On 7/19/2018 1:43 AM, Bhupesh Sharma wrote:
> The existing methodology to obtain 'info->page_offset' from reading
> _stext symbol (from kallsyms) doesn't work well in KASLR boot cases on
> arm64 machines as the PAGE_OFFSET (or the virtual address which
> indicates the start of the linear region) can be randomized as well
> on basis of the kaslr-seed.
>
> Since the value of PAGE_OFFSET inside the kernel is randomized in such
> cases and there is no existing mechanism of conveying this value from
> kernel-space to user-space, so we can use the method used by archs like
> x86_64 to generate the 'info->page_offset' value from the PT_LOAD
> segments by subtracting the phy_addr from virt_addr of a PT_LOAD
> segment.
>
> This approach works fine both with KASLR and non-KASLR boot cases.
>
> I tested this on my qualcomm-amberwing board. Here are some logs from
> the KASLR boot cases:
>
> - Verify that the EFI firmware supports 'kaslr-seed':
>
> chosen {
> kaslr-seed = <0x0 0x0>;
> <..snip..>
> };
>
> - Verify that '--mem-usage' works well after this fix as well (I used
> kernel 4.18.0-rc4+ for my checks):
>
> The kernel version is not supported.
> The makedumpfile operation may be incomplete.
>
> TYPE PAGES EXCLUDABLE DESCRIPTION
> ----------------------------------------------------------------------
> ZERO 4396 yes Pages filled
> with zero
> NON_PRI_CACHE 27859 yes Cache pages
> without private flag
> PRI_CACHE 18490 yes Cache pages with
> private flag
> USER 2728 yes User process
> pages
> FREE 1465848 yes Free pages
> KERN_DATA 18537 no Dumpable kernel
> data
>
> page size: 65536
> Total pages on system: 1537858
> Total size on system: 100785061888 Byte
>
> Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx>
> ---
> arch/arm64.c | 23 ++++++++++++++++++-----
> common.h | 1 +
> makedumpfile.h | 1 +
> 3 files changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64.c b/arch/arm64.c
> index 2fd3e1874376..9e8c77c76935 100644
> --- a/arch/arm64.c
> +++ b/arch/arm64.c
> @@ -265,6 +265,9 @@ get_xen_info_arm64(void)
> int
> get_versiondep_info_arm64(void)
> {
> + int i;
> + unsigned long long phys_start;
> + unsigned long long virt_start;
> ulong _stext;
>
> _stext = get_stext_symbol();
> @@ -289,12 +292,22 @@ get_versiondep_info_arm64(void)
> return FALSE;
> }
>
> - info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
> -
> - DEBUG_MSG("page_offset=%lx, va_bits=%d\n", info->page_offset,
> - va_bits);
According to makedumpfile commit 4944f93484 ("x86_64: Calculate page_offset
in case of re-filtering/sadump/virsh dump"), in case of re-filtering,
we don't have any PT_LOAD. So, with this patch, we cannot re-filter
dump file on arm64 system?
If we cannot, is it better to leave the above behind the following
pt_load section for re-filtering non-KASLR dump?
> + if (get_num_pt_loads()) {
> + for (i = 0;
> + get_pt_load(i, &phys_start, NULL, &virt_start, NULL);
> + i++) {
> + if (virt_start != NOT_KV_ADDR
> + && virt_start < __START_KERNEL_map
> + && phys_start != NOT_PADDR && phys_start != NOT_PADDR_ARM64) {
> + info->page_offset = virt_start - phys_start;
> + DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n",
> + info->page_offset, va_bits);
> + return TRUE;
> + }
> + }
> + }
I'll adjust some indents for readability.
>
> - return TRUE;
> + return FALSE;
> }
>
> /*
> diff --git a/common.h b/common.h
> index 6e2f657a79c7..a8181777dbb7 100644
> --- a/common.h
> +++ b/common.h
> @@ -48,6 +48,7 @@
> #define NOT_MEMMAP_ADDR (0x0)
> #define NOT_KV_ADDR (0x0)
> #define NOT_PADDR (ULONGLONG_MAX)
> +#define NOT_PADDR_ARM64 (0x0000000010a80000UL)
I think that this should not be in common.h, because it's not for
arch-specific definitions, so I'll move it to makedumpfile.h.
> #define BADADDR ((ulong)(-1))
>
> #endif /* COMMON_H */
> diff --git a/makedumpfile.h b/makedumpfile.h
> index 5ff94b8e4ac6..5297279f0f3b 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -2020,6 +2020,7 @@ struct domain_list {
> #define MFNS_PER_FRAME (info->page_size / sizeof(unsigned long))
>
> #ifdef __aarch64__
> +#define __START_KERNEL_map (0xffffffff80000000UL)
This #ifdef here is for the definitions related to Xen extraction.
I'll move it to the same place as the above.
> unsigned long long kvtop_xen_arm64(unsigned long kvaddr);
> #define kvtop_xen(X) kvtop_xen_arm64(X)
> #endif /* aarch64 */
>
I attached a patch that was applied my suggestions.
How about it?
Thanks,
Kazu
diff --git a/arch/arm64.c b/arch/arm64.c
index 2fd3e18..836ce17 100644
--- a/arch/arm64.c
+++ b/arch/arm64.c
@@ -265,6 +265,9 @@ get_xen_info_arm64(void)
int
get_versiondep_info_arm64(void)
{
+ int i;
+ unsigned long long phys_start;
+ unsigned long long virt_start;
ulong _stext;
_stext = get_stext_symbol();
@@ -289,8 +292,23 @@ get_versiondep_info_arm64(void)
return FALSE;
}
- info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
+ if (get_num_pt_loads()) {
+ for (i = 0;
+ get_pt_load(i, &phys_start, NULL, &virt_start, NULL);
+ i++) {
+ if (virt_start != NOT_KV_ADDR
+ && virt_start < __START_KERNEL_map
+ && phys_start != NOT_PADDR
+ && phys_start != NOT_PADDR_ARM64) {
+ info->page_offset = virt_start - phys_start;
+ DEBUG_MSG("info->page_offset: %lx, VA_BITS: %d\n",
+ info->page_offset, va_bits);
+ return TRUE;
+ }
+ }
+ }
+ info->page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
DEBUG_MSG("page_offset=%lx, va_bits=%d\n", info->page_offset,
va_bits);
diff --git a/makedumpfile.h b/makedumpfile.h
index 5ff94b8..ba85f03 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -542,6 +542,10 @@ do { \
#ifdef __aarch64__
unsigned long get_kvbase_arm64(void);
#define KVBASE get_kvbase_arm64()
+
+#define __START_KERNEL_map (0xffffffff80000000UL)
+#define NOT_PADDR_ARM64 (0x0000000010a80000UL)
+
#endif /* aarch64 */
#ifdef __arm__
--
1.8.3.1
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