Re: [RFC 2/4] x86/thread_info: kill TIF_ADDR32 in favour of ADDR_LIMIT_32BIT

[Andy Lutomirski]

On Fri, Dec 30, 2016 at 7:56 AM, Dmitry Safonov  wrote:
> This thread flag is completely x86-specific, consolidate it with
> ADDR_LIMIT_32BIT personality which is defined but not used on x86.
> It will free one of thread flags and consolidate personality with
> other arches.
> After this commit ADDR_LIMIT_32BIT is set by the kernel automatically
> in COMPAT_SET_PERSONALITY() for 32-bit ELF files and for 32-bit a.out.
> It's cleared in SET_PERSONALITY() for 64-bit ELFs.

I'm okay with this as a plain cleanup, but I'm not convinced that this
is really the right long-term solution.  See next email.

Re: [RFC 2/4] x86/thread_info: kill TIF_ADDR32 in favour of ADDR_LIMIT_32BIT

[Andy Lutomirski]

On Fri, Dec 30, 2016 at 7:56 AM, Dmitry Safonov  wrote:
> This thread flag is completely x86-specific, consolidate it with
> ADDR_LIMIT_32BIT personality which is defined but not used on x86.
> It will free one of thread flags and consolidate personality with
> other arches.
> After this commit ADDR_LIMIT_32BIT is set by the kernel automatically
> in COMPAT_SET_PERSONALITY() for 32-bit ELF files and for 32-bit a.out.
> It's cleared in SET_PERSONALITY() for 64-bit ELFs.

I'm okay with this as a plain cleanup, but I'm not convinced that this
is really the right long-term solution.  See next email.

[RFC 2/4] x86/thread_info: kill TIF_ADDR32 in favour of ADDR_LIMIT_32BIT

[Dmitry Safonov]

This thread flag is completely x86-specific, consolidate it with
ADDR_LIMIT_32BIT personality which is defined but not used on x86.
It will free one of thread flags and consolidate personality with
other arches.
After this commit ADDR_LIMIT_32BIT is set by the kernel automatically
in COMPAT_SET_PERSONALITY() for 32-bit ELF files and for 32-bit a.out.
It's cleared in SET_PERSONALITY() for 64-bit ELFs.

Signed-off-by: Dmitry Safonov 
---
 arch/x86/include/asm/elf.h | 7 +--
 arch/x86/include/asm/processor.h   | 2 +-
 arch/x86/include/asm/thread_info.h | 4 +---
 arch/x86/kernel/process_64.c   | 4 ++--
 arch/x86/kernel/sys_x86_64.c   | 4 ++--
 5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index e7f155c3045e..02f39b363e61 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -5,6 +5,8 @@
  * ELF register definitions..
  */
 #include 
+#include 
+#include 
 
 #include 
 #include 
@@ -295,7 +297,8 @@ do {
\
 #else /* CONFIG_X86_32 */
 
 /* 1GB for 64bit, 8MB for 32bit */
-#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3f)
+#define STACK_RND_MASK \
+   ((current->personality & ADDR_LIMIT_32BIT) ? 0x7ff : 0x3f)
 
 #define ARCH_DLINFO\
 do {   \
@@ -346,7 +349,7 @@ static inline int mmap_is_ia32(void)
 {
return IS_ENABLED(CONFIG_X86_32) ||
   (IS_ENABLED(CONFIG_COMPAT) &&
-   test_thread_flag(TIF_ADDR32));
+   (current->personality & ADDR_LIMIT_32BIT));
 }
 
 /* Do not change the values. See get_align_mask() */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 090a860b792a..dbc7dec5fa84 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -817,7 +817,7 @@ static inline void spin_lock_prefetch(const void *x)
 #define IA32_PAGE_OFFSET   ((current->personality & ADDR_LIMIT_3GB) ? \
0xc000 : 0xe000)
 
-#define TASK_SIZE  (test_thread_flag(TIF_ADDR32) ? \
+#define TASK_SIZE  (current->personality & ADDR_LIMIT_32BIT ? \
IA32_PAGE_OFFSET : TASK_SIZE_MAX)
 
 #define STACK_TOP  TASK_SIZE
diff --git a/arch/x86/include/asm/thread_info.h 
b/arch/x86/include/asm/thread_info.h
index ad6f5eb07a95..6a5763e6ca1b 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -97,8 +97,7 @@ struct thread_info {
 #define TIF_BLOCKSTEP  25  /* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES   27  /* task is updating the mmu lazily */
 #define TIF_SYSCALL_TRACEPOINT 28  /* syscall tracepoint instrumentation */
-#define TIF_ADDR32 29  /* 32-bit address space on 64 bits */
-#define TIF_X3230  /* 32-bit native x86-64 binary 
*/
+#define TIF_X3229  /* 32-bit native x86-64 binary 
*/
 
 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@@ -119,7 +118,6 @@ struct thread_info {
 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES  (1 << TIF_LAZY_MMU_UPDATES)
 #define _TIF_SYSCALL_TRACEPOINT(1 << TIF_SYSCALL_TRACEPOINT)
-#define _TIF_ADDR32(1 << TIF_ADDR32)
 #define _TIF_X32   (1 << TIF_X32)
 
 /*
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index a61e141b6891..8ce30d40bb33 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -489,8 +489,8 @@ void set_personality_64bit(void)
 
/* Make sure to be in 64bit mode */
clear_thread_flag(TIF_IA32);
-   clear_thread_flag(TIF_ADDR32);
clear_thread_flag(TIF_X32);
+   current->personality &= ~ADDR_LIMIT_32BIT;
 
/* Ensure the corresponding mm is not marked. */
if (current->mm)
@@ -508,7 +508,7 @@ void set_personality_ia32(bool x32)
/* inherit personality from parent */
 
/* Make sure to be in 32bit mode */
-   set_thread_flag(TIF_ADDR32);
+   current->personality |= ADDR_LIMIT_32BIT;
 
/* Mark the associated mm as containing 32-bit tasks. */
if (x32) {
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index a55ed63b9f91..e836a7318f1f 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -100,7 +100,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, 
len,
 static void find_start_end(unsigned long flags, unsigned long *begin,
   unsigned long *end)
 {
-   if 

[RFC 2/4] x86/thread_info: kill TIF_ADDR32 in favour of ADDR_LIMIT_32BIT

[Dmitry Safonov]

This thread flag is completely x86-specific, consolidate it with
ADDR_LIMIT_32BIT personality which is defined but not used on x86.
It will free one of thread flags and consolidate personality with
other arches.
After this commit ADDR_LIMIT_32BIT is set by the kernel automatically
in COMPAT_SET_PERSONALITY() for 32-bit ELF files and for 32-bit a.out.
It's cleared in SET_PERSONALITY() for 64-bit ELFs.

Signed-off-by: Dmitry Safonov 
---
 arch/x86/include/asm/elf.h | 7 +--
 arch/x86/include/asm/processor.h   | 2 +-
 arch/x86/include/asm/thread_info.h | 4 +---
 arch/x86/kernel/process_64.c   | 4 ++--
 arch/x86/kernel/sys_x86_64.c   | 4 ++--
 5 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index e7f155c3045e..02f39b363e61 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -5,6 +5,8 @@
  * ELF register definitions..
  */
 #include 
+#include 
+#include 
 
 #include 
 #include 
@@ -295,7 +297,8 @@ do {
\
 #else /* CONFIG_X86_32 */
 
 /* 1GB for 64bit, 8MB for 32bit */
-#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3f)
+#define STACK_RND_MASK \
+   ((current->personality & ADDR_LIMIT_32BIT) ? 0x7ff : 0x3f)
 
 #define ARCH_DLINFO\
 do {   \
@@ -346,7 +349,7 @@ static inline int mmap_is_ia32(void)
 {
return IS_ENABLED(CONFIG_X86_32) ||
   (IS_ENABLED(CONFIG_COMPAT) &&
-   test_thread_flag(TIF_ADDR32));
+   (current->personality & ADDR_LIMIT_32BIT));
 }
 
 /* Do not change the values. See get_align_mask() */
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 090a860b792a..dbc7dec5fa84 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -817,7 +817,7 @@ static inline void spin_lock_prefetch(const void *x)
 #define IA32_PAGE_OFFSET   ((current->personality & ADDR_LIMIT_3GB) ? \
0xc000 : 0xe000)
 
-#define TASK_SIZE  (test_thread_flag(TIF_ADDR32) ? \
+#define TASK_SIZE  (current->personality & ADDR_LIMIT_32BIT ? \
IA32_PAGE_OFFSET : TASK_SIZE_MAX)
 
 #define STACK_TOP  TASK_SIZE
diff --git a/arch/x86/include/asm/thread_info.h 
b/arch/x86/include/asm/thread_info.h
index ad6f5eb07a95..6a5763e6ca1b 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -97,8 +97,7 @@ struct thread_info {
 #define TIF_BLOCKSTEP  25  /* set when we want DEBUGCTLMSR_BTF */
 #define TIF_LAZY_MMU_UPDATES   27  /* task is updating the mmu lazily */
 #define TIF_SYSCALL_TRACEPOINT 28  /* syscall tracepoint instrumentation */
-#define TIF_ADDR32 29  /* 32-bit address space on 64 bits */
-#define TIF_X3230  /* 32-bit native x86-64 binary 
*/
+#define TIF_X3229  /* 32-bit native x86-64 binary 
*/
 
 #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
@@ -119,7 +118,6 @@ struct thread_info {
 #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP)
 #define _TIF_LAZY_MMU_UPDATES  (1 << TIF_LAZY_MMU_UPDATES)
 #define _TIF_SYSCALL_TRACEPOINT(1 << TIF_SYSCALL_TRACEPOINT)
-#define _TIF_ADDR32(1 << TIF_ADDR32)
 #define _TIF_X32   (1 << TIF_X32)
 
 /*
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index a61e141b6891..8ce30d40bb33 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -489,8 +489,8 @@ void set_personality_64bit(void)
 
/* Make sure to be in 64bit mode */
clear_thread_flag(TIF_IA32);
-   clear_thread_flag(TIF_ADDR32);
clear_thread_flag(TIF_X32);
+   current->personality &= ~ADDR_LIMIT_32BIT;
 
/* Ensure the corresponding mm is not marked. */
if (current->mm)
@@ -508,7 +508,7 @@ void set_personality_ia32(bool x32)
/* inherit personality from parent */
 
/* Make sure to be in 32bit mode */
-   set_thread_flag(TIF_ADDR32);
+   current->personality |= ADDR_LIMIT_32BIT;
 
/* Mark the associated mm as containing 32-bit tasks. */
if (x32) {
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index a55ed63b9f91..e836a7318f1f 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -100,7 +100,7 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, 
len,
 static void find_start_end(unsigned long flags, unsigned long *begin,
   unsigned long *end)
 {
-   if (!test_thread_flag(TIF_ADDR32) && (flags &