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Subject[PATCH v4 5/6] powerpc: Add show_user_instructions()
Date
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: 4bfffeec 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>
---
arch/powerpc/include/asm/stacktrace.h | 13 +++++++++
arch/powerpc/kernel/process.c | 40 +++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
create mode 100644 arch/powerpc/include/asm/stacktrace.h

diff --git a/arch/powerpc/include/asm/stacktrace.h b/arch/powerpc/include/asm/stacktrace.h
new file mode 100644
index 000000000000..6149b53b3bc8
--- /dev/null
+++ 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
index e9533b4d2f08..364645ac732c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1299,6 +1299,46 @@ static void show_instructions(struct pt_regs *regs)
pr_cont("\n");
}

+void show_user_instructions(struct pt_regs *regs)
+{
+ int i;
+ const char *prefix = KERN_INFO "%s[%d]: code: ";
+ unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
+ sizeof(int));
+
+ printk(prefix, current->comm, current->pid);
+
+ for (i = 0; i < instructions_to_print; i++) {
+ int instr;
+
+ if (!(i % 8) && (i > 0)) {
+ pr_cont("\n");
+ printk(prefix, current->comm, current->pid);
+ }
+
+#if !defined(CONFIG_BOOKE)
+ /* If executing with the IMMU off, adjust pc rather
+ * than print XXXXXXXX.
+ */
+ if (!(regs->msr & MSR_IR))
+ pc = (unsigned long)phys_to_virt(pc);
+#endif
+
+ 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;
--
2.17.1
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