Le 10/11/2020 à 09:29, Nicholas Piggin a écrit :

Excerpts from Christophe Leroy's message of November 6, 2020 5:59 pm:

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Le 05/11/2020 à 15:34, Nicholas Piggin a écrit :

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Make mm fault handlers all just take the pt_regs * argument and load
DAR/DSISR from that. Make those that return a value return long.

This is done to make the function signatures match other handlers, which
will help with a future patch to add wrappers. Explicit arguments could
be added for performance but that would require more wrapper macro
variants.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
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[...]

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diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index e65a49f246ef..390a296b16a3 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c

@@ -549,11 +549,12 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
   }
   NOKPROBE_SYMBOL(__do_page_fault);
   
-int do_page_fault(struct pt_regs *regs, unsigned long address,
-		  unsigned long error_code)
+long do_page_fault(struct pt_regs *regs)
   {
   	enum ctx_state prev_state = exception_enter();
-	int err;
+	unsigned long address = regs->dar;
+	unsigned long error_code = regs->dsisr;
+	long err;

By doing something more or less like this (need to be tuned for bookE as well):

+	int is_exec = TRAP(regs) == 0x400;
+	unsigned long address = is_exec ? regs->ssr0 : regs->dar;
+	unsigned long error_code = is_exec ? (regs->ssr1 & DSISR_SRR1_MATCH_32S) : regs->dsisr;

Ah, I didn't see that you saved these in srr0/1 already. Hmm, not in
pt_regs though. thread_struct (VMAP_STACK only)? exception_regs (booke
only)? Doesn't seem so easy.

Oops yes you are right, SRR0/SRR1 are not in pt_regs. And their validity in thread struct is rather 
short ... So forget my comment.

Christophe