[PATCH v2] LoongArch: Load vmlinux.efi to the link address
Huacai Chen
chenhuacai at kernel.org
Tue Nov 28 20:15:17 PST 2023
Hi, all,
On Tue, Nov 28, 2023 at 2:27 PM WANG Rui <wangrui at loongson.cn> wrote:
>
> Hi,
>
> On Mon, Nov 27, 2023 at 10:36 AM RuiRui Yang <ruyang at redhat.com> wrote:
> >
> > On Mon, 27 Nov 2023 at 09:53, RuiRui Yang <ruyang at redhat.com> wrote:
> > >
> > > On Sat, 25 Nov 2023 at 14:54, WANG Rui <wangrui at loongson.cn> wrote:
> > > >
> > > > Currently, kexec loads vmlinux.efi to address 0 instead of the link
> > > > address. This causes kexec to fail to boot the new vmlinux.efi on qemu.
> > > >
> > > > pei_loongarch_load: kernel_segment: 0000000000000000
> > > > pei_loongarch_load: kernel_entry: 00000000013f1000
> > > > pei_loongarch_load: image_size: 0000000001ca0000
> > > > pei_loongarch_load: text_offset: 0000000000200000
> > > > pei_loongarch_load: phys_offset: 0000000000000000
> > > > pei_loongarch_load: PE format: yes
> > > > loongarch_load_other_segments:333: command_line: kexec console=ttyS0,115200
> > > > kexec_load: entry = 0x13f1000 flags = 0x1020000
> > > > nr_segments = 2
> > > > segment[0].buf = 0x7fffeea38010
> > > > segment[0].bufsz = 0x1b55200
> > > > segment[0].mem = (nil)
> > > > segment[0].memsz = 0x1ca0000
> > > > segment[1].buf = 0x5555570940b0
> > > > segment[1].bufsz = 0x200
> > > > segment[1].mem = 0x1ca0000
> > > > segment[1].memsz = 0x4000
> > > >
> > > > This patch constrains the range of the kernel segment by `hole_min`
> > > > and `hole_max` to place vmlinux.efi exactly at the link address.
> > > >
> > > > pei_loongarch_load: kernel_segment: 0000000000200000
> > > > pei_loongarch_load: kernel_entry: 00000000013f1000
> > > > pei_loongarch_load: image_size: 0000000001ca0000
> > > > pei_loongarch_load: text_offset: 0000000000200000
> > > > pei_loongarch_load: phys_offset: 0000000000000000
> > > > pei_loongarch_load: PE format: yes
> > > > loongarch_load_other_segments:339: command_line: kexec console=ttyS0,115200
> > > > kexec_load: entry = 0x13f1000 flags = 0x1020000
> > > > nr_segments = 2
> > > > segment[0].buf = 0x7ffff2028010
> > > > segment[0].bufsz = 0x1b55200
> > > > segment[0].mem = 0x200000
> > > > segment[0].memsz = 0x1ca0000
> > > > segment[1].buf = 0x555557498098
> > > > segment[1].bufsz = 0x200
> > > > segment[1].mem = 0x1ea0000
> > > > segment[1].memsz = 0x4000
> > > >
> > > > Signed-off-by: WANG Rui <wangrui at loongson.cn>
> > > > ---
> > > >
> > > > v1->v2:
> > > > * Fix the issue preventing it from working on the physical machine.
> > > >
> > > > kexec/arch/loongarch/kexec-loongarch.c | 10 +++++++---
> > > > 1 file changed, 7 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/kexec/arch/loongarch/kexec-loongarch.c b/kexec/arch/loongarch/kexec-loongarch.c
> > > > index 62ff8fd..32a42d2 100644
> > > > --- a/kexec/arch/loongarch/kexec-loongarch.c
> > > > +++ b/kexec/arch/loongarch/kexec-loongarch.c
> > > > @@ -265,9 +265,13 @@ unsigned long loongarch_locate_kernel_segment(struct kexec_info *info)
> > > > hole = ULONG_MAX;
> > > > }
> > > > } else {
> > > > - hole = locate_hole(info,
> > > > - loongarch_mem.text_offset + loongarch_mem.image_size,
> > > > - MiB(1), 0, ULONG_MAX, 1);
> > > > + unsigned long hole_min;
> > > > + unsigned long hole_max;
> > > > +
> > > > + hole_min = loongarch_mem.text_offset;
> > > > + hole_max = hole_min + loongarch_mem.image_size;
> > > > + hole = locate_hole(info, loongarch_mem.image_size,
> > > > + MiB(1), hole_min, hole_max, 1);
> > > >
> > > > if (hole == ULONG_MAX)
> > > > dbgprintf("%s: locate_hole failed\n", __func__);
> > >
> > > Hi,
> > >
> > > Previously when I played with the zboot kernel on a kvm guest I
> > > noticed this issue, but I found that the 1st 2M memory is memblock
> > > reserved but it is not shown in /proc/iomem as reserved, I suspect the
> > > 1st 2M is not usable for some arch specific reason but I was not sure.
> > > Below patch can fix it but due to my rusty knowledge of loongarch I
> >
> > Correct about my English wording a bit, I meant about rusty knowledge
> > of kexec details and newbish loongarch knowledge,
> > BTW, the webmail often randomly choose the sender email, I usually use
> > another email for community, that is Dave Young <dyoung at redhat.com>,
> > same person ;)
> >
> > Anyway, since this is loongarch specific, it would be better to leave
> > you guys the arch people to see how to fix it better.
> >
> > > did not send it out. I suspect even if the locate_hole avoids the
> > > wrong memory, in the 2nd kernel it could still access it. Correct?
>
> I can confirm that the mapping of the 1st 2M in iomem on qemu causes
> kexec to not work. The root cause is that LoongArch's vmlinux.efi can
> only run on the link address, which is why I limit the allocation
> location of the kernel segment through hole min/max, not the kernel's
> iomem.
>
> Hucai, what do you think about the 1st 2M mapping type in the kernel?
I agree with WANG Rui, this should be fixed in kexec-tools, and
'nomap' is not for such a usage.
Huacai
>
> > >
> > > Index: linux/arch/loongarch/kernel/mem.c
> > > ===================================================================
> > > --- linux.orig/arch/loongarch/kernel/mem.c 2023-06-02
> > > 10:24:09.633593320 +0800
> > > +++ linux/arch/loongarch/kernel/mem.c 2023-10-05 15:27:05.609455460 +0800
> > > @@ -52,8 +52,8 @@
> > > memblock_set_current_limit(PFN_PHYS(max_low_pfn));
> > > memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
> > >
> > > - /* Reserve the first 2MB */
> > > - memblock_reserve(PHYS_OFFSET, 0x200000);
> > > + /* Mark the first 2MB as nomap */
> > > + memblock_mark_nomap(PHYS_OFFSET, 0x200000);
> > >
> > > /* Reserve the kernel text/data/bss */
> > > memblock_reserve(__pa_symbol(&_text),
> > >
> > >
> > > > --
> > > > 2.42.0
> > > >
> > > >
> > > > _______________________________________________
> > > > kexec mailing list
> > > > kexec at lists.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/kexec
> > > >
> >
>
>
> --
> WANG Rui
>
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