From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751464AbaBLG4Q (ORCPT ); Wed, 12 Feb 2014 01:56:16 -0500 Received: from szxga01-in.huawei.com ([119.145.14.64]:25483 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750763AbaBLG4P (ORCPT ); Wed, 12 Feb 2014 01:56:15 -0500 Message-ID: <52FB1AAA.9030108@huawei.com> Date: Wed, 12 Feb 2014 14:54:34 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Ben Dooks CC: , , , Catalin Marinas , "Li Zefan" , Wang Nan , , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: [PATCH] ARM: mm: support big-endian page tables References: <52F9EB40.1030703@huawei.com> <52F9FE1A.6000607@codethink.co.uk> In-Reply-To: <52F9FE1A.6000607@codethink.co.uk> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.24.155] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014/2/11 18:40, Ben Dooks wrote: > On 11/02/14 09:20, Jianguo Wu wrote: >> When enable LPAE and big-endian in a hisilicon board, while specify >> mem=384M mem=512M@7680M, will get bad page state: >> >> Freeing unused kernel memory: 180K (c0466000 - c0493000) >> BUG: Bad page state in process init pfn:fa442 >> page:c7749840 count:0 mapcount:-1 mapping: (null) index:0x0 >> page flags: 0x40000400(reserved) >> Modules linked in: >> CPU: 0 PID: 1 Comm: init Not tainted 3.10.27+ #66 >> [] (unwind_backtrace+0x0/0x11c) from [] (show_stack+0x10/0x14) >> [] (show_stack+0x10/0x14) from [] (bad_page+0xd4/0x104) >> [] (bad_page+0xd4/0x104) from [] (free_pages_prepare+0xa8/0x14c) >> [] (free_pages_prepare+0xa8/0x14c) from [] (free_hot_cold_page+0x18/0xf0) >> [] (free_hot_cold_page+0x18/0xf0) from [] (handle_pte_fault+0xcf4/0xdc8) >> [] (handle_pte_fault+0xcf4/0xdc8) from [] (handle_mm_fault+0xf4/0x120) >> [] (handle_mm_fault+0xf4/0x120) from [] (do_page_fault+0xfc/0x354) >> [] (do_page_fault+0xfc/0x354) from [] (do_DataAbort+0x2c/0x90) >> [] (do_DataAbort+0x2c/0x90) from [] (__dabt_usr+0x34/0x40) >> >> The bad pfn:fa442 is not system memory(mem=384M mem=512M@7680M), after debugging, >> I find in page fault handler, will get wrong pfn from pte just after set pte, >> as follow: >> do_anonymous_page() >> { >> ... >> set_pte_at(mm, address, page_table, entry); >> >> //debug code >> pfn = pte_pfn(entry); >> pr_info("pfn:0x%lx, pte:0x%llx\n", pfn, pte_val(entry)); >> >> //read out the pte just set >> new_pte = pte_offset_map(pmd, address); >> new_pfn = pte_pfn(*new_pte); >> pr_info("new pfn:0x%lx, new pte:0x%llx\n", pfn, pte_val(entry)); >> ... >> } > > Thanks, must have missed tickling this one. > >> >> pfn: 0x1fa4f5, pte:0xc00001fa4f575f >> new_pfn:0xfa4f5, new_pte:0xc00000fa4f5f5f //new pfn/pte is wrong. >> >> The bug is happened in cpu_v7_set_pte_ext(ptep, pte): >> when pte is 64-bit, for little-endian, will store low 32-bit in r2, >> high 32-bit in r3; for big-endian, will store low 32-bit in r3, >> high 32-bit in r2, this will cause wrong pfn stored in pte, >> so we should exchange r2 and r3 for big-endian. >> >> Signed-off-by: Jianguo Wu >> --- >> arch/arm/mm/proc-v7-3level.S | 10 ++++++++++ >> 1 files changed, 10 insertions(+), 0 deletions(-) >> >> diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S >> index 6ba4bd9..71b3892 100644 >> --- a/arch/arm/mm/proc-v7-3level.S >> +++ b/arch/arm/mm/proc-v7-3level.S >> @@ -65,6 +65,15 @@ ENDPROC(cpu_v7_switch_mm) >> */ >> ENTRY(cpu_v7_set_pte_ext) >> #ifdef CONFIG_MMU >> +#ifdef CONFIG_CPU_ENDIAN_BE8 >> + tst r3, #L_PTE_VALID >> + beq 1f >> + tst r2, #1 << (57 - 32) @ L_PTE_NONE >> + bicne r3, #L_PTE_VALID >> + bne 1f >> + tst r2, #1 << (55 - 32) @ L_PTE_DIRTY >> + orreq r3, #L_PTE_RDONLY >> +#else >> tst r2, #L_PTE_VALID >> beq 1f >> tst r3, #1 << (57 - 32) @ L_PTE_NONE >> @@ -72,6 +81,7 @@ ENTRY(cpu_v7_set_pte_ext) >> bne 1f >> tst r3, #1 << (55 - 32) @ L_PTE_DIRTY >> orreq r2, #L_PTE_RDONLY >> +#endif >> 1: strd r2, r3, [r0] >> ALT_SMP(W(nop)) >> ALT_UP (mcr p15, 0, r0, c7, c10, 1) @ flush_pte >> -- 1.7.1 > > If possible can we avoid large #ifdef blocks here? > > Two ideas are > > ARM_LE(tst r2, #L_PTE_VALID) > ARM_BE(tst r3, #L_PTE_VALID) > > or change r2, r3 pair to say rlow, rhi and > > #ifdef CONFIG_CPU_ENDIAN_BE8 > #define rlow r3 > #define rhi r2 > #else > #define rlow r2 > #define rhi r3 > #endif > Hi Ben, Thanks for your suggestion, how about this? Signed-off-by: Jianguo Wu --- arch/arm/mm/proc-v7-3level.S | 18 +++++++++++++----- 1 files changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S index 01a719e..22e3ad6 100644 --- a/arch/arm/mm/proc-v7-3level.S +++ b/arch/arm/mm/proc-v7-3level.S @@ -64,6 +64,14 @@ ENTRY(cpu_v7_switch_mm) mov pc, lr ENDPROC(cpu_v7_switch_mm) +#ifdef __ARMEB__ +#define rl r3 +#define rh r2 +#else +#define rl r2 +#define rh r3 +#endif + /* * cpu_v7_set_pte_ext(ptep, pte) * @@ -73,13 +81,13 @@ ENDPROC(cpu_v7_switch_mm) */ ENTRY(cpu_v7_set_pte_ext) #ifdef CONFIG_MMU - tst r2, #L_PTE_VALID + tst rl, #L_PTE_VALID beq 1f - tst r3, #1 << (57 - 32) @ L_PTE_NONE - bicne r2, #L_PTE_VALID + tst rh, #1 << (57 - 32) @ L_PTE_NONE + bicne rl, #L_PTE_VALID bne 1f - tst r3, #1 << (55 - 32) @ L_PTE_DIRTY - orreq r2, #L_PTE_RDONLY + tst rh, #1 << (55 - 32) @ L_PTE_DIRTY + orreq rl, #L_PTE_RDONLY 1: strd r2, r3, [r0] ALT_SMP(W(nop)) ALT_UP (mcr p15, 0, r0, c7, c10, 1) @ flush_pte -- 1.7.1 Thanks, Jianguo Wu > >