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    SubjectRe: [PATCH v2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel
    On Wed, Apr 03, 2019 at 05:02:11PM +0800, Chao Fan wrote:
    >On Wed, Apr 03, 2019 at 04:23:06PM +0800, Chao Fan wrote:
    >>On Wed, Apr 03, 2019 at 04:09:16PM +0800, Dave Young wrote:
    >>>On 04/03/19 at 03:21pm, Chao Fan wrote:
    >>>> On Wed, Apr 03, 2019 at 01:53:40PM +0800, Dave Young wrote:
    >>>> >On 04/03/19 at 01:35pm, Chao Fan wrote:
    >>>> >> On Tue, Apr 02, 2019 at 08:03:19PM +0800, Dave Young wrote:
    >>>> >> >On 04/01/19 at 12:08am, Junichi Nomura wrote:
    >[...]
    >>>> >
    >>>> >It is weird to me. Probably I need find out why I can not reproduce the
    >>>> >bug this patch is addressing first.
    >>>>
    >>>> Hmm, is your laptop booted from EFI or legacy BIOS?
    >>>
    >>>EFI booted.
    >>>
    >>>> >
    >>>> >earlyprintk seems not working for me anymore, it is not easy to debug on
    >>>> >laptop now.
    >>>>
    >>>> Another computer can help print the console message.
    >>>> I remeber you are good at debug on two computers.
    >>>
    >>>I used to use earlyprintk, but seems earlyprintk can not work so early.
    >>>So I only can try to comment out code manually.
    >>
    >>Ah, I got it. If you want to use earlyprintk to print message of
    >>get_rsdp_addr(), you should change some code.
    >>Because get_rsdp_addr() is called before earlyprintk initialed.
    >>
    >>I am still testing, but in my debug stage, I change like this:
    >>diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
    >>index c0d6c560df69..dbbe8d9a5792 100644
    >>--- a/arch/x86/boot/compressed/misc.c
    >>+++ b/arch/x86/boot/compressed/misc.c
    >>@@ -352,7 +352,6 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
    >> boot_params->hdr.loadflags &= ~KASLR_FLAG;
    >>
    >> /* Save RSDP address for later use. */
    >>- boot_params->acpi_rsdp_addr = get_rsdp_addr();
    >>
    >> sanitize_boot_params(boot_params);
    >>
    >>@@ -368,6 +367,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
    >> cols = boot_params->screen_info.orig_video_cols;
    >>
    >> console_init();
    >>+ boot_params->acpi_rsdp_addr = get_rsdp_addr();
    >> debug_putstr("early console in extract_kernel\n");
    >>
    >> free_mem_ptr = heap; /* Heap */
    >>
    >>Call this function after console_init().
    >>That will make earlyprintk works.
    >>
    >>>
    >>>It seems to be still some bug in early acpi code because if I
    >>>return 0 in get rsdp function it just works.
    >>>
    >>>This guess make sense to me for now:
    >>>1. nokaslr does not work because it may only avoid randomization, but it
    >>>does not avoid running the early acpi parsing code.
    >>>
    >>>2. kexec does not work without the patch we talked about, because I just
    >>>reproduced Junichi reported bug, sometimes hang, or reset, it is
    >>>understandable.
    >>>
    >>>3. kexec does not work with the patch, so there is still bugs in the
    >>>code.
    >>>
    >>>So several things to do is:
    >>>
    >>>Fix 1. (separate issue), Baoquan or either of you may want to fix it :)
    >>
    >>For 1, I think it's not needed to fix. Since not only KASLR needs RSDP.
    >>So nokaslr should not stop the acpi parsing code.
    >>>
    >>>Fix 3. need more debugging, have you or Junichi run tests on more real
    >>>hardware, maybe it is easier to reproduce on real hardware, I'm glad to
    >>>help to try test patch or provide any help.
    >>
    >>I am still testing in real hardware.
    >
    >Hi Dave,
    >
    >I find a Fujitsu Desktop PC to test it.
    >Without this PATCH, it failed to kexec and kdump.
    >With this PATCH, it succeed to kexec.
    >But failed to kdump. From the log, I think it didn't jump to the second
    >kernel, just reboot after panic. I have not figured out what's the
    >problem, but it seems not caused by this PATCH.

    I comment out this line:
    diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
    index c0d6c560df69..4d826abe659c 100644
    --- a/arch/x86/boot/compressed/misc.c
    +++ b/arch/x86/boot/compressed/misc.c
    @@ -352,7 +352,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
    boot_params->hdr.loadflags &= ~KASLR_FLAG;

    /* Save RSDP address for later use. */
    - boot_params->acpi_rsdp_addr = get_rsdp_addr();
    + //boot_params->acpi_rsdp_addr = get_rsdp_addr();

    sanitize_boot_params(boot_params);

    Kdump also failed to jump to the second kernel and just hang.
    So I think it's another issue. As for this PATCH, I think it works.
    So for now, we only find your laptop will meet the problem, so maybe
    you can debug for more information.
    Thanks,
    Chao Fan

    >So I still think this PATCH works for the Fujitsu Desktop PC.
    >
    >As for your issue, I think there may be some problems related to specified
    >hardware. Are you using a Lenovo laptop?
    >
    >And I am not sure how Nomura tested it.
    >
    >Thanks,
    >Chao Fan
    >
    >>
    >>Thanks,
    >>Chao Fan
    >>
    >>>
    >>>Thanks
    >>>Dave
    >>>
    >>>


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