arm64: introduce mm context flag to keep 32 bit task information

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>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index a55384f..5d17004 100644 (file)
--- 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 a81454a..4761941 100644 (file)
--- 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;
 
 /*