> 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@xxxxxxxxxxxx>
>> 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@xxxxxxxxxxxx>
>> Signed-off-by: Nakajima Akira <nakajima.akira@xxxxxxxxxxxx>
>>
>> ---
>> 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
>>
>>
>> --
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>
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