Re: [Crash-utility] [PATCH] x86_64: Fix that Particular kvaddr is converted to wrong paddr (RHEL6 x86_64)

> But because it is such a fundamental change that you are proposing, it might > make sense to create a check/macro that is specific to the vsyscall region. What is check/macro? How do we check what? Certainly, these addresses are vsyscall region. After applying this patch, crash looks read vsyscall region correctly.

crash> sym vsyscall // abbreviation // ffffffffff600000 (t) .vsyscall_0 ffffffffff600140 (t) .vsyscall_fn ffffffffff600180 (d) .vsyscall_gtod_data ffffffffff600180 (D) __vsyscall_gtod_data ffffffffff600400 (t) .vsyscall_1 ffffffffff600800 (t) .vsyscall_2 ffffffffff700680 (A) VDSO64_vsyscall_gtod_data crash> sym VDSO symbol not found: VDSO possible alternatives: ffffffffff700000 (A) VDSO64_PRELINK ffffffffff700670 (A) VDSO64_jiffies ffffffffff700678 (A) VDSO64_vgetcpu_mode ffffffffff700680 (A) VDSO64_vsyscall_gtod_data //////// not patched ///////// crash> dis .vsyscall_0 0xffffffffff600000 <.vsyscall_0>: add %al,(%rax) 0xffffffffff600002 <vgettimeofday+2>: add %al,(%rax) 0xffffffffff600004 <vgettimeofday+4>: add %al,(%rax) 0xffffffffff600006 <vgettimeofday+6>: add %al,(%rax) 0xffffffffff600008 <vgettimeofday+8>: add %al,(%rax) 0xffffffffff60000a <vgettimeofday+10>: add %al,(%rax) // abbreviation // //////// after applying this patch ///////// crash> dis .vsyscall_0 0xffffffffff600000 <.vsyscall_0>: push %rbp 0xffffffffff600001 <vgettimeofday+1>: mov %rsp,%rbp 0xffffffffff600004 <vgettimeofday+4>: push %r13 0xffffffffff600006 <vgettimeofday+6>: push %r12 0xffffffffff600008 <vgettimeofday+8>: mov %rdi,%r12 0xffffffffff60000b <vgettimeofday+11>: push %rbx 0xffffffffff60000c <vgettimeofday+12>: mov %rsi,%rbx 0xffffffffff60000f <vgettimeofday+15>: sub $0x8,%rsp 0xffffffffff600013 <vgettimeofday+19>: test %rdi,%rdi 0xffffffffff600016 <vgettimeofday+22>: je 0xffffffffff6000d5 <vgettimeofday+213> // abbreviation // On 2015/12/22 22:42, Dave Anderson wrote: > > > ----- Original Message ----- >> I didn't check XEN HYPER MODE, I don't have XEN. >> If we need similar statement "if (kvaddr < MODULES_END)" >> please add inside in "if (XEN_HYPER_MODE())" (1859@x86_64_kvtop) >> >> >> >> >> >From ed300b74998e0923313e4fd14b9a41e305942b44 Mon Sep 17 00:00:00 2001 >> From: Nakajima Akira <nakajima.akira(a)nttcom.co.jp&gt; >> Date: Tue, 22 Dec 2015 15:46:42 +0900 >> Subject: [PATCH] Fix that particular kvaddr is converted to wrong paddr >> >> BUG INFO >> Particular kvaddr is converted to wrong paddr. >> You can see this bug on RHEL6_x86_64. (at present only RHEL6) >> (I checked RHEL5, RHEL7, Fedora21, Fedora23) > > > I am out of the office until January 4th (only checking email until then), > and will not > be able to look into this until then. But because it is such a fundamental > change that > you are proposing, it might make sense to create a check/macro that is > specific to > the vsyscall region. > > Thanks, > Dave > >> >> from /proc/kallsyms >> ffffffffff6008c0 D __jiffies >> >> /////////// wrong /////////// >> crash> vtop ffffffffff6008c0 >> VIRTUAL PHYSICAL >> ffffffffff6008c0 7f6008c0 >> >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >> ffffea00000623b8 1c11000 0 0 1 20000000000400 >> reserved >> >> >> crash> rd ffffffffff6008c0 >> ffffffffff6008c0: 0000000000000000 ........ >> >> >> /////////// correct /////////// >> crash> vtop ffffffffff6008c0 >> VIRTUAL PHYSICAL >> ffffffffff6008c0 1c118c0 >> >> PAGE PHYSICAL MAPPING INDEX CNT FLAGS >> ffffea00000623b8 1c11000 0 0 1 20000000000400 >> reserved >> >> >> crash> rd ffffffffff6008c0 >> ffffffffff6008c0: 00000000ffffe43a :....... >> >> Reported-by: Nakajima Akira <nakajima.akira(a)nttcom.co.jp&gt; >> Signed-off-by: Nakajima Akira <nakajima.akira(a)nttcom.co.jp&gt; >> >> --- >> x86_64.c | 28 +++++++++++++++------------- >> 1 files changed, 15 insertions(+), 13 deletions(-) >> >> diff --git a/x86_64.c b/x86_64.c >> index ff6fdd5..dab4d43 100644 >> --- a/x86_64.c >> +++ b/x86_64.c >> @@ -1872,19 +1872,21 @@ x86_64_kvtop(struct task_context *tc, ulong >> kvaddr, >> physaddr_t *paddr, int verbo >> fprintf(fp, "PAGE DIRECTORY: %lx\n", *pml4); >> } >> } else { >> - if (!vt->vmalloc_start) { >> - *paddr = x86_64_VTOP(kvaddr); >> - return TRUE; >> - } >> - >> - if (!IS_VMALLOC_ADDR(kvaddr)) { >> - *paddr = x86_64_VTOP(kvaddr); >> - if (!verbose) >> - return TRUE; >> - } >> - >> - if (XEN() && (kt->xen_flags & WRITABLE_PAGE_TABLES)) >> - return (x86_64_kvtop_xen_wpt(tc, kvaddr, paddr, verbose)); >> + if (kvaddr < MODULES_END) { >> + if (!vt->vmalloc_start) { >> + *paddr = x86_64_VTOP(kvaddr); >> + return TRUE; >> + } >> + >> + if (!IS_VMALLOC_ADDR(kvaddr)) { >> + *paddr = x86_64_VTOP(kvaddr); >> + if (!verbose) >> + return TRUE; >> + } >> + >> + if (XEN() && (kt->xen_flags & WRITABLE_PAGE_TABLES)) >> + return (x86_64_kvtop_xen_wpt(tc, kvaddr, paddr, verbose)); >> + } >> >> /* >> * pgd = pgd_offset_k(addr); >> -- >> 1.7.1 >> >> >> -- >> Crash-utility mailing list >> Crash-utility(a)redhat.com >> https://www.redhat.com/mailman/listinfo/crash-utility > > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility > . > -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility