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Message-Id: <1997d67070847346bc1d55a7e51f23991e4b73ad.1607416578.git.christophe.leroy@csgroup.eu>
Date: Tue, 8 Dec 2020 08:37:02 +0000 (UTC)
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>, npiggin@...il.com,
aneesh.kumar@...ux.ibm.com
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v3 5/5] 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()
Reviewed-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v2: Add prototype of __bad_page_fault() in asm/bug.h
---
arch/powerpc/include/asm/bug.h | 1 +
arch/powerpc/kernel/entry_32.S | 2 +-
arch/powerpc/kernel/exceptions-64e.S | 2 +-
arch/powerpc/kernel/exceptions-64s.S | 2 +-
arch/powerpc/mm/fault.c | 33 ++++++++++++++++++++--------
5 files changed, 28 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index ba0500872cce..464f8ca8a5c9 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -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);
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 58177c71dfd4..1c9b0ccc2172 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -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
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index f579ce46eef2..74d07dc0bb48 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -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
/*
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 1c8f1b90e174..e02ad6fefa46 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -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 */
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 1770b41e4730..2e50bc1c3783 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -538,10 +538,20 @@ 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);
- return rc;
+ 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);
@@ -550,17 +560,10 @@ 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)) {
@@ -594,3 +597,15 @@ 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);
+}
--
2.25.0
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