i386: convert mm_context_t semaphore to a mutex

PATCH In review Luiz Fernando N. Capitulino 3 participants 12 messages Aug 3, 2007 – Aug 6, 2007 ptrace support

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Luiz Fernando N. Capitulino

author

2007-08-03 13:56 UTC #0 lore raw

PATCH 1/1 i386: convert mm_context_t semaphore to a mutex

Signed-off-by Luiz Fernando N. Capitulino <[email protected]>

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 4 files changed, 12 insertions(+), 11 deletions(-)

arch/i386/kernel/ldt.c +7 -7

@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }

@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;

@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {

@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)

@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }

arch/i386/kernel/ptrace.c +2 -2

@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {

@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }

include/asm-i386/mmu.h +2 -2

@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.

@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;

arch/i386/kernel/i386_ksyms.c +1 -0

@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>

Signature · 1 line

Luiz Fernando N. Capitulino

Ingo Molnar

2007-08-06 07:46 UTC #1 lore raw

include/asm-i386/mmu.h line 13

Quoted 5 lines

typedef struct {
include/asm-i386/mmu.h +1 -1
 	int size;
-	struct semaphore sem;
+	struct mutex lock;

hm, looks good to me but i'm wondering why this was a holdout for such a long time :-) Did you manage to test actual LDT functionality with this patch applied?

Ingo

Luiz Fernando N. Capitulino

author

2007-08-06 13:48 UTC #2 lore raw

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <[email protected]> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

No, I didn't. The only test I did was to run the kernel with this
patch applied.

I'll manage to test it then. Do you have a test-case or has any
suggestion?

Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

arch/i386/kernel/ldt.c +7 -7

@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }

@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;

@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {

@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)

@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }

arch/i386/kernel/ptrace.c +2 -2

@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {

@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }

include/asm-i386/mmu.h +2 -2

@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.

@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;

arch/i386/kernel/i386_ksyms.c +1 -0

@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>

arch/i386/mm/fault.c +2 -2

@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {

@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();

Signature · 1 line

Luiz Fernando N. Capitulino

Luiz Fernando N. Capitulino

author

2007-08-06 13:49 UTC #3 lore raw

In reply to Ingo Molnar

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <[email protected]> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

No, I didn't. The only test I did was to run the kernel with this
patch applied.

I'll manage to test it then. Do you have a test-case or has any
suggestion?

Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

arch/i386/kernel/ldt.c +7 -7

@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }

@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;

@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {

@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)

@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }

arch/i386/kernel/ptrace.c +2 -2

@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {

@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }

include/asm-i386/mmu.h +2 -2

@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.

@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;

arch/i386/kernel/i386_ksyms.c +1 -0

@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>

arch/i386/mm/fault.c +2 -2

@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {

@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();

Signature · 1 line

Luiz Fernando N. Capitulino

Luiz Fernando N. Capitulino

author

2007-08-06 13:49 UTC #9 lore raw

In reply to Ingo Molnar

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <[email protected]> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

No, I didn't. The only test I did was to run the kernel with this
patch applied.

I'll manage to test it then. Do you have a test-case or has any
suggestion?

Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

arch/i386/kernel/ldt.c +7 -7

@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }

@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;

@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {

@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)

@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }

arch/i386/kernel/ptrace.c +2 -2

@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {

@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }

include/asm-i386/mmu.h +2 -2

@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.

@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;

arch/i386/kernel/i386_ksyms.c +1 -0

@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>

arch/i386/mm/fault.c +2 -2

@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {

@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();

Signature · 1 line

Luiz Fernando N. Capitulino

Luiz Fernando N. Capitulino

author

2007-08-06 13:50 UTC #11 lore raw

In reply to Ingo Molnar

Em Mon, 6 Aug 2007 09:46:08 +0200
Ingo Molnar <[email protected]> escreveu:

| 
| >  typedef struct { 
| >  	int size;
| > -	struct semaphore sem;
| > +	struct mutex lock;
| 
| hm, looks good to me but i'm wondering why this was a holdout for such a 
| long time :-) Did you manage to test actual LDT functionality with this 
| patch applied?

No, I didn't. The only test I did was to run the kernel with this
patch applied.

I'll manage to test it then. Do you have a test-case or has any
suggestion?

Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' so the
patch I sent was incomplete. Fixed version below. Shame on me.

[PATCH] i386: convert mm_context_t semaphore to a mutex

---
 arch/i386/kernel/i386_ksyms.c |    1 +
 arch/i386/kernel/ldt.c        |   14 +++++++-------
 arch/i386/kernel/ptrace.c     |    4 ++--
 arch/i386/mm/fault.c          |    4 ++--
 include/asm-i386/mmu.h        |    4 ++--
 5 files changed, 14 insertions(+), 13 deletions(-)

arch/i386/kernel/ldt.c +7 -7

@@ -94,13 +94,13 @@ int init_new_context(struct task_struct 
 	struct mm_struct * old_mm;
 	int retval = 0;
 
-	init_MUTEX(&mm->context.sem);
+	mutex_init(&mm->context.lock);
 	mm->context.size = 0;
 	old_mm = current->mm;
 	if (old_mm && old_mm->context.size > 0) {
-		down(&old_mm->context.sem);
+		mutex_lock(&old_mm->context.lock);
 		retval = copy_ldt(&mm->context, &old_mm->context);
-		up(&old_mm->context.sem);
+		mutex_unlock(&old_mm->context.lock);
 	}
 	return retval;
 }

@@ -132,7 +132,7 @@ static int read_ldt(void __user * ptr, u
 	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
 		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	size = mm->context.size*LDT_ENTRY_SIZE;
 	if (size > bytecount)
 		size = bytecount;

@@ -140,7 +140,7 @@ static int read_ldt(void __user * ptr, u
 	err = 0;
 	if (copy_to_user(ptr, mm->context.ldt, size))
 		err = -EFAULT;
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 	if (err < 0)
 		goto error_return;
 	if (size != bytecount) {

@@ -196,7 +196,7 @@ static int write_ldt(void __user * ptr, 
 			goto out;
 	}
 
-	down(&mm->context.sem);
+	mutex_lock(&mm->context.lock);
 	if (ldt_info.entry_number >= mm->context.size) {
 		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
 		if (error < 0)

@@ -223,7 +223,7 @@ install:
 	error = 0;
 
 out_unlock:
-	up(&mm->context.sem);
+	mutex_unlock(&mm->context.lock);
 out:
 	return error;
 }

arch/i386/kernel/ptrace.c +2 -2

@@ -166,7 +166,7 @@ static unsigned long convert_eip_to_line
 
 		seg &= ~7UL;
 
-		down(&child->mm->context.sem);
+		mutex_lock(&child->mm->context.lock);
 		if (unlikely((seg >> 3) >= child->mm->context.size))
 			addr = -1L; /* bogus selector, access would fault */
 		else {

@@ -180,7 +180,7 @@ static unsigned long convert_eip_to_line
 				addr &= 0xffff;
 			addr += base;
 		}
-		up(&child->mm->context.sem);
+		mutex_unlock(&child->mm->context.lock);
 	}
 	return addr;
 }

include/asm-i386/mmu.h +2 -2

@@ -1,7 +1,7 @@
 #ifndef __i386_MMU_H
 #define __i386_MMU_H
 
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
 /*
  * The i386 doesn't have a mmu context, but
  * we put the segment information here.

@@ -10,7 +10,7 @@
  */
 typedef struct { 
 	int size;
-	struct semaphore sem;
+	struct mutex lock;
 	void *ldt;
 	void *vdso;
 } mm_context_t;

arch/i386/kernel/i386_ksyms.c +1 -0

@@ -1,4 +1,5 @@
 #include <linux/module.h>
+#include <asm/semaphore.h>
 #include <asm/checksum.h>
 #include <asm/desc.h>

arch/i386/mm/fault.c +2 -2

@@ -110,7 +110,7 @@ static inline unsigned long get_segment_
 	   LDT and other horrors are only used in user space. */
 	if (seg & (1<<2)) {
 		/* Must lock the LDT while reading it. */
-		down(&current->mm->context.sem);
+		mutex_lock(&current->mm->context.lock);
 		desc = current->mm->context.ldt;
 		desc = (void *)desc + (seg & ~7);
 	} else {

@@ -123,7 +123,7 @@ static inline unsigned long get_segment_
 	base = get_desc_base((unsigned long *)desc);
 
 	if (seg & (1<<2)) { 
-		up(&current->mm->context.sem);
+		mutex_unlock(&current->mm->context.lock);
 	} else
 		put_cpu();

Signature · 1 line

Luiz Fernando N. Capitulino

Ingo Molnar

2007-08-06 15:25 UTC #4 lore raw

In reply to Luiz Fernando N. Capitulino

Quoted 9 lines · Luiz Fernando N. Capitulino

| hm, looks good to me but i'm wondering why this was a holdout for 
| such a long time :-) Did you manage to test actual LDT functionality 
| with this patch applied?
No, I didn't. The only test I did was to run the kernel with this
patch applied.
I'll manage to test it then. Do you have a test-case or has any
suggestion?

i think try any pthread program with:

export LD_ASSUME_KERNEL=2.4.0

should trigger the LDT code. Try stracing the code and modify_ldt calls should show up.

Quoted 1 line

Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' [...]

heh. After a dozen of such incidents i scripted my editor command to automatically do the quilt add :)

Ingo

Luiz Fernando N. Capitulino

author

2007-08-06 17:15 UTC #5 lore raw

Em Mon, 6 Aug 2007 17:25:02 +0200
Ingo Molnar <[email protected]> escreveu:

| 
| * Luiz Fernando N. Capitulino <[email protected]> wrote:
| 
| > | hm, looks good to me but i'm wondering why this was a holdout for 
| > | such a long time :-) Did you manage to test actual LDT functionality 
| > | with this patch applied?
| > 
| >  No, I didn't. The only test I did was to run the kernel with this 
| > patch applied.
| > 
| >  I'll manage to test it then. Do you have a test-case or has any 
| > suggestion?
| 
| i think try any pthread program with:
| 
|    export LD_ASSUME_KERNEL=2.4.0
| 
| should trigger the LDT code. Try stracing the code and modify_ldt calls 
| should show up.

I couldn't run this because my libc requires 2.6 kernels.

But I've managed to run wine with a game called 'Align-it!', and
I have the following result:

"""
~/tmp/ egrep -c 'modify_ldt' wine-strace.txt
46
~/tmp/
"""

I've checked the calls and none has failed. Not sure how good
this test is though.

Maybe it could be more tested in -mm?

| >  Oh, btw, I forgot to 'quilt add arch/i386/mm/fault.c' [...]
| 
| heh. After a dozen of such incidents i scripted my editor command to 
| automatically do the quilt add :)

Oh, that's a good tip.

Thanks a lot,

Signature · 1 line

Luiz Fernando N. Capitulino

Ingo Molnar

Acked-by

2007-08-06 17:43 UTC #6 lore raw

Quoted 11 lines · Luiz Fernando N. Capitulino

But I've managed to run wine with a game called 'Align-it!', and
I have the following result:
"""
~/tmp/ egrep -c 'modify_ldt' wine-strace.txt
46
~/tmp/
"""
I've checked the calls and none has failed. Not sure how good
this test is though.

ok, this is certainly good enough.

Acked-by Ingo Molnar <[email protected]>

Ingo

Andi Kleen

2007-08-06 18:38 UTC #7 lore raw

In reply to Luiz Fernando N. Capitulino

Quoted 3 lines · Luiz Fernando N. Capitulino

I'll manage to test it then. Do you have a test-case or has any
suggestion?

LTP has some simple test cases for modify_ldt

-Andi

Luiz Fernando N. Capitulino

author

2007-08-06 20:37 UTC #8 lore raw

Em 06 Aug 2007 21:32:29 +0200
Andi Kleen <[email protected]> escreveu:

| "Luiz Fernando N. Capitulino" <[email protected]> writes:
| > 
| >  I'll manage to test it then. Do you have a test-case or has any
| > suggestion?
| 
| LTP has some simple test cases for modify_ldt

I've just ran them from a LTP suite from 2007/04/30:

"""
/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ ./modify_ldt01

modify_ldt01    0  INFO  :  Enter block 1
modify_ldt01    0  INFO  :  block 1 PASSED
modify_ldt01    0  INFO  :  Exit block 1
modify_ldt01    0  INFO  :  Enter block 2
modify_ldt01    0  INFO  :  block 2 PASSED
modify_ldt01    0  INFO  :  Exit block 2
modify_ldt01    0  INFO  :  block 3 PASSED
modify_ldt01    0  INFO  :  Exit block 3

"""

"""
/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ ./modify_ldt02

modify_ldt02    0  INFO  :  Enter block 1
modify_ldt02    0  INFO  :  block 1 PASSED
modify_ldt02    0  INFO  :  Exit block 1
modify_ldt02    0  INFO  :  Enter block 2
modify_ldt02    0  INFO  :  received signal: 11
modify_ldt02    0  INFO  :  block 2 PASSED

/usr/lib/ltp/testcases/kernel/syscalls/modify_ldt/ """

All passed it seems.

Btw, I've send the same patch for x86_64 to you too.

Signature · 1 line

Luiz Fernando N. Capitulino

Luiz Fernando N. Capitulino

author

2007-08-06 21:10 UTC #10 lore raw

In reply to Luiz Fernando N. Capitulino

Em Mon, 6 Aug 2007 10:36:55 -0300
"Luiz Fernando N. Capitulino" <[email protected]> escreveu:

| Em Mon, 6 Aug 2007 09:46:08 +0200
| Ingo Molnar <[email protected]> escreveu:
| 
| | 
| | >  typedef struct { 
| | >  	int size;
| | > -	struct semaphore sem;
| | > +	struct mutex lock;
| | 
| | hm, looks good to me but i'm wondering why this was a holdout for such a 
| | long time :-) Did you manage to test actual LDT functionality with this 
| | patch applied?
| 
|  No, I didn't. The only test I did was to run the kernel with this
| patch applied.
| 
|  I'll manage to test it then. Do you have a test-case or has any
| suggestion?

And again, SMTP problems makes me looks like a joker...

Sorry for the spam, just realized the problem now.

Signature · 1 line

Luiz Fernando N. Capitulino