• Christophe Leroy's avatar
    powerpc: Activate CONFIG_THREAD_INFO_IN_TASK · ed1cd6de
    Christophe Leroy authored
    This patch activates CONFIG_THREAD_INFO_IN_TASK which
    moves the thread_info into task_struct.
    
    Moving thread_info into task_struct has the following advantages:
      - It protects thread_info from corruption in the case of stack
        overflows.
      - Its address is harder to determine if stack addresses are leaked,
        making a number of attacks more difficult.
    
    This has the following consequences:
      - thread_info is now located at the beginning of task_struct.
      - The 'cpu' field is now in task_struct, and only exists when
        CONFIG_SMP is active.
      - thread_info doesn't have anymore the 'task' field.
    
    This patch:
      - Removes all recopy of thread_info struct when the stack changes.
      - Changes the CURRENT_THREAD_INFO() macro to point to current.
      - Selects CONFIG_THREAD_INFO_IN_TASK.
      - Modifies raw_smp_processor_id() to get ->cpu from current without
        including linux/sched.h to avoid circular inclusion and without
        including asm/asm-offsets.h to avoid symbol names duplication
        between ASM constants and C constants.
      - Modifies klp_init_thread_info() to take a task_struct pointer
        argument.
    Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
    Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
    [mpe: Add task_stack.h to livepatch.h to fix build fails]
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    ed1cd6de
head_44x.S 32.7 KB