Hello Kazu,
I think we can try to generalize the kaslr offset extraction.
I won't speak for other architectures, but for s390 that
get_kaslr_offset_arm64()
should work fine. The only concern of mine is this TODO statement:
if (_text <= vaddr && vaddr <= _end) {
DEBUG_MSG("info->kaslr_offset: %lx\n", info->kaslr_offset);
return info->kaslr_offset;
} else {
/*
* TODO: we need to check if it is vmalloc/vmmemmap/module
* address, we will have different offset
*/
return 0;
}
Could you explain this one?
Thanks,
Mikhail
On 09.12.2019 23:02, Kazuhito Hagio wrote:
> Hi Mikhail,
>
> Sorry for late reply.
>
>> -----Original Message-----
>> Since kernel v5.2 KASLR is supported on s390. In makedumpfile however no
>> support has been added yet. This patch adds the arch specific function
>> get_kaslr_offset() for s390x.
>> Since the values in vmcoreinfo are already relocated, the patch is
>> mainly relevant for vmlinux processing (-x option).
>
> In the current implementation of makedumpfile, the get_kaslr_offset(vaddr)
> is supposed to return the KASLR offset only when the offset is needed to
> add to the vaddr. So generally symbols from kernel (vmlinux) need it, but
> symbols from modules are resolved dynamically and don't need the offset.
\>
> This patch always returns the offset if any, as a result, I guess this patch
> will not work as expected with module symbols in filter config file.
>
> So... How about making get_kaslr_offset_arm64() general for other archs
> (get_kaslr_offset_general() or something), then using it also for s390?
> If OK, I can do that generalization.
>
> Thanks,
> Kazu
>
>>
>> Signed-off-by: Philipp Rudo <[email protected]>
>> Signed-off-by: Mikhail Zaslonko <[email protected]>
>> ---
>> arch/s390x.c | 32 ++++++++++++++++++++++++++++++++
>> makedumpfile.h | 3 ++-
>> 2 files changed, 34 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390x.c b/arch/s390x.c
>> index bf9d58e..892df14 100644
>> --- a/arch/s390x.c
>> +++ b/arch/s390x.c
>> @@ -122,6 +122,38 @@ get_machdep_info_s390x(void)
>> return TRUE;
>> }
>>
>> +unsigned long
>> +get_kaslr_offset_s390x(unsigned long vaddr)
>> +{
>> + unsigned int i;
>> + char buf[BUFSIZE_FGETS], *endp;
>> +
>> + if (!info->file_vmcoreinfo)
>> + return FALSE;
>> +
>> + if (fseek(info->file_vmcoreinfo, 0, SEEK_SET) < 0) {
>> + ERRMSG("Can't seek the vmcoreinfo file(%s). %s\n",
>> + info->name_vmcoreinfo, strerror(errno));
>> + return FALSE;
>> + }
>> +
>> + while (fgets(buf, BUFSIZE_FGETS, info->file_vmcoreinfo)) {
>> + i = strlen(buf);
>> + if (!i)
>> + break;
>> + if (buf[i - 1] == '\n')
>> + buf[i - 1] = '\0';
>> + if (strncmp(buf, STR_KERNELOFFSET,
>> + strlen(STR_KERNELOFFSET)) == 0) {
>> + info->kaslr_offset =
>> + strtoul(buf + strlen(STR_KERNELOFFSET), &endp,
>> 16);
>> + DEBUG_MSG("info->kaslr_offset: %lx\n",
>> info->kaslr_offset);
>> + }
>> + }
>> +
>> + return info->kaslr_offset;
>> +}
>> +
>> static int
>> is_vmalloc_addr_s390x(unsigned long vaddr)
>> {
>> diff --git a/makedumpfile.h b/makedumpfile.h
>> index ac11e90..26f6247 100644
>> --- a/makedumpfile.h
>> +++ b/makedumpfile.h
>> @@ -1071,11 +1071,12 @@ unsigned long long vaddr_to_paddr_ppc(unsigned long
>> vaddr);
>> int get_machdep_info_s390x(void);
>> unsigned long long vaddr_to_paddr_s390x(unsigned long vaddr);
>> int is_iomem_phys_addr_s390x(unsigned long addr);
>> +unsigned long get_kaslr_offset_s390x(unsigned long vaddr);
>> #define find_vmemmap() stub_false()
>> #define get_phys_base() stub_true()
>> #define get_machdep_info() get_machdep_info_s390x()
>> #define get_versiondep_info() stub_true()
>> -#define get_kaslr_offset(X) stub_false()
>> +#define get_kaslr_offset(X) get_kaslr_offset_s390x(X)
>> #define vaddr_to_paddr(X) vaddr_to_paddr_s390x(X)
>> #define paddr_to_vaddr(X) paddr_to_vaddr_general(X)
>> #define is_phys_addr(X) is_iomem_phys_addr_s390x(X)
>> --
>> 2.17.1
>>
>
>
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