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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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5
arch/powerpc/net/bpf_jit32.h
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@@ -106,9 +106,8 @@ DECLARE_LOAD_FUNC(sk_load_byte_msh);
} while (0)
#else
#define PPC_BPF_LOAD_CPU(r) \
do { BUILD_BUG_ON(FIELD_SIZEOF(struct thread_info, cpu) != 4); \
PPC_LHZ_OFFS(r, (1 & ~(THREAD_SIZE - 1)), \
offsetof(struct thread_info, cpu)); \
do { BUILD_BUG_ON(FIELD_SIZEOF(struct task_struct, cpu) != 4); \
PPC_LHZ_OFFS(r, 2, offsetof(struct task_struct, cpu)); \
} while(0)
#endif
#else