1 files changed, 80 insertions, 34 deletions

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 38185aedf7d1..977ee75e047c 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -7,14 +7,23 @@
 #include <asm/unwind.h>
 #include <asm/orc_types.h>
 #include <asm/orc_lookup.h>
+#include <asm/orc_header.h>
+
+ORC_HEADER;
 
 #define orc_warn(fmt, ...) \
 	printk_deferred_once(KERN_WARNING "WARNING: " fmt, ##__VA_ARGS__)
 
 #define orc_warn_current(args...)					\
 ({									\
-	if (state->task == current && !state->error)			\
+	static bool dumped_before;					\
+	if (state->task == current && !state->error) {			\
 		orc_warn(args);						\
+		if (unwind_debug && !dumped_before) {			\
+			dumped_before = true;				\
+			unwind_dump(state);				\
+		}							\
+	}								\
 })
 
 extern int __start_orc_unwind_ip[];
@@ -23,8 +32,49 @@ extern struct orc_entry __start_orc_unwind[];
 extern struct orc_entry __stop_orc_unwind[];
 
 static bool orc_init __ro_after_init;
+static bool unwind_debug __ro_after_init;
 static unsigned int lookup_num_blocks __ro_after_init;
 
+static int __init unwind_debug_cmdline(char *str)
+{
+	unwind_debug = true;
+
+	return 0;
+}
+early_param("unwind_debug", unwind_debug_cmdline);
+
+static void unwind_dump(struct unwind_state *state)
+{
+	static bool dumped_before;
+	unsigned long word, *sp;
+	struct stack_info stack_info = {0};
+	unsigned long visit_mask = 0;
+
+	if (dumped_before)
+		return;
+
+	dumped_before = true;
+
+	printk_deferred("unwind stack type:%d next_sp:%p mask:0x%lx graph_idx:%d\n",
+			state->stack_info.type, state->stack_info.next_sp,
+			state->stack_mask, state->graph_idx);
+
+	for (sp = __builtin_frame_address(0); sp;
+	     sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
+		if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
+			break;
+
+		for (; sp < stack_info.end; sp++) {
+
+			word = READ_ONCE_NOCHECK(*sp);
+
+			printk_deferred("%0*lx: %0*lx (%pB)\n", BITS_PER_LONG/4,
+					(unsigned long)sp, BITS_PER_LONG/4,
+					word, (void *)word);
+		}
+	}
+}
+
 static inline unsigned long orc_ip(const int *ip)
 {
 	return (unsigned long)ip + *ip;
@@ -35,7 +85,7 @@ static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
 {
 	int *first = ip_table;
 	int *last = ip_table + num_entries - 1;
-	int *mid = first, *found = first;
+	int *mid, *found = first;
 
 	if (!num_entries)
 		return NULL;
@@ -93,22 +143,27 @@ static struct orc_entry *orc_find(unsigned long ip);
 static struct orc_entry *orc_ftrace_find(unsigned long ip)
 {
 	struct ftrace_ops *ops;
-	unsigned long caller;
+	unsigned long tramp_addr, offset;
 
 	ops = ftrace_ops_trampoline(ip);
 	if (!ops)
 		return NULL;
 
+	/* Set tramp_addr to the start of the code copied by the trampoline */
 	if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
-		caller = (unsigned long)ftrace_regs_call;
+		tramp_addr = (unsigned long)ftrace_regs_caller;
 	else
-		caller = (unsigned long)ftrace_call;
+		tramp_addr = (unsigned long)ftrace_caller;
+
+	/* Now place tramp_addr to the location within the trampoline ip is at */
+	offset = ip - ops->trampoline;
+	tramp_addr += offset;
 
 	/* Prevent unlikely recursion */
-	if (ip == caller)
+	if (ip == tramp_addr)
 		return NULL;
 
-	return orc_find(caller);
+	return orc_find(tramp_addr);
 }
 #else
 static struct orc_entry *orc_ftrace_find(unsigned long ip)
@@ -128,17 +183,16 @@ static struct orc_entry null_orc_entry = {
 	.sp_offset = sizeof(long),
 	.sp_reg = ORC_REG_SP,
 	.bp_reg = ORC_REG_UNDEFINED,
-	.type = UNWIND_HINT_TYPE_CALL
+	.type = ORC_TYPE_CALL
 };
 
 /* Fake frame pointer entry -- used as a fallback for generated code */
 static struct orc_entry orc_fp_entry = {
-	.type		= UNWIND_HINT_TYPE_CALL,
+	.type		= ORC_TYPE_CALL,
 	.sp_reg		= ORC_REG_BP,
 	.sp_offset	= 16,
 	.bp_reg		= ORC_REG_PREV_SP,
 	.bp_offset	= -16,
-	.end		= 0,
 };
 
 static struct orc_entry *orc_find(unsigned long ip)
@@ -196,7 +250,6 @@ static struct orc_entry *cur_orc_table = __start_orc_unwind;
 static void orc_sort_swap(void *_a, void *_b, int size)
 {
 	struct orc_entry *orc_a, *orc_b;
-	struct orc_entry orc_tmp;
 	int *a = _a, *b = _b, tmp;
 	int delta = _b - _a;
 
@@ -208,9 +261,7 @@ static void orc_sort_swap(void *_a, void *_b, int size)
 	/* Swap the corresponding .orc_unwind entries: */
 	orc_a = cur_orc_table + (a - cur_orc_ip_table);
 	orc_b = cur_orc_table + (b - cur_orc_ip_table);
-	orc_tmp = *orc_a;
-	*orc_a = *orc_b;
-	*orc_b = orc_tmp;
+	swap(*orc_a, *orc_b);
 }
 
 static int orc_sort_cmp(const void *_a, const void *_b)
@@ -226,13 +277,13 @@ static int orc_sort_cmp(const void *_a, const void *_b)
 		return -1;
 
 	/*
-	 * The "weak" section terminator entries need to always be on the left
+	 * The "weak" section terminator entries need to always be first
 	 * to ensure the lookup code skips them in favor of real entries.
 	 * These terminator entries exist to handle any gaps created by
 	 * whitelisted .o files which didn't get objtool generation.
 	 */
 	orc_a = cur_orc_table + (a - cur_orc_ip_table);
-	return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
+	return orc_a->type == ORC_TYPE_UNDEFINED ? -1 : 1;
 }
 
 void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
@@ -425,7 +476,7 @@ bool unwind_next_frame(struct unwind_state *state)
 		return false;
 
 	/* Don't let modules unload while we're reading their ORC data. */
-	preempt_disable();
+	guard(rcu)();
 
 	/* End-of-stack check for user tasks: */
 	if (state->regs && user_mode(state->regs))
@@ -450,16 +501,16 @@ bool unwind_next_frame(struct unwind_state *state)
 		 */
 		orc = &orc_fp_entry;
 		state->error = true;
-	}
-
-	/* End-of-stack check for kernel threads: */
-	if (orc->sp_reg == ORC_REG_UNDEFINED) {
-		if (!orc->end)
+	} else {
+		if (orc->type == ORC_TYPE_UNDEFINED)
 			goto err;
 
-		goto the_end;
+		if (orc->type == ORC_TYPE_END_OF_STACK)
+			goto the_end;
 	}
 
+	state->signal = orc->signal;
+
 	/* Find the previous frame's stack: */
 	switch (orc->sp_reg) {
 	case ORC_REG_SP:
@@ -528,7 +579,7 @@ bool unwind_next_frame(struct unwind_state *state)
 
 	/* Find IP, SP and possibly regs: */
 	switch (orc->type) {
-	case UNWIND_HINT_TYPE_CALL:
+	case ORC_TYPE_CALL:
 		ip_p = sp - sizeof(long);
 
 		if (!deref_stack_reg(state, ip_p, &state->ip))
@@ -539,10 +590,9 @@ bool unwind_next_frame(struct unwind_state *state)
 		state->sp = sp;
 		state->regs = NULL;
 		state->prev_regs = NULL;
-		state->signal = false;
 		break;
 
-	case UNWIND_HINT_TYPE_REGS:
+	case ORC_TYPE_REGS:
 		if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
 			orc_warn_current("can't access registers at %pB\n",
 					 (void *)orig_ip);
@@ -563,16 +613,15 @@ bool unwind_next_frame(struct unwind_state *state)
 		state->regs = (struct pt_regs *)sp;
 		state->prev_regs = NULL;
 		state->full_regs = true;
-		state->signal = true;
 		break;
 
-	case UNWIND_HINT_TYPE_REGS_PARTIAL:
+	case ORC_TYPE_REGS_PARTIAL:
 		if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
 			orc_warn_current("can't access iret registers at %pB\n",
 					 (void *)orig_ip);
 			goto err;
 		}
-		/* See UNWIND_HINT_TYPE_REGS case comment. */
+		/* See ORC_TYPE_REGS case comment. */
 		state->ip = unwind_recover_rethook(state, state->ip,
 				(unsigned long *)(state->sp - sizeof(long)));
 
@@ -580,7 +629,6 @@ bool unwind_next_frame(struct unwind_state *state)
 			state->prev_regs = state->regs;
 		state->regs = (void *)sp - IRET_FRAME_OFFSET;
 		state->full_regs = false;
-		state->signal = true;
 		break;
 
 	default:
@@ -621,14 +669,12 @@ bool unwind_next_frame(struct unwind_state *state)
 		goto err;
 	}
 
-	preempt_enable();
 	return true;
 
 err:
 	state->error = true;
 
 the_end:
-	preempt_enable();
 	state->stack_info.type = STACK_TYPE_UNKNOWN;
 	return false;
 }
@@ -675,7 +721,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		state->sp = task->thread.sp + sizeof(*frame);
 		state->bp = READ_ONCE_NOCHECK(frame->bp);
 		state->ip = READ_ONCE_NOCHECK(frame->ret_addr);
-		state->signal = (void *)state->ip == ret_from_fork;
+		state->signal = (void *)state->ip == ret_from_fork_asm;
 	}
 
 	if (get_stack_info((unsigned long *)state->sp, state->task,
@@ -708,7 +754,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 	/* Otherwise, skip ahead to the user-specified starting frame: */
 	while (!unwind_done(state) &&
 	       (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
-			state->sp < (unsigned long)first_frame))
+			state->sp <= (unsigned long)first_frame))
 		unwind_next_frame(state);
 
 	return;