Re: [Crash-utility] [PATCH] arm64: Use VA_BITS for page_offset calculation

On Wed, Oct 27, 2021 at 11:17 AM HAGIO KAZUHITO(萩尾　一仁) <k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com> > wrote: Hi Pingfan, Lianbo, -----Original Message----- > On Mon, Oct 25, 2021 at 4:43 PM HAGIO KAZUHITO(萩尾　一仁) > <k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com> > wrote: > > > > Hi, > > > > Here is a patch for the issue reported by Ankur. > > Could you help test this with your ramdumps and arm64 machines? > > > The patch looks good to me. And I will schedule a machine to have a test. Pingfan, thank you for the check and test, it's very helpful. Ankur told me that the patch was working fine. Lianbo, my understanding is that to get a raw ramdump, hardware functionality I mean that the raw dumpfile had been generated on my machine, but it didn't reproduce this issue. :-)

I guess that may be related to the kernel '.config'. or something is required. But maybe you can reproduce a similar situation with QEMU memory dump without vmcoreinfo? e.g. on RHEL: # virsh dump <domain> domain.dump --memory-only Thank you for the suggestion, Kazu. but you may need a kernel configured with VA_BITS=48 to reproduce and check the fix, I guess. I can confirm that kernel has enabled the VA_BITS=48 as below: CONFIG_ARM64_VA_BITS_48=y CONFIG_ARM64_VA_BITS=48 Thanks. Thanks, Kazu > > Regards, > Pingfan > > -- > > From 028ddf655c847c16cce23198017d2ff0169bb4de Mon Sep 17 00:00:00 2001 > > From: Kazuhito Hagio <k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com> > > > Date: Mon, 25 Oct 2021 16:53:26 +0900 > > Subject: [PATCH] arm64: Use VA_BITS for page_offset calculation > > > > Commit 167d37e347fe ("arm64: assign page_offset with VA_BITS kernel > > configuration value") changed the page_offset calculation from > > using VA_BITS_ACTUAL to CONFIG_ARM64_VA_BITS. This caused an error > > for ramdumps without vmcoreinfo like this: > > > > crash: vmlinux and /var/tmp/ramdump_elf_XUtCMT do not match! > > > > Set the vmcoreinfo value to VA_BITS if available, and use VA_BITS > > for page_offset calculation instead. > > > > Also remove ARM64_FLIP_PAGE_OFFSET_ACTUAL because it's not used > > actually. > > > > Reported-by: Ankur Bansal <er.ankurbansal(a)gmail.com <mailto:er.ankurbansal@gmail.com> > > > Signed-off-by: Kazuhito Hagio <k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com> > > > --- > > arm64.c | 5 ++++- > > defs.h | 4 +--- > > 2 files changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/arm64.c b/arm64.c > > index 7069312671cf..3dcbcc642fda 100644 > > --- a/arm64.c > > +++ b/arm64.c > > @@ -404,7 +404,7 @@ arm64_init(int when) > > fprintf(fp, "CONFIG_ARM64_VA_BITS: %ld\n", ms->CONFIG_ARM64_VA_BITS); > > fprintf(fp, " VA_BITS_ACTUAL: %ld\n", ms->VA_BITS_ACTUAL); > > fprintf(fp, "(calculated) VA_BITS: %ld\n", ms->VA_BITS); > > - fprintf(fp, " PAGE_OFFSET: %lx\n", ARM64_FLIP_PAGE_OFFSET_ACTUAL); > > + fprintf(fp, " PAGE_OFFSET: %lx\n", ARM64_FLIP_PAGE_OFFSET); > > fprintf(fp, " VA_START: %lx\n", ms->VA_START); > > fprintf(fp, " modules: %lx - %lx\n", ms->modules_vaddr, > ms->modules_end); > > fprintf(fp, " vmalloc: %lx - %lx\n", ms->vmalloc_start_addr, > ms->vmalloc_end); > > @@ -4031,6 +4031,9 @@ arm64_calc_VA_BITS(void) > > error(FATAL, "cannot determine VA_BITS_ACTUAL\n"); > > } > > > > + if (machdep->machspec->CONFIG_ARM64_VA_BITS) > > + machdep->machspec->VA_BITS = machdep->machspec->CONFIG_ARM64_VA_BITS; > > + > > /* > > * The mm flip commit is introduced before 52-bits VA, which is before the > > * commit to export NUMBER(TCR_EL1_T1SZ) > > diff --git a/defs.h b/defs.h > > index 8b356d5e8959..971005596506 100644 > > --- a/defs.h > > +++ b/defs.h > > @@ -3238,9 +3238,7 @@ typedef signed int s32; > > #define ARM64_PAGE_OFFSET ((0xffffffffffffffffUL) \ > > << (machdep->machspec->VA_BITS - 1)) > > /* kernels >= v5.4 the kernel VA space is flipped */ > > -#define ARM64_FLIP_PAGE_OFFSET (-(1UL) << machdep->machspec->CONFIG_ARM64_VA_BITS) > > -#define ARM64_FLIP_PAGE_OFFSET_ACTUAL ((0xffffffffffffffffUL) \ > > - - ((1UL) << machdep->machspec->VA_BITS_ACTUAL) + 1) > > +#define ARM64_FLIP_PAGE_OFFSET (-(1UL) << machdep->machspec->VA_BITS) > > > > #define ARM64_USERSPACE_TOP ((1UL) << machdep->machspec->VA_BITS) > > #define ARM64_USERSPACE_TOP_ACTUAL ((1UL) << machdep->machspec->VA_BITS_ACTUAL) > > -- > > 2.27.0 > >