1 files changed, 142 insertions, 76 deletions

diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c
index 1785cd82253c..3aae7f70e6ab 100644
--- a/arch/s390/kernel/stacktrace.c
+++ b/arch/s390/kernel/stacktrace.c
@@ -1,96 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Stack trace management functions
  *
  *  Copyright IBM Corp. 2006
- *  Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
  */
 
-#include <linux/sched.h>
+#include <linux/perf_event.h>
 #include <linux/stacktrace.h>
-#include <linux/kallsyms.h>
-#include <linux/module.h>
-
-static unsigned long save_context_stack(struct stack_trace *trace,
-					unsigned long sp,
-					unsigned long low,
-					unsigned long high,
-					int savesched)
+#include <linux/uaccess.h>
+#include <asm/asm-offsets.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+#include <asm/kprobes.h>
+#include <asm/ptrace.h>
+
+void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+		     struct task_struct *task, struct pt_regs *regs)
 {
-	struct stack_frame *sf;
-	struct pt_regs *regs;
+	struct unwind_state state;
 	unsigned long addr;
 
-	while(1) {
-		sp &= PSW_ADDR_INSN;
-		if (sp < low || sp > high)
-			return sp;
-		sf = (struct stack_frame *)sp;
-		while(1) {
-			addr = sf->gprs[8] & PSW_ADDR_INSN;
-			if (!trace->skip)
-				trace->entries[trace->nr_entries++] = addr;
-			else
-				trace->skip--;
-			if (trace->nr_entries >= trace->max_entries)
-				return sp;
-			low = sp;
-			sp = sf->back_chain & PSW_ADDR_INSN;
-			if (!sp)
-				break;
-			if (sp <= low || sp > high - sizeof(*sf))
-				return sp;
-			sf = (struct stack_frame *)sp;
-		}
-		/* Zero backchain detected, check for interrupt frame. */
-		sp = (unsigned long)(sf + 1);
-		if (sp <= low || sp > high - sizeof(*regs))
-			return sp;
-		regs = (struct pt_regs *)sp;
-		addr = regs->psw.addr & PSW_ADDR_INSN;
-		if (savesched || !in_sched_functions(addr)) {
-			if (!trace->skip)
-				trace->entries[trace->nr_entries++] = addr;
-			else
-				trace->skip--;
-		}
-		if (trace->nr_entries >= trace->max_entries)
-			return sp;
-		low = sp;
-		sp = regs->gprs[15];
+	unwind_for_each_frame(&state, task, regs, 0) {
+		addr = unwind_get_return_address(&state);
+		if (!addr || !consume_entry(cookie, addr))
+			break;
+	}
+}
+
+int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
+			     void *cookie, struct task_struct *task)
+{
+	struct unwind_state state;
+	unsigned long addr;
+
+	unwind_for_each_frame(&state, task, NULL, 0) {
+		if (state.stack_info.type != STACK_TYPE_TASK)
+			return -EINVAL;
+
+		if (state.regs)
+			return -EINVAL;
+
+		addr = unwind_get_return_address(&state);
+		if (!addr)
+			return -EINVAL;
+
+#ifdef CONFIG_RETHOOK
+		/*
+		 * Mark stacktraces with krethook functions on them
+		 * as unreliable.
+		 */
+		if (state.ip == (unsigned long)arch_rethook_trampoline)
+			return -EINVAL;
+#endif
+
+		if (!consume_entry(cookie, addr))
+			return -EINVAL;
+	}
+
+	/* Check for stack corruption */
+	if (unwind_error(&state))
+		return -EINVAL;
+	return 0;
+}
+
+static inline bool store_ip(stack_trace_consume_fn consume_entry, void *cookie,
+			    struct perf_callchain_entry_ctx *entry, bool perf,
+			    unsigned long ip)
+{
+#ifdef CONFIG_PERF_EVENTS
+	if (perf) {
+		if (perf_callchain_store(entry, ip))
+			return false;
+		return true;
 	}
+#endif
+	return consume_entry(cookie, ip);
+}
+
+static inline bool ip_invalid(unsigned long ip)
+{
+	/*
+	 * Perform some basic checks if an instruction address taken
+	 * from unreliable source is invalid.
+	 */
+	if (ip & 1)
+		return true;
+	if (ip < mmap_min_addr)
+		return true;
+	if (ip >= current->mm->context.asce_limit)
+		return true;
+	return false;
 }
 
-void save_stack_trace(struct stack_trace *trace)
+static inline bool ip_within_vdso(unsigned long ip)
 {
-	register unsigned long sp asm ("15");
-	unsigned long orig_sp, new_sp;
-
-	orig_sp = sp & PSW_ADDR_INSN;
-	new_sp = save_context_stack(trace, orig_sp,
-				    S390_lowcore.panic_stack - PAGE_SIZE,
-				    S390_lowcore.panic_stack, 1);
-	if (new_sp != orig_sp)
+	return in_range(ip, current->mm->context.vdso_base, vdso_text_size());
+}
+
+void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
+				 struct perf_callchain_entry_ctx *entry,
+				 const struct pt_regs *regs, bool perf)
+{
+	struct stack_frame_vdso_wrapper __user *sf_vdso;
+	struct stack_frame_user __user *sf;
+	unsigned long ip, sp;
+	bool first = true;
+
+	if (!current->mm)
 		return;
-	new_sp = save_context_stack(trace, new_sp,
-				    S390_lowcore.async_stack - ASYNC_SIZE,
-				    S390_lowcore.async_stack, 1);
-	if (new_sp != orig_sp)
+	ip = instruction_pointer(regs);
+	if (!store_ip(consume_entry, cookie, entry, perf, ip))
 		return;
-	save_context_stack(trace, new_sp,
-			   S390_lowcore.thread_info,
-			   S390_lowcore.thread_info + THREAD_SIZE, 1);
+	sf = (void __user *)user_stack_pointer(regs);
+	pagefault_disable();
+	while (1) {
+		if (__get_user(sp, &sf->back_chain))
+			break;
+		/*
+		 * VDSO entry code has a non-standard stack frame layout.
+		 * See VDSO user wrapper code for details.
+		 */
+		if (!sp && ip_within_vdso(ip)) {
+			sf_vdso = (void __user *)sf;
+			if (__get_user(ip, &sf_vdso->return_address))
+				break;
+			sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD;
+			sf = (void __user *)sp;
+			if (__get_user(sp, &sf->back_chain))
+				break;
+		} else {
+			sf = (void __user *)sp;
+			if (__get_user(ip, &sf->gprs[8]))
+				break;
+		}
+		/* Sanity check: ABI requires SP to be 8 byte aligned. */
+		if (sp & 0x7)
+			break;
+		if (ip_invalid(ip)) {
+			/*
+			 * If the instruction address is invalid, and this
+			 * is the first stack frame, assume r14 has not
+			 * been written to the stack yet. Otherwise exit.
+			 */
+			if (!first)
+				break;
+			ip = regs->gprs[14];
+			if (ip_invalid(ip))
+				break;
+		}
+		if (!store_ip(consume_entry, cookie, entry, perf, ip))
+			break;
+		first = false;
+	}
+	pagefault_enable();
 }
-EXPORT_SYMBOL_GPL(save_stack_trace);
 
-void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
+			  const struct pt_regs *regs)
 {
-	unsigned long sp, low, high;
-
-	sp = tsk->thread.ksp & PSW_ADDR_INSN;
-	low = (unsigned long) task_stack_page(tsk);
-	high = (unsigned long) task_pt_regs(tsk);
-	save_context_stack(trace, sp, low, high, 0);
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
+	arch_stack_walk_user_common(consume_entry, cookie, NULL, regs, false);
 }
-EXPORT_SYMBOL_GPL(save_stack_trace_tsk);