Merge tag 'for_linus-3.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb

Pull KGDB/KDB regression fixes from Jason Wessel:
 - Fix a Smatch warning that appeared in the 3.4 merge window
 - Fix kgdb test suite with SMP for all archs without HW single stepping
 - Fix kgdb sw breakpoints with CONFIG_DEBUG_RODATA=y limitations on x86
 - Fix oops on kgdb test suite with CONFIG_DEBUG_RODATA
 - Fix kgdb test suite with SMP for all archs with HW single stepping

* tag 'for_linus-3.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
  x86,kgdb: Fix DEBUG_RODATA limitation using text_poke()
  kgdb,debug_core: pass the breakpoint struct instead of address and memory
  kgdbts: (2 of 2) fix single step awareness to work correctly with SMP
  kgdbts: (1 of 2) fix single step awareness to work correctly with SMP
  kgdbts: Fix kernel oops with CONFIG_DEBUG_RODATA
  kdb: Fix smatch warning on dbg_io_ops->is_console

Author: torvalds

arch/x86/kernel/kgdb.c

@@ -43,6 +43,8 @@
 #include <linux/smp.h>
 #include <linux/nmi.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/uaccess.h>
+#include <linux/memory.h>
 
 #include <asm/debugreg.h>
 #include <asm/apicdef.h>
@@ -741,6 +743,64 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 	regs->ip = ip;
 }
 
+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
+{
+	int err;
+	char opc[BREAK_INSTR_SIZE];
+
+	bpt->type = BP_BREAKPOINT;
+	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+				BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+	err = probe_kernel_write((char *)bpt->bpt_addr,
+				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
+#ifdef CONFIG_DEBUG_RODATA
+	if (!err)
+		return err;
+	/*
+	 * It is safe to call text_poke() because normal kernel execution
+	 * is stopped on all cores, so long as the text_mutex is not locked.
+	 */
+	if (mutex_is_locked(&text_mutex))
+		return -EBUSY;
+	text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
+		  BREAK_INSTR_SIZE);
+	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+	if (err)
+		return err;
+	if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
+		return -EINVAL;
+	bpt->type = BP_POKE_BREAKPOINT;
+#endif /* CONFIG_DEBUG_RODATA */
+	return err;
+}
+
+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
+{
+#ifdef CONFIG_DEBUG_RODATA
+	int err;
+	char opc[BREAK_INSTR_SIZE];
+
+	if (bpt->type != BP_POKE_BREAKPOINT)
+		goto knl_write;
+	/*
+	 * It is safe to call text_poke() because normal kernel execution
+	 * is stopped on all cores, so long as the text_mutex is not locked.
+	 */
+	if (mutex_is_locked(&text_mutex))
+		goto knl_write;
+	text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
+	err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+	if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
+		goto knl_write;
+	return err;
+knl_write:
+#endif /* CONFIG_DEBUG_RODATA */
+	return probe_kernel_write((char *)bpt->bpt_addr,
+				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
+}
+
 struct kgdb_arch arch_kgdb_ops = {
 	/* Breakpoint instruction: */
 	.gdb_bpt_instr		= { 0xcc },

drivers/misc/kgdbts.c

@@ -134,12 +134,17 @@ static int force_hwbrks;
 static int hwbreaks_ok;
 static int hw_break_val;
 static int hw_break_val2;
+static int cont_instead_of_sstep;
+static unsigned long cont_thread_id;
+static unsigned long sstep_thread_id;
 #if defined(CONFIG_ARM) || defined(CONFIG_MIPS) || defined(CONFIG_SPARC)
 static int arch_needs_sstep_emulation = 1;
 #else
 static int arch_needs_sstep_emulation;
 #endif
+static unsigned long cont_addr;
 static unsigned long sstep_addr;
+static int restart_from_top_after_write;
 static int sstep_state;
 
 /* Storage for the registers, in GDB format. */
@@ -187,7 +192,8 @@ static int kgdbts_unreg_thread(void *ptr)
 	 */
 	while (!final_ack)
 		msleep_interruptible(1500);
-
+	/* Pause for any other threads to exit after final ack. */
+	msleep_interruptible(1000);
 	if (configured)
 		kgdb_unregister_io_module(&kgdbts_io_ops);
 	configured = 0;
@@ -211,7 +217,7 @@ static unsigned long lookup_addr(char *arg)
 	if (!strcmp(arg, "kgdbts_break_test"))
 		addr = (unsigned long)kgdbts_break_test;
 	else if (!strcmp(arg, "sys_open"))
-		addr = (unsigned long)sys_open;
+		addr = (unsigned long)do_sys_open;
 	else if (!strcmp(arg, "do_fork"))
 		addr = (unsigned long)do_fork;
 	else if (!strcmp(arg, "hw_break_val"))
@@ -283,6 +289,16 @@ static void hw_break_val_write(void)
 	hw_break_val++;
 }
 
+static int get_thread_id_continue(char *put_str, char *arg)
+{
+	char *ptr = &put_str[11];
+
+	if (put_str[1] != 'T' || put_str[2] != '0')
+		return 1;
+	kgdb_hex2long(&ptr, &cont_thread_id);
+	return 0;
+}
+
 static int check_and_rewind_pc(char *put_str, char *arg)
 {
 	unsigned long addr = lookup_addr(arg);
@@ -299,13 +315,21 @@ static int check_and_rewind_pc(char *put_str, char *arg)
 	if (addr + BREAK_INSTR_SIZE == ip)
 		offset = -BREAK_INSTR_SIZE;
 #endif
-	if (strcmp(arg, "silent") && ip + offset != addr) {
+
+	if (arch_needs_sstep_emulation && sstep_addr &&
+	    ip + offset == sstep_addr &&
+	    ((!strcmp(arg, "sys_open") || !strcmp(arg, "do_fork")))) {
+		/* This is special case for emulated single step */
+		v2printk("Emul: rewind hit single step bp\n");
+		restart_from_top_after_write = 1;
+	} else if (strcmp(arg, "silent") && ip + offset != addr) {
 		eprintk("kgdbts: BP mismatch %lx expected %lx\n",
 			   ip + offset, addr);
 		return 1;
 	}
 	/* Readjust the instruction pointer if needed */
 	ip += offset;
+	cont_addr = ip;
 #ifdef GDB_ADJUSTS_BREAK_OFFSET
 	instruction_pointer_set(&kgdbts_regs, ip);
 #endif
@@ -315,6 +339,8 @@ static int check_and_rewind_pc(char *put_str, char *arg)
 static int check_single_step(char *put_str, char *arg)
 {
 	unsigned long addr = lookup_addr(arg);
+	static int matched_id;
+
 	/*
 	 * From an arch indepent point of view the instruction pointer
 	 * should be on a different instruction
@@ -324,6 +350,29 @@ static int check_single_step(char *put_str, char *arg)
 	gdb_regs_to_pt_regs(kgdbts_gdb_regs, &kgdbts_regs);
 	v2printk("Singlestep stopped at IP: %lx\n",
 		   instruction_pointer(&kgdbts_regs));
+
+	if (sstep_thread_id != cont_thread_id) {
+		/*
+		 * Ensure we stopped in the same thread id as before, else the
+		 * debugger should continue until the original thread that was
+		 * single stepped is scheduled again, emulating gdb's behavior.
+		 */
+		v2printk("ThrID does not match: %lx\n", cont_thread_id);
+		if (arch_needs_sstep_emulation) {
+			if (matched_id &&
+			    instruction_pointer(&kgdbts_regs) != addr)
+				goto continue_test;
+			matched_id++;
+			ts.idx -= 2;
+			sstep_state = 0;
+			return 0;
+		}
+		cont_instead_of_sstep = 1;
+		ts.idx -= 4;
+		return 0;
+	}
+continue_test:
+	matched_id = 0;
 	if (instruction_pointer(&kgdbts_regs) == addr) {
 		eprintk("kgdbts: SingleStep failed at %lx\n",
 			   instruction_pointer(&kgdbts_regs));
@@ -365,10 +414,40 @@ static int got_break(char *put_str, char *arg)
 	return 1;
 }
 
+static void get_cont_catch(char *arg)
+{
+	/* Always send detach because the test is completed at this point */
+	fill_get_buf("D");
+}
+
+static int put_cont_catch(char *put_str, char *arg)
+{
+	/* This is at the end of the test and we catch any and all input */
+	v2printk("kgdbts: cleanup task: %lx\n", sstep_thread_id);
+	ts.idx--;
+	return 0;
+}
+
+static int emul_reset(char *put_str, char *arg)
+{
+	if (strncmp(put_str, "$OK", 3))
+		return 1;
+	if (restart_from_top_after_write) {
+		restart_from_top_after_write = 0;
+		ts.idx = -1;
+	}
+	return 0;
+}
+
 static void emul_sstep_get(char *arg)
 {
 	if (!arch_needs_sstep_emulation) {
-		fill_get_buf(arg);
+		if (cont_instead_of_sstep) {
+			cont_instead_of_sstep = 0;
+			fill_get_buf("c");
+		} else {
+			fill_get_buf(arg);
+		}
 		return;
 	}
 	switch (sstep_state) {
@@ -398,9 +477,11 @@ static void emul_sstep_get(char *arg)
 static int emul_sstep_put(char *put_str, char *arg)
 {
 	if (!arch_needs_sstep_emulation) {
-		if (!strncmp(put_str+1, arg, 2))
-			return 0;
-		return 1;
+		char *ptr = &put_str[11];
+		if (put_str[1] != 'T' || put_str[2] != '0')
+			return 1;
+		kgdb_hex2long(&ptr, &sstep_thread_id);
+		return 0;
 	}
 	switch (sstep_state) {
 	case 1:
@@ -411,8 +492,7 @@ static int emul_sstep_put(char *put_str, char *arg)
 		v2printk("Stopped at IP: %lx\n",
 			 instruction_pointer(&kgdbts_regs));
 		/* Want to stop at IP + break instruction size by default */
-		sstep_addr = instruction_pointer(&kgdbts_regs) +
-			BREAK_INSTR_SIZE;
+		sstep_addr = cont_addr + BREAK_INSTR_SIZE;
 		break;
 	case 2:
 		if (strncmp(put_str, "$OK", 3)) {
@@ -424,6 +504,9 @@ static int emul_sstep_put(char *put_str, char *arg)
 		if (strncmp(put_str, "$T0", 3)) {
 			eprintk("kgdbts: failed continue sstep\n");
 			return 1;
+		} else {
+			char *ptr = &put_str[11];
+			kgdb_hex2long(&ptr, &sstep_thread_id);
 		}
 		break;
 	case 4:
@@ -502,10 +585,10 @@ static struct test_struct bad_read_test[] = {
 static struct test_struct singlestep_break_test[] = {
 	{ "?", "S0*" }, /* Clear break points */
 	{ "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
-	{ "c", "T0*", }, /* Continue */
+	{ "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
+	{ "kgdbts_break_test", "OK", sw_rem_break }, /*remove breakpoint */
 	{ "g", "kgdbts_break_test", NULL, check_and_rewind_pc },
 	{ "write", "OK", write_regs }, /* Write registers */
-	{ "kgdbts_break_test", "OK", sw_rem_break }, /*remove breakpoint */
 	{ "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
 	{ "g", "kgdbts_break_test", NULL, check_single_step },
 	{ "kgdbts_break_test", "OK", sw_break, }, /* set sw breakpoint */
@@ -523,16 +606,16 @@ static struct test_struct singlestep_break_test[] = {
 static struct test_struct do_fork_test[] = {
 	{ "?", "S0*" }, /* Clear break points */
 	{ "do_fork", "OK", sw_break, }, /* set sw breakpoint */
-	{ "c", "T0*", }, /* Continue */
-	{ "g", "do_fork", NULL, check_and_rewind_pc }, /* check location */
-	{ "write", "OK", write_regs }, /* Write registers */
+	{ "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
 	{ "do_fork", "OK", sw_rem_break }, /*remove breakpoint */
+	{ "g", "do_fork", NULL, check_and_rewind_pc }, /* check location */
+	{ "write", "OK", write_regs, emul_reset }, /* Write registers */
 	{ "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
 	{ "g", "do_fork", NULL, check_single_step },
 	{ "do_fork", "OK", sw_break, }, /* set sw breakpoint */
 	{ "7", "T0*", skip_back_repeat_test }, /* Loop based on repeat_test */
 	{ "D", "OK", NULL, final_ack_set }, /* detach and unregister I/O */
-	{ "", "" },
+	{ "", "", get_cont_catch, put_cont_catch },
 };
 
 /* Test for hitting a breakpoint at sys_open for what ever the number
@@ -541,16 +624,16 @@ static struct test_struct do_fork_test[] = {
 static struct test_struct sys_open_test[] = {
 	{ "?", "S0*" }, /* Clear break points */
 	{ "sys_open", "OK", sw_break, }, /* set sw breakpoint */
-	{ "c", "T0*", }, /* Continue */
-	{ "g", "sys_open", NULL, check_and_rewind_pc }, /* check location */
-	{ "write", "OK", write_regs }, /* Write registers */
+	{ "c", "T0*", NULL, get_thread_id_continue }, /* Continue */
 	{ "sys_open", "OK", sw_rem_break }, /*remove breakpoint */
+	{ "g", "sys_open", NULL, check_and_rewind_pc }, /* check location */
+	{ "write", "OK", write_regs, emul_reset }, /* Write registers */
 	{ "s", "T0*", emul_sstep_get, emul_sstep_put }, /* Single step */
 	{ "g", "sys_open", NULL, check_single_step },
 	{ "sys_open", "OK", sw_break, }, /* set sw breakpoint */
 	{ "7", "T0*", skip_back_repeat_test }, /* Loop based on repeat_test */
 	{ "D", "OK", NULL, final_ack_set }, /* detach and unregister I/O */
-	{ "", "" },
+	{ "", "", get_cont_catch, put_cont_catch },
 };
 
 /*
@@ -693,8 +776,8 @@ static int run_simple_test(int is_get_char, int chr)
 	/* This callback is a put char which is when kgdb sends data to
 	 * this I/O module.
 	 */
-	if (ts.tst[ts.idx].get[0] == '\0' &&
-		ts.tst[ts.idx].put[0] == '\0') {
+	if (ts.tst[ts.idx].get[0] == '\0' && ts.tst[ts.idx].put[0] == '\0' &&
+	    !ts.tst[ts.idx].get_handler) {
 		eprintk("kgdbts: ERROR: beyond end of test on"
 			   " '%s' line %i\n", ts.name, ts.idx);
 		return 0;
@@ -907,6 +990,17 @@ static void kgdbts_run_tests(void)
 	if (ptr)
 		sstep_test = simple_strtol(ptr+1, NULL, 10);
 
+	/* All HW break point tests */
+	if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT) {
+		hwbreaks_ok = 1;
+		v1printk("kgdbts:RUN hw breakpoint test\n");
+		run_breakpoint_test(1);
+		v1printk("kgdbts:RUN hw write breakpoint test\n");
+		run_hw_break_test(1);
+		v1printk("kgdbts:RUN access write breakpoint test\n");
+		run_hw_break_test(0);
+	}
+
 	/* required internal KGDB tests */
 	v1printk("kgdbts:RUN plant and detach test\n");
 	run_plant_and_detach_test(0);
@@ -924,35 +1018,11 @@ static void kgdbts_run_tests(void)
 
 	/* ===Optional tests=== */
 
-	/* All HW break point tests */
-	if (arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT) {
-		hwbreaks_ok = 1;
-		v1printk("kgdbts:RUN hw breakpoint test\n");
-		run_breakpoint_test(1);
-		v1printk("kgdbts:RUN hw write breakpoint test\n");
-		run_hw_break_test(1);
-		v1printk("kgdbts:RUN access write breakpoint test\n");
-		run_hw_break_test(0);
-	}
-
 	if (nmi_sleep) {
 		v1printk("kgdbts:RUN NMI sleep %i seconds test\n", nmi_sleep);
 		run_nmi_sleep_test(nmi_sleep);
 	}
 
-#ifdef CONFIG_DEBUG_RODATA
-	/* Until there is an api to write to read-only text segments, use
-	 * HW breakpoints for the remainder of any tests, else print a
-	 * failure message if hw breakpoints do not work.
-	 */
-	if (!(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT && hwbreaks_ok)) {
-		eprintk("kgdbts: HW breakpoints do not work,"
-			"skipping remaining tests\n");
-		return;
-	}
-	force_hwbrks = 1;
-#endif /* CONFIG_DEBUG_RODATA */
-
 	/* If the do_fork test is run it will be the last test that is
 	 * executed because a kernel thread will be spawned at the very
 	 * end to unregister the debug hooks.