powerpc/32: Change the stack protector canary value per task

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Partially copied from commit df0698be14 ("ARM: stack protector:
change the canary value per task")

A new random value for the canary is stored in the task struct whenever
a new task is forked.  This is meant to allow for different canary values
per task.  On powerpc, GCC expects the canary value to be found in a global
variable called __stack_chk_guard.  So this variable has to be updated
with the value stored in the task struct whenever a task switch occurs.

Because the variable GCC expects is global, this cannot work on SMP
unfortunately.  So, on SMP, the same initial canary value is kept
throughout, making this feature a bit less effective although it is still
useful.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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This commit is contained in:

Christophe Leroy 2016-11-22 11:49:32 +01:00 • committed by Michael Ellerman

parent 6533b7c16e

commit 902e06eb86

2 changed files with 8 additions and 1 deletions

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3

arch/powerpc/kernel/asm-offsets.c

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6

arch/powerpc/kernel/entry_32.S

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