This moves the 64s/hash context tracking from hash_page_mm() to
__do_hash_fault(), so it's no longer called by OCXL / SPU
accelerators, which was certainly the wrong thing to be doing,
because those callers are not low level interrupt handlers, so
should have entered a kernel context tracking already.
Then remain in kernel context for the duration of the fault,
rather than enter/exit for the hash fault then enter/exit for
the page fault, which is pointless.
Even still, calling exception_enter/exit in __do_hash_fault seems
questionable because that's touching per-cpu variables, tracing,
etc., which might have been interrupted by this hash fault or
themselves cause hash faults. But maybe I miss something because
hash_page_mm very deliberately calls trace_hash_fault too, for
example. So for now go with it, it's no worse than before, in this
regard.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/bug.h | 1 +
arch/powerpc/mm/book3s64/hash_utils.c | 7 ++++---
arch/powerpc/mm/fault.c | 30 +++++++++++++++++++++------
3 files changed, 29 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
index c10ae0a9bbaf..d1635ffbb179 100644
--- a/arch/powerpc/include/asm/bug.h
+++ b/arch/powerpc/include/asm/bug.h
@@ -112,6 +112,7 @@
struct pt_regs;
long do_page_fault(struct pt_regs *);
+long hash__do_page_fault(struct pt_regs *);
void bad_page_fault(struct pt_regs *, int);
void __bad_page_fault(struct pt_regs *regs, int sig);
void do_bad_page_fault_segv(struct pt_regs *regs);
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c
b/arch/powerpc/mm/book3s64/hash_utils.c
index 824fcb2627e4..b7b78aeea3eb 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -1289,7 +1289,6 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
unsigned long flags)
{
bool is_thp;
- enum ctx_state prev_state = exception_enter();
pgd_t *pgdir;
unsigned long vsid;
pte_t *ptep;
@@ -1491,7 +1490,6 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea,
DBG_LOW(" -> rc=%d\n", rc);
bail:
- exception_exit(prev_state);
return rc;
}
EXPORT_SYMBOL_GPL(hash_page_mm);
@@ -1515,6 +1513,7 @@ EXPORT_SYMBOL_GPL(hash_page);
DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
{
+ enum ctx_state prev_state = exception_enter();
unsigned long ea = regs->dar;
unsigned long dsisr = regs->dsisr;
unsigned long access = _PAGE_PRESENT | _PAGE_READ;
@@ -1563,6 +1562,8 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault)
err = 0;
}
+ exception_exit(prev_state);
+
return err;
}
@@ -1599,7 +1600,7 @@ DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault)
err = __do_hash_fault(regs);
if (err) {
page_fault:
- err = do_page_fault(regs);
+ err = hash__do_page_fault(regs);
}
return err;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index eef7281507f9..620ff623b2c6 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -387,7 +387,7 @@ static void sanity_check_fault(bool is_write, bool is_user,
* The return value is 0 if the fault was handled, or the signal
* number if this is a kernel fault that can't be handled here.
*/
-static int __do_page_fault(struct pt_regs *regs, unsigned long address,
+static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
unsigned long error_code)
{
struct vm_area_struct * vma;
@@ -537,15 +537,13 @@ static int __do_page_fault(struct pt_regs *regs, unsigned
long address,
return 0;
}
-NOKPROBE_SYMBOL(__do_page_fault);
+NOKPROBE_SYMBOL(___do_page_fault);
-DEFINE_INTERRUPT_HANDLER_RET(do_page_fault)
+static long __do_page_fault(struct pt_regs *regs)
{
- enum ctx_state prev_state;
long err;
- prev_state = exception_enter();
- err = __do_page_fault(regs, regs->dar, regs->dsisr);
+ err = ___do_page_fault(regs, regs->dar, regs->dsisr);
if (unlikely(err)) {
const struct exception_table_entry *entry;
@@ -560,12 +558,32 @@ DEFINE_INTERRUPT_HANDLER_RET(do_page_fault)
}
}
+ return err;
+}
+NOKPROBE_SYMBOL(__do_page_fault);
+
+DEFINE_INTERRUPT_HANDLER_RET(do_page_fault)
+{
+ enum ctx_state prev_state = exception_enter();
+ long err;
+
+ err = __do_page_fault(regs);
+
exception_exit(prev_state);
return err;
}
NOKPROBE_SYMBOL(do_page_fault);
+#ifdef CONFIG_PPC_BOOK3S_64
+/* Same as do_page_fault but interrupt entry has already run in do_hash_fault
*/
+long hash__do_page_fault(struct pt_regs *regs)
+{
+ return __do_page_fault(regs);
+}
+NOKPROBE_SYMBOL(hash__do_page_fault);
+#endif
+
/*
* bad_page_fault is called when we have a bad access from the kernel.
* It is called from the DSI and ISI handlers in head.S and from some
--
2.23.0
