powerpc: Add show_user_instructions()

mopsfelder · mpe · commit 88b0fe175735 · 2018-08-08T00:32:30.000+10:00
show_user_instructions() is a slightly modified version of show_instructions() that allows userspace instruction dump. This will be useful within show_signal_msg() to dump userspace instructions of the faulty location. Here is a sample of what show_user_instructions() outputs: pandafault[10850]: code: 4bfffee 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe pandafault[10850]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040 The current->comm and current->pid printed can serve as a glue that links the instructions dump to its originator, allowing messages to be interleaved in the logs. Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/include/asm/stacktrace.h b/arch/powerpc/include/asm/stacktrace.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Stack trace functions.
+ *
+ * Copyright 2018, Murilo Opsfelder Araujo, IBM Corporation.
+ */
+
+#ifndef _ASM_POWERPC_STACKTRACE_H
+#define _ASM_POWERPC_STACKTRACE_H
+
+void show_user_instructions(struct pt_regs *regs);
+
+#endif /* _ASM_POWERPC_STACKTRACE_H */
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
@@ -1299,6 +1299,38 @@ static void show_instructions(struct pt_regs *regs)
 	pr_cont("\n");
 }
 
+void show_user_instructions(struct pt_regs *regs)
+{
+	unsigned long pc;
+	int i;
+
+	pc = regs->nip - (instructions_to_print * 3 / 4 * sizeof(int));
+
+	pr_info("%s[%d]: code: ", current->comm, current->pid);
+
+	for (i = 0; i < instructions_to_print; i++) {
+		int instr;
+
+		if (!(i % 8) && (i > 0)) {
+			pr_cont("\n");
+			pr_info("%s[%d]: code: ", current->comm, current->pid);
+		}
+
+		if (probe_kernel_address((unsigned int __user *)pc, instr)) {
+			pr_cont("XXXXXXXX ");
+		} else {
+			if (regs->nip == pc)
+				pr_cont("<%08x> ", instr);
+			else
+				pr_cont("%08x ", instr);
+		}
+
+		pc += sizeof(int);
+	}
+
+	pr_cont("\n");
+}
+
 struct regbit {
 	unsigned long bit;
 	const char *name;
