Commit 5f1888a0 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/fault: Perform exception fixup in do_page_fault() 



Exception fixup doesn't require the heady full regs saving,
do it from do_page_fault() directly.

For that, split bad_page_fault() in two parts.

As bad_page_fault() can also be called from other places than
handle_page_fault(), it will still perform exception fixup and
fallback on __bad_page_fault().

handle_page_fault() directly calls __bad_page_fault() as the
exception fixup will now be done by do_page_fault()

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bd07d6fef9237614cd6d318d8f19faeeadaa816b.1607491748.git.christophe.leroy@csgroup.eu
parent cbd7e6ca

arch/powerpc/include/asm/bug.h

+1 −0
Original line number Diff line number Diff line
@@ -113,6 +113,7 @@ 
struct pt_regs;

extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);

extern void bad_page_fault(struct pt_regs *, unsigned long, int);

void __bad_page_fault(struct pt_regs *regs, unsigned long address, int sig);

extern void _exception(int, struct pt_regs *, int, unsigned long);

extern void _exception_pkey(struct pt_regs *, unsigned long, int);

extern void die(const char *, struct pt_regs *, long);

arch/powerpc/kernel/entry_32.S

+1 −1
Original line number Diff line number Diff line
@@ -684,7 +684,7 @@ handle_page_fault: 
	mr	r5,r3

	addi	r3,r1,STACK_FRAME_OVERHEAD

	lwz	r4,_DAR(r1)

	bl	bad_page_fault

	bl	__bad_page_fault

	b	ret_from_except_full



#ifdef CONFIG_PPC_BOOK3S_32

arch/powerpc/kernel/exceptions-64e.S

+1 −1
Original line number Diff line number Diff line
@@ -1023,7 +1023,7 @@ storage_fault_common: 
	mr	r5,r3

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r4,_DAR(r1)

	bl	bad_page_fault

	bl	__bad_page_fault

	b	ret_from_except



/*

arch/powerpc/kernel/exceptions-64s.S

+1 −1
Original line number Diff line number Diff line
@@ -3259,7 +3259,7 @@ handle_page_fault: 
	mr	r5,r3

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r4,_DAR(r1)

	bl	bad_page_fault

	bl	__bad_page_fault

	b	interrupt_return



/* We have a data breakpoint exception - handle it */

arch/powerpc/mm/fault.c

+24 −9
Original line number Diff line number Diff line
@@ -545,10 +545,20 @@ NOKPROBE_SYMBOL(__do_page_fault); 
int do_page_fault(struct pt_regs *regs, unsigned long address,

		  unsigned long error_code)

{

	const struct exception_table_entry *entry;

	enum ctx_state prev_state = exception_enter();

	int rc = __do_page_fault(regs, address, error_code);

	exception_exit(prev_state);

	if (likely(!rc))

		return 0;



	entry = search_exception_tables(regs->nip);

	if (unlikely(!entry))

		return rc;



	instruction_pointer_set(regs, extable_fixup(entry));



	return 0;

}

NOKPROBE_SYMBOL(do_page_fault);
@@ -557,17 +567,10 @@ NOKPROBE_SYMBOL(do_page_fault); 
 * It is called from the DSI and ISI handlers in head.S and from some

 * of the procedures in traps.c.

 */

void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)

void __bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)

{

	const struct exception_table_entry *entry;

	int is_write = page_fault_is_write(regs->dsisr);



	/* Are we prepared to handle this fault?  */

	if ((entry = search_exception_tables(regs->nip)) != NULL) {

		regs->nip = extable_fixup(entry);

		return;

	}



	/* kernel has accessed a bad area */



	switch (TRAP(regs)) {
@@ -601,3 +604,15 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) 


	die("Kernel access of bad area", regs, sig);

}



void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)

{

	const struct exception_table_entry *entry;



	/* Are we prepared to handle this fault?  */

	entry = search_exception_tables(instruction_pointer(regs));

	if (entry)

		instruction_pointer_set(regs, extable_fixup(entry));

	else

		__bad_page_fault(regs, address, sig);

}

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