s390/vdso: avoid 64-bit vdso mapping for compat tasks

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vdso_fault used is_compat_task function (on s390 it tests "current"
thread_info flags) to distinguish compat tasks and map 31-bit vdso
pages. But "current" task might not correspond to mm context.

When 31-bit compat inferior is executed under gdb, gdb does
PTRACE_PEEKTEXT on vdso page, causing vdso_fault with "current" being
64-bit gdb process. So, 31-bit inferior ends up with 64-bit vdso mapped.

To avoid this problem a new compat_mm flag has been introduced into
mm context. This flag is used in vdso_fault and vdso_mremap instead
of is_compat_task.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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This commit is contained in:

Vasily Gorbik 2018-09-14 17:29:39 +02:00 • committed by Martin Schwidefsky

parent 1c472d4628

commit d1befa6582

3 changed files with 8 additions and 3 deletions

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2

arch/s390/include/asm/mmu.h

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1

arch/s390/include/asm/mmu_context.h

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8

arch/s390/kernel/vdso.c

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