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powerpc/32: prepare for CONFIG_VMAP_STACK

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To support CONFIG_VMAP_STACK, the kernel has to activate Data MMU
Translation for accessing the stack. Before doing that it must save
SRR0, SRR1 and also DAR and DSISR when relevant, in order to not
loose them in case there is a Data TLB Miss once the translation is
reactivated.

This patch adds fields in thread struct for saving those registers.
It prepares entry_32.S to handle exception entry with
Data MMU Translation enabled and alters EXCEPTION_PROLOG macros to
save SRR0, SRR1, DAR and DSISR then reenables Data MMU.

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/a775a1fea60f190e0f63503463fb775310a2009b.1576916812.git.christophe.leroy@c-s.fr
This commit is contained in:
Christophe Leroy
2019-12-21 08:32:27 +00:00
committed by Michael Ellerman
parent c9c84fd945
commit 028474876f
5 changed files with 133 additions and 16 deletions
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6
arch/powerpc/kernel/asm-offsets.c
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@@ -127,6 +127,12 @@ int main(void)
OFFSET(KSP_VSID, thread_struct, ksp_vsid);
#else /* CONFIG_PPC64 */
OFFSET(PGDIR, thread_struct, pgdir);
#ifdef CONFIG_VMAP_STACK
OFFSET(SRR0, thread_struct, srr0);
OFFSET(SRR1, thread_struct, srr1);
OFFSET(DAR, thread_struct, dar);
OFFSET(DSISR, thread_struct, dsisr);
#endif
#ifdef CONFIG_SPE
OFFSET(THREAD_EVR0, thread_struct, evr[0]);
OFFSET(THREAD_ACC, thread_struct, acc);