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arm64: introduce separated bits for mm_context_t flags 

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.
Also, mm_context_t flag doesn't require atomicity and ordering of the
access, so using set/clear_bit() is replaced with simple masks.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Yury Norov 2017-08-20 13:20:47 +03:00 committed by Catalin Marinas
parent 828f193dd6
commit 5ce93ab624
3 changed files with 5 additions and 3 deletions
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4
arch/arm64/include/asm/elf.h
View File

@ -139,7 +139,7 @@ typedef struct user_fpsimd_state elf_fpregset_t;
#define SET_PERSONALITY(ex) \
({ \
clear_bit(TIF_32BIT, &current->mm->context.flags); \
current->mm->context.flags = 0; \
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); \
current->mm->context.flags = MMCF_AARCH32; \
set_thread_flag(TIF_32BIT); \
})
#define COMPAT_ARCH_DLINFO

2
arch/arm64/include/asm/mmu.h
View File

@ -16,6 +16,8 @@
#ifndef __ASM_MMU_H
#define __ASM_MMU_H
#define MMCF_AARCH32 0x1 /* mm context flag for AArch32 executables */
typedef struct {
atomic64_t id;
void *vdso;

2
arch/arm64/kernel/probes/uprobes.c
View File

@ -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 (mm->context.flags & MMCF_AARCH32)
return -ENOTSUPP;
else if (!IS_ALIGNED(addr, AARCH64_INSN_SIZE))
return -EINVAL;