diff options
| -rw-r--r-- | arch/powerpc/include/asm/interrupt.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/mm/book3s64/hash_utils.c | 54 | ||||
| -rw-r--r-- | arch/powerpc/perf/callchain.h | 9 | ||||
| -rw-r--r-- | arch/powerpc/perf/callchain_64.c | 27 |
4 files changed, 10 insertions, 82 deletions
diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h index fc28f46d2f9d..5404f7abbcf8 100644 --- a/arch/powerpc/include/asm/interrupt.h +++ b/arch/powerpc/include/asm/interrupt.h @@ -612,7 +612,7 @@ DECLARE_INTERRUPT_HANDLER_RAW(do_slb_fault); DECLARE_INTERRUPT_HANDLER(do_bad_segment_interrupt); /* hash_utils.c */ -DECLARE_INTERRUPT_HANDLER_RAW(do_hash_fault); +DECLARE_INTERRUPT_HANDLER(do_hash_fault); /* fault.c */ DECLARE_INTERRUPT_HANDLER(do_page_fault); diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index 7abf82a698d3..985cabdd7f67 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -1621,8 +1621,7 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap, } EXPORT_SYMBOL_GPL(hash_page); -DECLARE_INTERRUPT_HANDLER(__do_hash_fault); -DEFINE_INTERRUPT_HANDLER(__do_hash_fault) +DEFINE_INTERRUPT_HANDLER(do_hash_fault) { unsigned long ea = regs->dar; unsigned long dsisr = regs->dsisr; @@ -1681,35 +1680,6 @@ DEFINE_INTERRUPT_HANDLER(__do_hash_fault) } } -/* - * The _RAW interrupt entry checks for the in_nmi() case before - * running the full handler. - */ -DEFINE_INTERRUPT_HANDLER_RAW(do_hash_fault) -{ - /* - * If we are in an "NMI" (e.g., an interrupt when soft-disabled), then - * don't call hash_page, just fail the fault. This is required to - * prevent re-entrancy problems in the hash code, namely perf - * interrupts hitting while something holds H_PAGE_BUSY, and taking a - * hash fault. See the comment in hash_preload(). - * - * We come here as a result of a DSI at a point where we don't want - * to call hash_page, such as when we are accessing memory (possibly - * user memory) inside a PMU interrupt that occurred while interrupts - * were soft-disabled. We want to invoke the exception handler for - * the access, or panic if there isn't a handler. - */ - if (unlikely(in_nmi())) { - do_bad_page_fault_segv(regs); - return 0; - } - - __do_hash_fault(regs); - - return 0; -} - #ifdef CONFIG_PPC_MM_SLICES static bool should_hash_preload(struct mm_struct *mm, unsigned long ea) { @@ -1776,26 +1746,18 @@ static void hash_preload(struct mm_struct *mm, pte_t *ptep, unsigned long ea, #endif /* CONFIG_PPC_64K_PAGES */ /* - * __hash_page_* must run with interrupts off, as it sets the - * H_PAGE_BUSY bit. It's possible for perf interrupts to hit at any - * time and may take a hash fault reading the user stack, see - * read_user_stack_slow() in the powerpc/perf code. - * - * If that takes a hash fault on the same page as we lock here, it - * will bail out when seeing H_PAGE_BUSY set, and retry the access - * leading to an infinite loop. + * __hash_page_* must run with interrupts off, including PMI interrupts + * off, as it sets the H_PAGE_BUSY bit. * - * Disabling interrupts here does not prevent perf interrupts, but it - * will prevent them taking hash faults (see the NMI test in - * do_hash_page), then read_user_stack's copy_from_user_nofault will - * fail and perf will fall back to read_user_stack_slow(), which - * walks the Linux page tables. + * It's otherwise possible for perf interrupts to hit at any time and + * may take a hash fault reading the user stack, which could take a + * hash miss and deadlock on the same H_PAGE_BUSY bit. * * Interrupts must also be off for the duration of the * mm_is_thread_local test and update, to prevent preempt running the * mm on another CPU (XXX: this may be racy vs kthread_use_mm). */ - local_irq_save(flags); + powerpc_local_irq_pmu_save(flags); /* Is that local to this CPU ? */ if (mm_is_thread_local(mm)) @@ -1820,7 +1782,7 @@ static void hash_preload(struct mm_struct *mm, pte_t *ptep, unsigned long ea, mm_ctx_user_psize(&mm->context), pte_val(*ptep)); - local_irq_restore(flags); + powerpc_local_irq_pmu_restore(flags); } /* diff --git a/arch/powerpc/perf/callchain.h b/arch/powerpc/perf/callchain.h index d6fa6e25234f..19a8d051ddf1 100644 --- a/arch/powerpc/perf/callchain.h +++ b/arch/powerpc/perf/callchain.h @@ -2,7 +2,6 @@ #ifndef _POWERPC_PERF_CALLCHAIN_H #define _POWERPC_PERF_CALLCHAIN_H -int read_user_stack_slow(const void __user *ptr, void *buf, int nb); void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs); void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry, @@ -26,17 +25,11 @@ static inline int __read_user_stack(const void __user *ptr, void *ret, size_t size) { unsigned long addr = (unsigned long)ptr; - int rc; if (addr > TASK_SIZE - size || (addr & (size - 1))) return -EFAULT; - rc = copy_from_user_nofault(ret, ptr, size); - - if (IS_ENABLED(CONFIG_PPC64) && !radix_enabled() && rc) - return read_user_stack_slow(ptr, ret, size); - - return rc; + return copy_from_user_nofault(ret, ptr, size); } #endif /* _POWERPC_PERF_CALLCHAIN_H */ diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c index 8d0df4226328..488e8a21a11e 100644 --- a/arch/powerpc/perf/callchain_64.c +++ b/arch/powerpc/perf/callchain_64.c @@ -18,33 +18,6 @@ #include "callchain.h" -/* - * On 64-bit we don't want to invoke hash_page on user addresses from - * interrupt context, so if the access faults, we read the page tables - * to find which page (if any) is mapped and access it directly. Radix - * has no need for this so it doesn't use read_user_stack_slow. - */ -int read_user_stack_slow(const void __user *ptr, void *buf, int nb) -{ - - unsigned long addr = (unsigned long) ptr; - unsigned long offset; - struct page *page; - void *kaddr; - - if (get_user_page_fast_only(addr, FOLL_WRITE, &page)) { - kaddr = page_address(page); - - /* align address to page boundary */ - offset = addr & ~PAGE_MASK; - - memcpy(buf, kaddr + offset, nb); - put_page(page); - return 0; - } - return -EFAULT; -} - static int read_user_stack_64(const unsigned long __user *ptr, unsigned long *ret) { return __read_user_stack(ptr, ret, sizeof(*ret)); |