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From: Chao Fan <fanc.fnst@cn.fujitsu.com>
To: Dave Young <dyoung@redhat.com>
Cc: "bhe@redhat.com" <bhe@redhat.com>,
	Junichi Nomura <j-nomura@ce.jp.nec.com>,
	Borislav Petkov <bp@alien8.de>,
	"kasong@redhat.com" <kasong@redhat.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel
Date: Thu, 4 Apr 2019 15:20:07 +0800
Message-ID: <20190404072007.GL1555@localhost.localdomain> (raw)
In-Reply-To: <20190404064130.GA5530@dhcp-128-65.nay.redhat.com>

On Thu, Apr 04, 2019 at 02:41:30PM +0800, Dave Young wrote:
>On 04/04/19 at 11:22am, Dave Young wrote:
>> On 04/04/19 at 11:10am, Baoquan He wrote:
>> > On 04/04/19 at 11:00am, Baoquan He wrote:
>> > > On 04/04/19 at 10:52am, Dave Young wrote:
>> > > > On 04/04/19 at 01:23am, Junichi Nomura wrote:
>> >  +	/* Save RSDP address for later use. */
>> >  +	boot_params->acpi_rsdp_addr = get_rsdp_addr();
>> >  +
>> >  +	error("Hang kernel for kexec debugging");
>> > 
>> > Sorry, here I means calling error() to hang kernel after calling
>> > get_rsdp_addr().
>> 
>> Thanks, it did not hang, it always reset to firmware/grub boot menu.
>> I'm pretty sure now the bug exists in get_rsdp_addr().
>
>static acpi_physical_address kexec_get_rsdp_addr(void)
>{
>...
>        /* Get systab from boot params. */
>        systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
>        if (!systab)
>              error("EFI system table not found in kexec boot_params.");
> 
>...
>  -> add error("hang me") here will have a hang
>...
>        return __efi_get_rsdp_addr((unsigned long)esd->tables,
>                                   systab->nr_tables, true);
> 

I have an idea, but not sure whether is a problem.
In code of Nomura:

#if defined(CONFIG_EFI) && defined(CONFIG_X86_64)
[...]
        if (strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
                debug_putstr("Wrong kexec EFI loader signature.\n");
                return 0;
        }

        /* Get systab from boot params. */
        systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
[...]
#endif

After review agian, I wonder what will happen if 32bit-efi boot 64bit
OS.

Ever meet a problem:
https://lkml.org/lkml/2019/2/8/845

It's a efi32 bootloader to boot a 64bit OS, then a problem happened.


Thanks,
Chao Fan

>But add error("hang me") in __efi_get_rsdp_addr it did not hang.
> 
>It seems reference the systab pointer cause a system reset.
> 
>A question is does the identity mapping covered the memory address of
>systab?
> 
>In my case it is 0xdad9ef18
> 
>If the memory is mapped on demand, then there will be problems, it
>should cover setup_data and efi table space.
> 
>Thanks
>Dave
>
>
>



  reply index

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-22 11:03 [PATCH] x86/boot: Use EFI setup data if provided Junichi Nomura
2019-03-22 15:23 ` Borislav Petkov
2019-03-25  0:27   ` Junichi Nomura
2019-03-25  6:01     ` Dave Young
2019-03-25  6:19       ` Dave Young
2019-03-25  6:45         ` Kairui Song
2019-03-25  6:47         ` Junichi Nomura
2019-03-25  6:59           ` Dave Young
2019-03-25  8:27             ` [PATCH v2] " Junichi Nomura
2019-03-25  8:54               ` Boris Petkov
2019-03-25  9:25                 ` [PATCH v2] x86/boot: Don't try to search RSDP from EFI when kexec-booted Junichi Nomura
2019-03-25 10:15                 ` [PATCH v2] x86/boot: Use EFI setup data if provided Dave Young
2019-03-25 10:36                   ` Junichi Nomura
2019-03-25 11:16                     ` Dave Young
2019-03-25 12:01                     ` Borislav Petkov
2019-03-25 12:23                       ` Dave Young
2019-03-25 12:32                         ` Borislav Petkov
2019-03-25 23:10                           ` Junichi Nomura
2019-03-26 12:46                             ` Dave Young
2019-03-26 13:57                             ` Borislav Petkov
2019-03-27  1:48                               ` bhe
2019-03-27 12:14                                 ` Borislav Petkov
2019-03-28  4:17                                 ` Junichi Nomura
2019-03-28  6:26                                   ` Chao Fan
2019-03-28  6:43                                   ` bhe
2019-03-28  7:43                                     ` Junichi Nomura
2019-03-28 15:52                                       ` Borislav Petkov
2019-03-29  3:05                                         ` Junichi Nomura
2019-03-29  8:39                                           ` Borislav Petkov
2019-03-29  9:05                                             ` Chao Fan
2019-03-29  9:16                                               ` Borislav Petkov
2019-03-29  9:37                                                 ` Junichi Nomura
2019-03-29  9:44                                                   ` Chao Fan
2019-03-29  9:56                                                     ` Junichi Nomura
2019-03-29  7:20                                         ` [PATCH] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel Junichi Nomura
2019-03-29  7:49                                           ` bhe
2019-03-29  8:29                                           ` Chao Fan
2019-03-29  8:39                                             ` Junichi Nomura
2019-03-29  9:18                                               ` Chao Fan
2019-03-29  9:16                                             ` bhe
2019-03-29  9:20                                               ` Chao Fan
2019-04-01  0:08                                         ` [PATCH v2] " Junichi Nomura
2019-04-02  9:41                                           ` Chao Fan
2019-04-02  9:53                                             ` Junichi Nomura
2019-04-02 11:06                                               ` Chao Fan
2019-04-02 10:22                                                 ` Junichi Nomura
2019-04-02 12:03                                           ` Dave Young
2019-04-03  5:35                                             ` Chao Fan
2019-04-03  5:53                                               ` Dave Young
2019-04-03  6:39                                                 ` Dave Young
2019-04-03  7:30                                                   ` Chao Fan
2019-04-03  7:50                                                     ` bhe
2019-04-03  8:23                                                       ` Dave Young
2019-04-03  8:26                                                         ` Dave Young
2019-04-03 16:14                                                           ` Borislav Petkov
2019-04-04  1:02                                                             ` Chao Fan
2019-04-03  9:28                                                       ` Chao Fan
2019-04-03  7:21                                                 ` Chao Fan
2019-04-03  8:09                                                   ` Dave Young
2019-04-03  8:23                                                     ` Chao Fan
2019-04-03  9:02                                                       ` Chao Fan
2019-04-03  9:39                                                         ` Chao Fan
2019-04-04  1:23                                                         ` Junichi Nomura
2019-04-04  2:52                                                           ` Dave Young
2019-04-04  3:00                                                             ` bhe
2019-04-04  3:10                                                               ` bhe
2019-04-04  3:22                                                                 ` Dave Young
2019-04-04  6:41                                                                   ` Dave Young
2019-04-04  7:20                                                                     ` Chao Fan [this message]
2019-04-04  7:41                                                                       ` Dave Young
2019-04-04  7:48                                                                         ` Chao Fan
2019-04-04 12:22                                                                         ` Borislav Petkov
2019-04-04 14:08                                                                           ` Dave Young
2019-04-03  8:18                                                   ` Dave Young
2019-04-02 10:25                                         ` [PATCH v3] " Junichi Nomura
2019-04-04  7:32                                           ` Dave Young
2019-04-04 12:24                                             ` Borislav Petkov
2019-04-04 14:12                                               ` Dave Young
2019-04-04 14:41                                                 ` Borislav Petkov
2019-04-05  1:36                                                   ` Dave Young
2019-04-05  4:19                                             ` Junichi Nomura
2019-03-28 23:11                                       ` [PATCH v2] x86/boot: Use EFI setup data if provided bhe
2019-03-29  3:34                                         ` Junichi Nomura
2019-03-29  3:52                                           ` bhe
2019-03-29  5:16                                             ` Junichi Nomura
2019-03-25  7:27   ` [PATCH] " Baoquan He
2019-03-25  7:53     ` Borislav Petkov
2019-03-25  8:21       ` Baoquan He
2019-03-25  8:43         ` Thomas Gleixner
2019-03-25  9:03           ` Baoquan He

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