linux-kernel - Re: [PATCH v4 02/14] arm: add support for folded p4d page tables

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <665dade8-727a-3318-6779-3998080da18f@samsung.com>
Date:   Mon, 11 May 2020 08:36:41 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Rich Felker <dalias@...c.org>, linux-ia64@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-sh@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linux-mm@...ck.org, Paul Mackerras <paulus@...ba.org>,
        linux-hexagon@...r.kernel.org, Will Deacon <will@...nel.org>,
        kvmarm@...ts.cs.columbia.edu, Jonas Bonn <jonas@...thpole.se>,
        linux-arch@...r.kernel.org, Brian Cain <bcain@...eaurora.org>,
        Marc Zyngier <maz@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Ley Foon Tan <ley.foon.tan@...el.com>,
        Catalin Marinas <catalin.marinas@....com>,
        uclinux-h8-devel@...ts.sourceforge.jp,
        Fenghua Yu <fenghua.yu@...el.com>,
        Arnd Bergmann <arnd@...db.de>, kvm-ppc@...r.kernel.org,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        openrisc@...ts.librecores.org, Stafford Horne <shorne@...il.com>,
        Guan Xuetao <gxt@....edu.cn>,
        linux-arm-kernel@...ts.infradead.org,
        Christophe Leroy <christophe.leroy@....fr>,
        Tony Luck <tony.luck@...el.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        nios2-dev@...ts.rocketboards.org, linuxppc-dev@...ts.ozlabs.org,
        Łukasz Stelmach <l.stelmach@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v4 02/14] arm: add support for folded p4d page tables

Hi Mike,

On 08.05.2020 19:42, Mike Rapoport wrote:
> On Fri, May 08, 2020 at 08:53:27AM +0200, Marek Szyprowski wrote:
>> On 07.05.2020 18:11, Mike Rapoport wrote:
>>> On Thu, May 07, 2020 at 02:16:56PM +0200, Marek Szyprowski wrote:
>>>> On 14.04.2020 17:34, Mike Rapoport wrote:
>>>>> From: Mike Rapoport <rppt@...ux.ibm.com>
>>>>>
>>>>> Implement primitives necessary for the 4th level folding, add walks of p4d
>>>>> level where appropriate, and remove __ARCH_USE_5LEVEL_HACK.
>>>>>
>>>>> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
>>>> Today I've noticed that kexec is broken on ARM 32bit. Bisecting between
>>>> current linux-next and v5.7-rc1 pointed to this commit. I've tested this
>>>> on Odroid XU4 and Raspberry Pi4 boards. Here is the relevant log:
>>>>
>>>> # kexec --kexec-syscall -l zImage --append "$(cat /proc/cmdline)"
>>>> memory_range[0]:0x40000000..0xbe9fffff
>>>> memory_range[0]:0x40000000..0xbe9fffff
>>>> # kexec -e
>>>> kexec_core: Starting new kernel
>>>> 8<--- cut here ---
>>>> Unable to handle kernel paging request at virtual address c010f1f4
>>>> pgd = c6817793
>>>> [c010f1f4] *pgd=4000041e(bad)
>>>> Internal error: Oops: 80d [#1] PREEMPT ARM
>>>> Modules linked in:
>>>> CPU: 0 PID: 1329 Comm: kexec Tainted: G        W
>>>> 5.7.0-rc3-00127-g6cba81ed0f62 #611
>>>> Hardware name: Samsung Exynos (Flattened Device Tree)
>>>> PC is at machine_kexec+0x40/0xfc
>>> Any chance you have the debug info in this kernel?
>>> scripts/faddr2line would come handy here.
>> # ./scripts/faddr2line --list vmlinux machine_kexec+0x40
>> machine_kexec+0x40/0xf8:
>>
>> machine_kexec at arch/arm/kernel/machine_kexec.c:182
>>    177            reboot_code_buffer =
>> page_address(image->control_code_page);
>>    178
>>    179            /* Prepare parameters for reboot_code_buffer*/
>>    180            set_kernel_text_rw();
>>    181            kexec_start_address = image->start;
>>   >182<           kexec_indirection_page = page_list;
>>    183            kexec_mach_type = machine_arch_type;
>>    184            kexec_boot_atags = image->arch.kernel_r2;
>>    185
>>    186            /* copy our kernel relocation code to the control code
>> page */
>>    187            reboot_entry = fncpy(reboot_code_buffer,
> Can you please try the patch below:
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 963b5284d284..f86b3d17928e 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -571,7 +571,7 @@ static inline void section_update(unsigned long addr, pmdval_t mask,
>   {
>   	pmd_t *pmd;
>   
> -	pmd = pmd_off_k(addr);
> +	pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, addr), addr), addr), addr);
>   
>   #ifdef CONFIG_ARM_LPAE
>   	pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot);
This fixes kexec issue! Thanks!


Feel free to add:

Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Fixes: 218f1c390557 ("arm: add support for folded p4d page tables")
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland