Merge branch 'signal-trigger'

Add signal trigger to control tracing behavior using signals.  Currently
trace-on, trace-off and finish triggers are supported only.

Closed: #340

Signed-off-by: Namhyung Kim <namhyung@gmail.com>

arch/aarch64/mcount.S

@@ -41,16 +41,9 @@ ENTRY(mcount_return)
 
 	add	x0, sp, #16
 	bl	mcount_exit
-
-	cmp	x0, #0
-	b.eq	1f
 	mov	x16, x0
-	b	2f
-
-1:	/* if finish trigger fired, use restored address */
-	ldr	x16, [sp, #40]
 
-2:	/* restore return values */
+	/* restore return values */
 	ldr	d0, [sp], #16
 	ldp	x0, x8, [sp], #16
 	/* restore frame pointer */

arch/aarch64/plthook.S

@@ -81,16 +81,9 @@ ENTRY(plthook_return)
 
 	add	x0, sp, #16
 	bl	plthook_exit
-
-	cmp	x0, #0
-	b.eq	1f
 	mov	x16, x0
-	b	2f
-
-1:	/* if finish trigger fired, use restored address */
-	ldr	x16, [sp, #40]
 
-2:	/* restore return values */
+	/* restore return values */
 	ldr	d0, [sp], #16
 	ldp	x0, x8, [sp], #16
 	/* restore frame pointer */

arch/arm/mcount.S

@@ -73,13 +73,7 @@ ENTRY(mcount_return)
 #if HAVE_ARM_HARDFP
 	vpop	{d0}
 #endif
-
-	/* if finish trigger fired, return address already updated */
-	cmp	r0, #0
-	beq	1f
-
 	/* update return address (pc) in the stack */
 	str 	r0, [sp, #12]
-1:
 	pop 	{r0-r1, lr, pc}
 END(mcount_return)

arch/arm/plthook.S

@@ -65,13 +65,7 @@ ENTRY(plthook_return)
 #ifdef HAVE_ARM_HARDFP
 	vpop {d0}
 #endif
-
-	/* if finish trigger fired, return address already updated */
-	cmp	r0, #0
-	beq	1f
-
 	/* update return address (pc) in the stack */
 	str r0, [sp, #12]
-1:
 	pop {r0-r1, lr, pc}
 END(plthook_return)

arch/i386/mcount-arch.h

@@ -29,4 +29,6 @@ unsigned long * mcount_arch_parent_location(struct symtabs *symtabs,
 #define ARCH_PLT0_SIZE  16
 #define ARCH_PLTHOOK_ADDR_OFFSET  6
 
+#define ARCH_CAN_RESTORE_PLTHOOK   1
+
 #endif /* __MCOUNT_ARCH_H__ */

arch/i386/mcount.S

@@ -43,11 +43,8 @@ ENTRY(mcount_return)
 
 	/* returns original parent address */
 	call mcount_exit
-
-	test %eax, %eax
-	jz   1f
 	movl %eax, 12(%esp)
-1:
+
 	movl 4(%esp), %eax
 	movl 8(%esp), %edx
 	add $12, %esp

arch/i386/plthook.S

@@ -56,11 +56,8 @@ ENTRY(plthook_return)
 	movl %eax, 0(%esp)
 
 	call plthook_exit
-
-	test %eax, %eax
-	jz   1f
 	movl %eax, 12(%esp)
-1:
+
 	movl 4(%esp), %eax
 	movl 8(%esp), %edx
 	add $12, %esp

arch/x86_64/mcount-arch.h

@@ -33,5 +33,6 @@ struct mcount_arch_context {
 #define ARCH_PLTHOOK_ADDR_OFFSET  6
 
 #define ARCH_SUPPORT_AUTO_RECOVER  1
+#define ARCH_CAN_RESTORE_PLTHOOK   1
 
 #endif /* MCOUNT_ARCH_H */

arch/x86_64/mcount.S

@@ -96,11 +96,8 @@ ENTRY(mcount_return)
 
 	/* returns original parent address */
 	call mcount_exit
+	movq %rax, 40(%rsp)
 
-	test  %rax, %rax
-	jz    1f
-	movq  %rax, 40(%rsp)
-1:
 	movq    0(%rsp), %rax
 	movq    8(%rsp), %rdx
 	movdqu 16(%rsp), %xmm0

arch/x86_64/plthook.S

@@ -83,11 +83,8 @@ ENTRY(plthook_return)
 	movq %rsp, %rdi
 
 	call plthook_exit
+	movq %rax, 40(%rsp)
 
-	test  %rax, %rax
-	jz    1f
-	movq  %rax, 40(%rsp)
-1:
 	movq    0(%rsp), %rax
 	movq    8(%rsp), %rdx
 	movdqu 16(%rsp), %xmm0

cmds/info.c

@@ -1096,17 +1096,17 @@ void process_uftrace_info(struct uftrace_data *handle, struct opts *opts,
 	if (info_mask & (1UL << EXIT_STATUS)) {
 		int status = info->exit_status;
 
-		if (WIFEXITED(status)) {
+		if (status == UFTRACE_EXIT_FINISHED) {
+			snprintf(buf, sizeof(buf), "terminated by finish trigger");
+		}
+		else if (WIFEXITED(status)) {
 			snprintf(buf, sizeof(buf), "exited with code: %d",
 				 WEXITSTATUS(status));
 		}
 		else if (WIFSIGNALED(status)) {
 			snprintf(buf, sizeof(buf), "terminated by signal: %d",
 				 WTERMSIG(status));
 		}
-		else if (status == UFTRACE_EXIT_FINISHED) {
-			snprintf(buf, sizeof(buf), "terminated by finish trigger");
-		}
 		else {
 			snprintf(buf, sizeof(buf), "unknown exit status: %d",
 				 status);

cmds/record.c

@@ -70,7 +70,7 @@ static bool can_use_fast_libmcount(struct opts *opts)
 	    getenv("UFTRACE_ARGUMENT")  || getenv("UFTRACE_RETVAL") ||
 	    getenv("UFTRACE_PATCH")     || getenv("UFTRACE_SCRIPT") ||
 	    getenv("UFTRACE_AUTO_ARGS") || getenv("UFTRACE_WATCH") ||
-	    getenv("UFTRACE_CALLER"))
+	    getenv("UFTRACE_CALLER")    || getenv("UFTRACE_SIGNAL"))
 		return false;
 	return true;
 }
@@ -306,6 +306,9 @@ static void setup_child_environ(struct opts *opts, int pfd,
 	if (opts->patt_type != PATT_REGEX)
 		setenv("UFTRACE_PATTERN", get_filter_pattern(opts->patt_type), 1);
 
+	if (opts->sig_trigger)
+		setenv("UFTRACE_SIGNAL", opts->sig_trigger, 1);
+
 	if (argc > 0) {
 		char *args = NULL;
 		int i;
@@ -317,6 +320,10 @@ static void setup_child_environ(struct opts *opts, int pfd,
 		free(args);
 	}
 
+	/*
+	 * ----- end of option processing -----
+	 */
+
 	libpath = get_libmcount_path(opts);
 	if (libpath == NULL)
 		pr_err_ns("cannot found libmcount.so\n");
@@ -1748,7 +1755,7 @@ static int stop_tracing(struct writer_data *wd, struct opts *opts)
 			break;
 
 		if (finish_received) {
-			ret = UFTRACE_EXIT_FINISHED;
+			status = UFTRACE_EXIT_FINISHED;
 			break;
 		}
 
@@ -1888,6 +1895,9 @@ int do_main_loop(int pfd[2], int ready, struct opts *opts, int pid)
 	wd.pipefd = pfd[0];
 	close(pfd[1]);
 
+	if (opts->sig_trigger)
+		pr_out("uftrace: install signal handlers to task %d\n", pid);
+
 	setup_writers(&wd, opts);
 	start_tracing(&wd, opts, ready);
 	close(ready);

doc/uftrace-live.md

@@ -214,6 +214,12 @@ OPTIONS
 -W, \--watch=*POINT*
 :   Add watch point to display POINT if the value is changed.  See *WATCH POINT*.
 
+\--signal=*TRG*
+:   Set trigger on selected signals rather than functions.  But there are
+    restrictions so only a few of trigger actions are support for signals.
+    The available actions are: traceon, traceoff, finish.
+    This option can be used more than once.  See *TRIGGERS*.
+
 
 FILTERS
 =======
@@ -319,10 +325,9 @@ for details.
 
 TRIGGERS
 ========
-The uftrace tool supports triggering actions on selected function calls with or
-without filters.  Currently supported triggers are `depth` (for record and
-replay) and `backtrace` (for replay only).  The BNF for trigger specifications
-is like below:
+The uftrace tool supports triggering actions on selected function calls (with or
+without filters) and/or signals.  Currently supported triggers are listed below.
+The BNF for trigger specifications is like below:
 
     <trigger>    :=  <symbol> "@" <actions>
     <actions>    :=  <action>  | <action> "," <actions>
@@ -400,6 +405,12 @@ The 'filter' and 'notrace' triggers have same effect as -F/\--filter and
 
 Triggers only work for user-level functions for now.
 
+The trigger can be used for signals as well.  This is done by signal trigger
+with \--signal option.  The syntax is similar to function trigger but only
+"trace_on", "trace_off" and "finish" trigger actions are supported.
+
+    $ uftrace live --signal 'SIGUSR1@finish' ./some-daemon
+
 
 ARGUMENTS
 =========

doc/uftrace-record.md

@@ -174,6 +174,12 @@ OPTIONS
 -W, \--watch=*POINT*
 :   Add watch point to display POINT if the value is changed.  See *WATCH POINT*.
 
+\--signal=*TRG*
+:   Set trigger on selected signals rather than functions.  But there are
+    restrictions so only a few of trigger actions are support for signals.
+    The available actions are: traceon, traceoff, finish.
+    This option can be used more than once.  See *TRIGGERS*.
+
 
 FILTERS
 =======
@@ -325,8 +331,8 @@ example will show all user functions and the (kernel) page fault handler.
 
 TRIGGERS
 ========
-The uftrace tool supports triggering actions on selected function calls with or
-without filters.  Currently supported triggers are listed below.
+The uftrace tool supports triggering actions on selected function calls (with or
+without filters) and/or signals.  Currently supported triggers are listed below.
 The BNF for trigger specification is:
 
     <trigger>    :=  <symbol> "@" <actions>
@@ -335,9 +341,8 @@ The BNF for trigger specification is:
                      "time="<time_spec> | "read="<read_spec> | "finish" |
                      "filter" | "notrace" | "recover"
     <time_spec>  :=  <num> [ <time_unit> ]
-    <time_unit>  :=  "ns" | "us" | "ms" | "s"
-    <read_spec>  :=  "proc/statm" | "page-fault" | "pmu-cycle" | "pmu-cache" |
-                     "pmu-branch"
+    <time_unit>  :=  "ns" | "nsec" | "us" | "usec" | "ms" | "msec" | "s" | "sec" | "m" | "min"
+    <read_spec>  :=  "proc/statm" | "page-fault" | "pmu-cycle" | "pmu-cache" | "pmu-branch"
 
 The `depth` trigger is to change filter depth during execution of the function.
 It can be used to apply different filter depths for different functions.
@@ -408,6 +413,12 @@ The 'filter' and 'notrace' triggers have same effect as `-F`/`--filter` and
 
 Triggers only work for user-level functions for now.
 
+The trigger can be used for signals as well.  This is done by signal trigger
+with \--signal option.  The syntax is similar to function trigger but only
+"trace_on", "trace_off" and "finish" trigger actions are supported.
+
+    $ uftrace record --signal 'SIGUSR1@finish' ./some-daemon
+
 
 ARGUMENTS
 =========

libmcount/internal.h

@@ -24,6 +24,16 @@
 #include "utils/filter.h"
 #include "utils/compiler.h"
 
+/* could be defined in mcount-arch.h */
+#ifndef  ARCH_SUPPORT_AUTO_RECOVER
+# define ARCH_SUPPORT_AUTO_RECOVER  0
+#endif
+
+/* plt_hooker has return address to hook */
+#ifndef  ARCH_CAN_RESTORE_PLTHOOK
+# define ARCH_CAN_RESTORE_PLTHOOK  0
+#endif
+
 enum filter_result {
 	FILTER_RSTACK = -1,
 	FILTER_OUT,
@@ -111,6 +121,7 @@ struct mcount_thread_data {
 	int				record_idx;
 	bool				recursion_marker;
 	bool				in_exception;
+	bool				dead;
 	unsigned long			cygprof_dummy;
 	struct mcount_ret_stack		*rstack;
 	void				*argbuf;
@@ -144,6 +155,8 @@ static inline void mcount_restore_arch_context(struct mcount_arch_context *ctx)
 
 extern TLS struct mcount_thread_data mtd;
 
+void __mcount_guard_recursion(struct mcount_thread_data *mtdp);
+void __mcount_unguard_recursion(struct mcount_thread_data *mtdp);
 bool mcount_guard_recursion(struct mcount_thread_data *mtdp);
 void mcount_unguard_recursion(struct mcount_thread_data *mtdp);
 
@@ -248,6 +261,7 @@ extern void mcount_rstack_reset_exception(struct mcount_thread_data *mtdp,
 					  unsigned long frame_addr);
 extern void mcount_auto_restore(struct mcount_thread_data *mtdp);
 extern void mcount_auto_reset(struct mcount_thread_data *mtdp);
+extern bool mcount_rstack_has_plthook(struct mcount_thread_data *mtdp);
 
 extern void prepare_shmem_buffer(struct mcount_thread_data *mtdp);
 extern void clear_shmem_buffer(struct mcount_thread_data *mtdp);