[PATCH v3 1/3] powerpc/process: fix casting and missing header

[PATCH v3 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()")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 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 913c5725cdb2..e108e1ef2b85 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>
@@ -1284,7 +1285,7 @@ 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)
@@ -1316,7 +1317,7 @@ 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 v3 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()")
Cc: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 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 e108e1ef2b85..2a39f7aca846 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>
@@ -1303,33 +1304,33 @@ 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));
 
-	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 v3 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.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 v3: no change
 v2: no change

 arch/powerpc/kernel/process.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 2a39f7aca846..7d86b4f7949e 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1261,17 +1261,16 @@ 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))
@@ -1304,11 +1303,11 @@ 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));
 
 	seq_buf_init(&s, buf, sizeof(buf));
 
-- 
2.13.3

Re: [PATCH v3 1/3] powerpc/process: fix casting and missing header

[Murilo Opsfelder Araujo]

On Fri, Sep 07, 2018 at 01:47:29PM +0000, 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()")
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Smoke test passed.  Thank you.

Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>

> ---
>  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 913c5725cdb2..e108e1ef2b85 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>
> @@ -1284,7 +1285,7 @@ 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)
> @@ -1316,7 +1317,7 @@ 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
> 

-- 
Murilo

Re: [PATCH v3 2/3] powerpc/process: fix interleaved output in show_user_instructions()

[Murilo Opsfelder Araujo]

On Fri, Sep 07, 2018 at 01:47:31PM +0000, Christophe Leroy wrote:
> 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()")
> Cc: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>

> ---
>  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 e108e1ef2b85..2a39f7aca846 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>
> @@ -1303,33 +1304,33 @@ 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));
>  
> -	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
> 

-- 
Murilo

Re: [PATCH v3 3/3] powerpc/process: Constify the number of insns printed by show instructions functions.

[Murilo Opsfelder Araujo]

On Fri, Sep 07, 2018 at 01:47:33PM +0000, Christophe Leroy wrote:
> instructions_to_print var is assigned value 16 and there is no
> way to change it.
> 
> This patch replaces it by a constant.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>

> ---
>  v3: no change
>  v2: no change
> 
>  arch/powerpc/kernel/process.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index 2a39f7aca846..7d86b4f7949e 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -1261,17 +1261,16 @@ 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))
> @@ -1304,11 +1303,11 @@ 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));
>  
>  	seq_buf_init(&s, buf, sizeof(buf));
>  
> -- 
> 2.13.3
> 

-- 
Murilo