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powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

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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: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add task_stack.h to livepatch.h to fix build fails]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy
2019-01-31 10:08:58 +00:00
committed by Michael Ellerman
parent 7aef376679
commit ed1cd6deb0
21 changed files with 56 additions and 194 deletions
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17
arch/powerpc/include/asm/smp.h
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@@ -83,7 +83,22 @@ int is_cpu_dead(unsigned int cpu);
/* 32-bit */
extern int smp_hw_index[];
#define raw_smp_processor_id() (current_thread_info()->cpu)
/*
* This is particularly ugly: it appears we can't actually get the definition
* of task_struct here, but we need access to the CPU this task is running on.
* Instead of using task_struct we're using _TASK_CPU which is extracted from
* asm-offsets.h by kbuild to get the current processor ID.
*
* This also needs to be safeguarded when building asm-offsets.s because at
* that time _TASK_CPU is not defined yet. It could have been guarded by
* _TASK_CPU itself, but we want the build to fail if _TASK_CPU is missing
* when building something else than asm-offsets.s
*/
#ifdef GENERATING_ASM_OFFSETS
#define raw_smp_processor_id() (0)
#else
#define raw_smp_processor_id() (*(unsigned int *)((void *)current + _TASK_CPU))
#endif
#define hard_smp_processor_id() (smp_hw_index[smp_processor_id()])
static inline int get_hard_smp_processor_id(int cpu)