modname = symbol;
+		symbol = p + 1;
+		*p = '\0';
+		mod = try_module_get_by_name(modname);
+		if (!mod)
+			goto out;
+	}
+
+	ret = validate_module_probe_symbol(modname, symbol);
+out:
+	if (p)
+		*p = ':';
+	if (mod)
+		module_put(mod);
+	return ret;
+}
+
 static int trace_kprobe_entry_handler(struct kretprobe_instance *ri,
 				      struct pt_regs *regs);
 
@@ -881,6 +960,14 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 			trace_probe_log_err(0, BAD_PROBE_ADDR);
 			goto parse_error;
 		}
+		ret = validate_probe_symbol(symbol);
+		if (ret) {
+			if (ret == -EADDRNOTAVAIL)
+				trace_probe_log_err(0, NON_UNIQ_SYMBOL);
+			else
+				trace_probe_log_err(0, BAD_PROBE_ADDR);
+			goto parse_error;
+		}
 		if (is_return)
 			ctx.flags |= TPARG_FL_RETURN;
 		ret = kprobe_on_func_entry(NULL, symbol, offset);
@@ -893,31 +980,6 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 		}
 	}
 
-	if (symbol && !strchr(symbol, ':')) {
-		unsigned int count;
-
-		count = number_of_same_symbols(symbol);
-		if (count > 1) {
-			/*
-			 * Users should use ADDR to remove the ambiguity of
-			 * using KSYM only.
-			 */
-			trace_probe_log_err(0, NON_UNIQ_SYMBOL);
-			ret = -EADDRNOTAVAIL;
-
-			goto error;
-		} else if (count == 0) {
-			/*
-			 * We can return ENOENT earlier than when register the
-			 * kprobe.
-			 */
-			trace_probe_log_err(0, BAD_PROBE_ADDR);
-			ret = -ENOENT;
-
-			goto error;
-		}
-	}
-
 	trace_probe_log_set_index(0);
 	if (event) {
 		ret = traceprobe_parse_event_name(&event, &group, gbuf,
@@ -1835,21 +1897,9 @@ create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
 	char *event;
 
 	if (func) {
-		unsigned int count;
-
-		count = number_of_same_symbols(func);
-		if (count > 1)
-			/*
-			 * Users should use addr to remove the ambiguity of
-			 * using func only.
-			 */
-			return ERR_PTR(-EADDRNOTAVAIL);
-		else if (count == 0)
-			/*
-			 * We can return ENOENT earlier than when register the
-			 * kprobe.
-			 */
-			return ERR_PTR(-ENOENT);
+		ret = validate_probe_symbol(func);
+		if (ret)
+			return ERR_PTR(ret);
 	}
 
 	/*
@@ -2023,19 +2073,16 @@ static __init int kprobe_trace_self_tests_init(void)
 	pr_info("Testing kprobe tracing: ");
 
 	ret = create_or_delete_trace_kprobe("p:testprobe kprobe_trace_selftest_target $stack $stack0 +0($stack)");
-	if (WARN_ON_ONCE(ret)) {
-		pr_warn("error on probing function entry.\n");
+	if (WARN_ONCE(ret, "error on probing function entry.")) {
 		warn++;
 	} else {
 		/* Enable trace point */
 		tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
-		if (WARN_ON_ONCE(tk == NULL)) {
-			pr_warn("error on getting new probe.\n");
+		if (WARN_ONCE(tk == NULL, "error on probing function entry.")) {
 			warn++;
 		} else {
 			file = find_trace_probe_file(tk, top_trace_array());
-			if (WARN_ON_ONCE(file == NULL)) {
-				pr_warn("error on getting probe file.\n");
+			if (WARN_ONCE(file == NULL, "error on getting probe file.")) {
 				warn++;
 			} else
 				enable_trace_kprobe(
@@ -2044,19 +2091,16 @@ static __init int kprobe_trace_self_tests_init(void)
 	}
 
 	ret = create_or_delete_trace_kprobe("r:testprobe2 kprobe_trace_selftest_target $retval");
-	if (WARN_ON_ONCE(ret)) {
-		pr_warn("error on probing function return.\n");
+	if (WARN_ONCE(ret, "error on probing function return.")) {
 		warn++;
 	} else {
 		/* Enable trace point */
 		tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
-		if (WARN_ON_ONCE(tk == NULL)) {
-			pr_warn("error on getting 2nd new probe.\n");
+		if (WARN_ONCE(tk == NULL, "error on getting 2nd new probe.")) {
 			warn++;
 		} else {
 			file = find_trace_probe_file(tk, top_trace_array());
-			if (WARN_ON_ONCE(file == NULL)) {
-				pr_warn("error on getting probe file.\n");
+			if (WARN_ONCE(file == NULL, "error on getting probe file.")) {
 				warn++;
 			} else
 				enable_trace_kprobe(
@@ -2079,18 +2123,15 @@ static __init int kprobe_trace_self_tests_init(void)
 
 	/* Disable trace points before removing it */
 	tk = find_trace_kprobe("testprobe", KPROBE_EVENT_SYSTEM);
-	if (WARN_ON_ONCE(tk == NULL)) {
-		pr_warn("error on getting test probe.\n");
+	if (WARN_ONCE(tk == NULL, "error on getting test probe.")) {
 		warn++;
 	} else {
-		if (trace_kprobe_nhit(tk) != 1) {
-			pr_warn("incorrect number of testprobe hits\n");
+		if (WARN_ONCE(trace_kprobe_nhit(tk) != 1,
+				 "incorrect number of testprobe hits."))
 			warn++;
-		}
 
 		file = find_trace_probe_file(tk, top_trace_array());
-		if (WARN_ON_ONCE(file == NULL)) {
-			pr_warn("error on getting probe file.\n");
+		if (WARN_ONCE(file == NULL, "error on getting probe file.")) {
 			warn++;
 		} else
 			disable_trace_kprobe(
@@ -2098,18 +2139,15 @@ static __init int kprobe_trace_self_tests_init(void)
 	}
 
 	tk = find_trace_kprobe("testprobe2", KPROBE_EVENT_SYSTEM);
-	if (WARN_ON_ONCE(tk == NULL)) {
-		pr_warn("error on getting 2nd test probe.\n");
+	if (WARN_ONCE(tk == NULL, "error on getting 2nd test probe.")) {
 		warn++;
 	} else {
-		if (trace_kprobe_nhit(tk) != 1) {
-			pr_warn("incorrect number of testprobe2 hits\n");
+		if (WARN_ONCE(trace_kprobe_nhit(tk) != 1,
+				 "incorrect number of testprobe2 hits."))
 			warn++;
-		}
 
 		file = find_trace_probe_file(tk, top_trace_array());
-		if (WARN_ON_ONCE(file == NULL)) {
-			pr_warn("error on getting probe file.\n");
+		if (WARN_ONCE(file == NULL, "error on getting probe file.")) {
 			warn++;
 		} else
 			disable_trace_kprobe(
@@ -2117,23 +2155,15 @@ static __init int kprobe_trace_self_tests_init(void)
 	}
 
 	ret = create_or_delete_trace_kprobe("-:testprobe");
-	if (WARN_ON_ONCE(ret)) {
-		pr_warn("error on deleting a probe.\n");
+	if (WARN_ONCE(ret, "error on deleting a probe."))
 		warn++;
-	}
 
 	ret = create_or_delete_trace_kprobe("-:testprobe2");
-	if (WARN_ON_ONCE(ret)) {
-		pr_warn("error on deleting a probe.\n");
+	if (WARN_ONCE(ret, "error on deleting a probe."))
 		warn++;
-	}
+
 
 end:
-	ret = dyn_events_release_all(&trace_kprobe_ops);
-	if (WARN_ON_ONCE(ret)) {
-		pr_warn("error on cleaning up probes.\n");
-		warn++;
-	}
 	/*
 	 * Wait for the optimizer work to finish. Otherwise it might fiddle
 	 * with probes in already freed __init text.
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index 64e715e7ed11..0a50b05add96 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -150,4 +150,5 @@ static void __exit fprobe_exit(void)
 
 module_init(fprobe_init)
 module_exit(fprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of fprobe");
 MODULE_LICENSE("GPL");
diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index ef44c614c6d9..53ec6c8b8c40 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -125,4 +125,5 @@ static void __exit kprobe_exit(void)
 
 module_init(kprobe_init)
 module_exit(kprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of kprobes");
 MODULE_LICENSE("GPL");
diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
index ed79fd3d48fb..65d6dcafd742 100644
--- a/samples/kprobes/kretprobe_example.c
+++ b/samples/kprobes/kretprobe_example.c
@@ -104,4 +104,5 @@ static void __exit kretprobe_exit(void)
 
 module_init(kretprobe_init)
 module_exit(kretprobe_exit)
+MODULE_DESCRIPTION("sample kernel module showing the use of return probes");
 MODULE_LICENSE("GPL");
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 8a63a9913495..6f7f22ac9da5 100644
--- a/tools/include/linux/co