From a008f8f9fd67ffb13d906ef4ea6235a3d62dfdb6 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Sat, 30 Jan 2021 23:08:41 +1000 Subject: powerpc/64s/hash: improve context tracking of hash faults 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 Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210130130852.2952424-32-npiggin@gmail.com --- arch/powerpc/mm/book3s64/hash_utils.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'arch/powerpc/mm/book3s64') diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index cf167f6d825d..d681dc5a7b1c 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); @@ -1516,6 +1514,7 @@ EXPORT_SYMBOL_GPL(hash_page); DECLARE_INTERRUPT_HANDLER_RET(__do_hash_fault); 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; @@ -1564,6 +1563,8 @@ DEFINE_INTERRUPT_HANDLER_RET(__do_hash_fault) err = 0; } + exception_exit(prev_state); + return err; } @@ -1600,7 +1601,7 @@ 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; -- cgit v1.2.3