diff mbox series

[1/2] arm64: introduce separated bits for mm_context_t flags

Message ID 20170805144022.17260-2-ynorov@caviumnetworks.com
State Superseded
Headers show
Series arm64: cleanup {COMPAT_,}SET_PERSONALITY | expand

Commit Message

Yury Norov Aug. 5, 2017, 2:40 p.m. UTC
Currently mm->context.flags field uses thread_info flags which is not the best
idea for many reasons. For example, mm_context_t doesn't need most of thread_info
flags. And it would be difficult to add new mm-related flag if needed because it
may easily interfere with TIF ones.

To deal with it, the new MMCF_AARCH32 flag is introduced for mm_context_t flags,
where MMCF prefix stands for mm_context_t flags.

RFC: https://lkml.org/lkml/2017/7/31/454
v1:
 - changed the MMCF_AARCH32 bit number from 0x1 to 0x0 and added comment.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>

CC: Pratyush Anand <panand@redhat.com>
CC: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/elf.h       | 4 ++--
 arch/arm64/include/asm/mmu.h       | 2 ++
 arch/arm64/kernel/probes/uprobes.c | 2 +-
 3 files changed, 5 insertions(+), 3 deletions(-)

-- 
2.11.0

Comments

Catalin Marinas Aug. 8, 2017, 1:51 p.m. UTC | #1
On Sat, Aug 05, 2017 at 05:40:21PM +0300, Yury Norov wrote:
> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h

> index 5468c834b072..2c57b06b2883 100644

> --- a/arch/arm64/include/asm/mmu.h

> +++ b/arch/arm64/include/asm/mmu.h

> @@ -16,6 +16,8 @@

>  #ifndef __ASM_MMU_H

>  #define __ASM_MMU_H

>  

> +#define MMCF_AARCH32	0x0	/* MM hosts AArch32 executables */


Nitpick: drop 0x since it's a bit number not a flag value. We could,
however, make it a value and just stop using (set|clear)_bit functions.
There is no atomicity issue here.

-- 
Catalin
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index acae781f7359..de11ed1484e3 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -139,7 +139,7 @@  typedef struct user_fpsimd_state elf_fpregset_t;
 
 #define SET_PERSONALITY(ex)						\
 ({									\
-	clear_bit(TIF_32BIT, &current->mm->context.flags);		\
+	clear_bit(MMCF_AARCH32, &current->mm->context.flags);		\
 	clear_thread_flag(TIF_32BIT);					\
 	current->personality &= ~READ_IMPLIES_EXEC;			\
 })
@@ -195,7 +195,7 @@  typedef compat_elf_greg_t		compat_elf_gregset_t[COMPAT_ELF_NGREG];
  */
 #define COMPAT_SET_PERSONALITY(ex)					\
 ({									\
-	set_bit(TIF_32BIT, &current->mm->context.flags);		\
+	set_bit(MMCF_AARCH32, &current->mm->context.flags);		\
 	set_thread_flag(TIF_32BIT);					\
  })
 #define COMPAT_ARCH_DLINFO
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 5468c834b072..2c57b06b2883 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -16,6 +16,8 @@ 
 #ifndef __ASM_MMU_H
 #define __ASM_MMU_H
 
+#define MMCF_AARCH32	0x0	/* MM hosts AArch32 executables */
+
 typedef struct {
 	atomic64_t	id;
 	void		*vdso;
diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c
index 26c998534dca..f29ef6b297e4 100644
--- a/arch/arm64/kernel/probes/uprobes.c
+++ b/arch/arm64/kernel/probes/uprobes.c
@@ -40,7 +40,7 @@  int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
 	probe_opcode_t insn;
 
 	/* TODO: Currently we do not support AARCH32 instruction probing */
-	if (test_bit(TIF_32BIT, &mm->context.flags))
+	if (test_bit(MMCF_AARCH32, &mm->context.flags))
 		return -ENOTSUPP;
 	else if (!IS_ALIGNED(addr, AARCH64_INSN_SIZE))
 		return -EINVAL;