[PATCH v4 1/3] powerpc/process: fix casting and missing header

[PATCH v4 1/3] powerpc/process: fix casting and missing header

[Christophe Leroy]

This patch fixes the following warnings. The first ones are leftovers
from when __get_user() was replaced by probe_kernel_address().

The last one is from when show_user_instructions() was added.

arch/powerpc/kernel/process.c:1287:22: warning: incorrect type in argument 2 (different address spaces)
arch/powerpc/kernel/process.c:1287:22:    expected void const *src
arch/powerpc/kernel/process.c:1287:22:    got unsigned int [noderef] <asn:1>*<noident>
arch/powerpc/kernel/process.c:1319:21: warning: incorrect type in argument 2 (different address spaces)
arch/powerpc/kernel/process.c:1319:21:    expected void const *src
arch/powerpc/kernel/process.c:1319:21:    got unsigned int [noderef] <asn:1>*<noident>
arch/powerpc/kernel/process.c:1302:6: warning: symbol 'show_user_instructions' was not declared. Should it be static?

Fixes: 7b051f665c32d ("powerpc: Use probe_kernel_address in show_instructions")
Fixes: 88b0fe1757359 ("powerpc: Add show_user_instructions()")
Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 v4: no change. Serie rebased on top of latest powerpc/merge (87dbfc1308ee)
 v3: new in v3 to fix sparse warnings reported by snowpatch on the serie

 arch/powerpc/kernel/process.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index d9d4eb2ea6c9..3396c419abf2 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -65,6 +65,7 @@
 #include <asm/livepatch.h>
 #include <asm/cpu_has_feature.h>
 #include <asm/asm-prototypes.h>
+#include <asm/stacktrace.h>
 
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
@@ -1281,7 +1282,7 @@ static void show_instructions(struct pt_regs *regs)
 #endif
 
 		if (!__kernel_text_address(pc) ||
-		     probe_kernel_address((unsigned int __user *)pc, instr)) {
+		    probe_kernel_address((const void *)pc, instr)) {
 			pr_cont("XXXXXXXX ");
 		} else {
 			if (regs->nip == pc)
@@ -1323,7 +1324,7 @@ void show_user_instructions(struct pt_regs *regs)
 			pr_info("%s[%d]: code: ", current->comm, current->pid);
 		}
 
-		if (probe_kernel_address((unsigned int __user *)pc, instr)) {
+		if (probe_kernel_address((const void *)pc, instr)) {
 			pr_cont("XXXXXXXX ");
 		} else {
 			if (regs->nip == pc)
-- 
2.13.3

[PATCH v4 2/3] powerpc/process: fix interleaved output in show_user_instructions()

[Christophe Leroy]

When two processes crash at the same time, we sometimes encounter
interleaving in the middle of a line:

[    4.365317] init[1]: segfault (11) at 0 nip 0 lr 0 code 1
[    4.370452] init[1]: code: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
[    4.372042] init[74]: segfault (11) at 10a74 nip 1000c198 lr 100078c8 code 1 in sh[10000000+14000]
[    4.386829] XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
[    4.391542] init[1]: code: XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
[    4.400863] init[74]: code: 90010024 bf61000c 91490a7c 3fa01002 3be00000 7d3e4b78 3bbd0c20 3b600000
[    4.409867] init[74]: code: 3b9d0040 7c7fe02e 2f830000 419e0028 <89230000> 2f890000 41be001c 4b7f6e79

This patch fixes it by preparing complete lines in a buffer and
printing it at once.

Fixes: 88b0fe1757359 ("powerpc: Add show_user_instructions()")
Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 v4: rebased
 v3: no change
 v2: Using seq_buf and reworked the loop to avoid redundant prints.

 arch/powerpc/kernel/process.c | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 3396c419abf2..8dabf656d924 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -43,6 +43,7 @@
 #include <linux/uaccess.h>
 #include <linux/elf-randomize.h>
 #include <linux/pkeys.h>
+#include <linux/seq_buf.h>
 
 #include <asm/pgtable.h>
 #include <asm/io.h>
@@ -1300,7 +1301,9 @@ static void show_instructions(struct pt_regs *regs)
 void show_user_instructions(struct pt_regs *regs)
 {
 	unsigned long pc;
-	int i;
+	int n = instructions_to_print;
+	struct seq_buf s;
+	char buf[96]; /* enough for 8 times 9 + 2 chars */
 
 	pc = regs->nip - (instructions_to_print * 3 / 4 * sizeof(int));
 
@@ -1314,29 +1317,27 @@ void show_user_instructions(struct pt_regs *regs)
 		return;
 	}
 
-	pr_info("%s[%d]: code: ", current->comm, current->pid);
+	seq_buf_init(&s, buf, sizeof(buf));
 
-	for (i = 0; i < instructions_to_print; i++) {
-		int instr;
+	while (n) {
+		int i;
 
-		if (!(i % 8) && (i > 0)) {
-			pr_cont("\n");
-			pr_info("%s[%d]: code: ", current->comm, current->pid);
-		}
+		seq_buf_clear(&s);
 
-		if (probe_kernel_address((const void *)pc, instr)) {
-			pr_cont("XXXXXXXX ");
-		} else {
-			if (regs->nip == pc)
-				pr_cont("<%08x> ", instr);
-			else
-				pr_cont("%08x ", instr);
+		for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) {
+			int instr;
+
+			if (probe_kernel_address((const void *)pc, instr)) {
+				seq_buf_puts(&s, "XXXXXXXX ");
+				continue;
+			}
+			seq_buf_printf(&s, regs->nip == pc ? "<%08x> " : "%08x ", instr);
 		}
 
-		pc += sizeof(int);
+		if (!seq_buf_has_overflowed(&s))
+			pr_info("%s[%d]: code: %s\n", current->comm,
+				current->pid, s.buffer);
 	}
-
-	pr_cont("\n");
 }
 
 struct regbit {
-- 
2.13.3

[PATCH v4 3/3] powerpc/process: Constify the number of insns printed by show instructions functions.

[Christophe Leroy]

instructions_to_print var is assigned value 16 and there is no
way to change it.

This patch replaces it by a constant.

Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 v4: rebased
 v3: no change
 v2: no change

 arch/powerpc/kernel/process.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 8dabf656d924..dd8447d3f0bf 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1258,17 +1258,16 @@ struct task_struct *__switch_to(struct task_struct *prev,
 	return last;
 }
 
-static int instructions_to_print = 16;
+#define NR_INSN_TO_PRINT	16
 
 static void show_instructions(struct pt_regs *regs)
 {
 	int i;
-	unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
-			sizeof(int));
+	unsigned long pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));
 
 	printk("Instruction dump:");
 
-	for (i = 0; i < instructions_to_print; i++) {
+	for (i = 0; i < NR_INSN_TO_PRINT; i++) {
 		int instr;
 
 		if (!(i % 8))
@@ -1301,17 +1300,17 @@ static void show_instructions(struct pt_regs *regs)
 void show_user_instructions(struct pt_regs *regs)
 {
 	unsigned long pc;
-	int n = instructions_to_print;
+	int n = NR_INSN_TO_PRINT;
 	struct seq_buf s;
 	char buf[96]; /* enough for 8 times 9 + 2 chars */
 
-	pc = regs->nip - (instructions_to_print * 3 / 4 * sizeof(int));
+	pc = regs->nip - (NR_INSN_TO_PRINT * 3 / 4 * sizeof(int));
 
 	/*
 	 * Make sure the NIP points at userspace, not kernel text/data or
 	 * elsewhere.
 	 */
-	if (!__access_ok(pc, instructions_to_print * sizeof(int), USER_DS)) {
+	if (!__access_ok(pc, NR_INSN_TO_PRINT * sizeof(int), USER_DS)) {
 		pr_info("%s[%d]: Bad NIP, not dumping instructions.\n",
 			current->comm, current->pid);
 		return;
-- 
2.13.3

Re: [v4,1/3] powerpc/process: fix casting and missing header

[Michael Ellerman]

On Sat, 2018-10-06 at 16:51:12 UTC, Christophe Leroy wrote:
> This patch fixes the following warnings. The first ones are leftovers
> from when __get_user() was replaced by probe_kernel_address().
> 
> The last one is from when show_user_instructions() was added.
> 
> arch/powerpc/kernel/process.c:1287:22: warning: incorrect type in argument 2 (different address spaces)
> arch/powerpc/kernel/process.c:1287:22:    expected void const *src
> arch/powerpc/kernel/process.c:1287:22:    got unsigned int [noderef] <asn:1>*<noident>
> arch/powerpc/kernel/process.c:1319:21: warning: incorrect type in argument 2 (different address spaces)
> arch/powerpc/kernel/process.c:1319:21:    expected void const *src
> arch/powerpc/kernel/process.c:1319:21:    got unsigned int [noderef] <asn:1>*<noident>
> arch/powerpc/kernel/process.c:1302:6: warning: symbol 'show_user_instructions' was not declared. Should it be static?
> 
> Fixes: 7b051f665c32d ("powerpc: Use probe_kernel_address in show_instructions")
> Fixes: 88b0fe1757359 ("powerpc: Add show_user_instructions()")
> Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/3b35bd48b8a06e02a25af84baba782

cheers