powerpc/32: Warn and return ENOSYS on syscalls from kernel

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Since commit b86fb88855 ("powerpc/32: implement fast entry for
syscalls on non BOOKE") and commit 1a4b739bbb ("powerpc/32:
implement fast entry for syscalls on BOOKE"), syscalls from
kernel are unexpected and can have catastrophic consequences
as it will destroy the kernel stack.

Test MSR_PR on syscall entry. In case syscall is from kernel,
emit a warning and return ENOSYS error.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8ee3bdbbdfdfc64ca7001e90c43b2aee6f333578.1580470482.git.christophe.leroy@c-s.fr

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This commit is contained in:

Christophe Leroy 2020-01-31 11:34:54 +00:00 • committed by Michael Ellerman

parent 030e347430

commit 9e27086292

3 changed files with 40 additions and 8 deletions

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27

arch/powerpc/kernel/entry_32.S

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16

arch/powerpc/kernel/head_32.h

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5

arch/powerpc/kernel/head_booke.h

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