[PATCH V3 5/6] arm64: introduce mm context flag to keep 32 bit task information

Pratyush Anand
2016-11-02T09:11:26Z

We need to decide in some cases like uprobe instruction analysis that
whether the current mm context belongs to a 32 bit task or 64 bit.

This patch has introduced an unsigned flag variable in mm_context_t.
Currently, we set and clear TIF_32BIT depending on the condition that
whether an elf binary load sets personality for 32 bit or 64 bit
respectively.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/arm64/include/asm/elf.h | 12 ++++++++++--
arch/arm64/include/asm/mmu.h | 1 +
2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index a55384f4a5d7..5d1700425efe 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -138,7 +138,11 @@ typedef struct user_fpsimd_state elf_fpregset_t;
*/
#define ELF_PLAT_INIT(_r, load_addr) (_r)->regs[0] = 0

-#define SET_PERSONALITY(ex) clear_thread_flag(TIF_32BIT);
+#define SET_PERSONALITY(ex) \
+({ \
+ clear_bit(TIF_32BIT, &current->mm->context.flags); \
+ clear_thread_flag(TIF_32BIT); \
+})

/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
#define ARCH_DLINFO \
@@ -183,7 +187,11 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG];
((x)->e_flags & EF_ARM_EABI_MASK))

#define compat_start_thread compat_start_thread
-#define COMPAT_SET_PERSONALITY(ex) set_thread_flag(TIF_32BIT);
+#define COMPAT_SET_PERSONALITY(ex) \
+({ \
+ set_bit(TIF_32BIT, &current->mm->context.flags); \
+ set_thread_flag(TIF_32BIT); \
+ })
#define COMPAT_ARCH_DLINFO
extern int aarch32_setup_vectors_page(struct linux_binprm *bprm,
int uses_interp);
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 8d9fce037b2f..d4fa21543771 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -19,6 +19,7 @@
typedef struct {
atomic64_t id;
void *vdso;
+ unsigned long flags;
} mm_context_t;

/*
--
2.7.4