From b5c8f0fd595d25a938d16c041f92badc67533d9f Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Wed, 19 Jul 2017 14:49:36 +1000 Subject: [PATCH] powerpc/mm: Rework mm_fault_error() First, handle the normal retry failure in do_page_fault itself, since it's a simple return statement. That allows us to remove the "continue" special return code from mm_fault_error(). Once that's done, we can have an implementation much closer to x86 where we only call mm_fault_error() if VM_FAULT_ERROR is set and directly return. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman --- arch/powerpc/mm/fault.c | 66 +++++++++++++++++------------------------ 1 file changed, 28 insertions(+), 38 deletions(-) diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 3903b55fccf8..0b217947d34f 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -147,10 +147,6 @@ static noinline int bad_area(struct pt_regs *regs, unsigned long address) return __bad_area(regs, address, SEGV_MAPERR); } -#define MM_FAULT_RETURN 0 -#define MM_FAULT_CONTINUE -1 -#define MM_FAULT_ERR(sig) (sig) - static int do_sigbus(struct pt_regs *regs, unsigned long address, unsigned int fault) { @@ -158,7 +154,7 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address, unsigned int lsb = 0; if (!user_mode(regs)) - return MM_FAULT_ERR(SIGBUS); + return SIGBUS; current->thread.trap_nr = BUS_ADRERR; info.si_signo = SIGBUS; @@ -179,25 +175,17 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address, #endif info.si_addr_lsb = lsb; force_sig_info(SIGBUS, &info, current); - return MM_FAULT_RETURN; + return 0; } static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault) { /* - * Pagefault was interrupted by SIGKILL. We have no reason to - * continue the pagefault. + * Kernel page fault interrupted by SIGKILL. We have no reason to + * continue processing. */ - if (fatal_signal_pending(current)) { - /* Coming from kernel, we need to deal with uaccess fixups */ - if (user_mode(regs)) - return MM_FAULT_RETURN; - return MM_FAULT_ERR(SIGKILL); - } - - /* No fault: be happy */ - if (!(fault & VM_FAULT_ERROR)) - return MM_FAULT_CONTINUE; + if (fatal_signal_pending(current) && !user_mode(regs)) + return SIGKILL; /* Out of memory */ if (fault & VM_FAULT_OOM) { @@ -206,17 +194,18 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault) * made us unable to handle the page fault gracefully. */ if (!user_mode(regs)) - return MM_FAULT_ERR(SIGKILL); + return SIGSEGV; pagefault_out_of_memory(); - return MM_FAULT_RETURN; + } else { + if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| + VM_FAULT_HWPOISON_LARGE)) + return do_sigbus(regs, addr, fault); + else if (fault & VM_FAULT_SIGSEGV) + return bad_area_nosemaphore(regs, addr); + else + BUG(); } - - if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) - return do_sigbus(regs, addr, fault); - - /* We don't understand the fault code, this is fatal */ - BUG(); - return MM_FAULT_CONTINUE; + return 0; } /* Is this a bad kernel fault ? */ @@ -274,7 +263,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, int is_user = user_mode(regs); int is_write = page_fault_is_write(error_code); int fault; - int rc = 0, store_update_sp = 0; + int store_update_sp = 0; #ifdef CONFIG_PPC_ICSWX /* @@ -283,7 +272,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address, * look at it */ if (error_code & ICSWX_DSI_UCT) { - rc = acop_handle_fault(regs, address, error_code); + int rc = acop_handle_fault(regs, address, error_code); if (rc) return rc; } @@ -492,18 +481,19 @@ good_area: if (!fatal_signal_pending(current)) goto retry; } - /* We will enter mm_fault_error() below */ - } else - up_read(¤t->mm->mmap_sem); - if (unlikely(fault & (VM_FAULT_RETRY|VM_FAULT_ERROR))) { - if (fault & VM_FAULT_SIGSEGV) - return bad_area_nosemaphore(regs, address); - rc = mm_fault_error(regs, address, fault); - if (rc >= MM_FAULT_RETURN) - return rc; + /* + * User mode? Just return to handle the fatal exception otherwise + * return to bad_page_fault + */ + return is_user ? 0 : SIGBUS; } + up_read(¤t->mm->mmap_sem); + + if (unlikely(fault & VM_FAULT_ERROR)) + return mm_fault_error(regs, address, fault); + /* * Major/minor page fault accounting. */ -- 2.30.2