[Qemu-devel] [PATCH 1/1] dump: Update correct kdump phys_base field for AArch64

[Qemu-devel] [PATCH 1/1] dump: Update correct kdump phys_base field for AArch64

[Wei Huang]

For guest kernel that supports KASLR, the load address can change every
time when guest VM runs. To find the physical base address correctly,
current QEMU dump searches VMCOREINFO for the string "NUMBER(phys_base)=".
However this string pattern is only available on x86_64. AArch64 uses a
different field, called "NUMBER(PHYS_OFFSET)=". This patch makes sure
QEMU dump uses the correct string on AArch64.

Signed-off-by: Wei Huang <wei@redhat.com>
---
 dump.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/dump.c b/dump.c
index 097e60b..6bdb0db 100644
--- a/dump.c
+++ b/dump.c
@@ -1609,10 +1609,18 @@ static void vmcoreinfo_update_phys_base(DumpState *s)
 
     lines = g_strsplit((char *)vmci, "\n", -1);
     for (i = 0; lines[i]; i++) {
-        if (g_str_has_prefix(lines[i], "NUMBER(phys_base)=")) {
-            if (qemu_strtou64(lines[i] + 18, NULL, 16,
+        const char *prefix = NULL;
+
+        if (s->dump_info.d_machine == EM_X86_64) {
+            prefix = "NUMBER(phys_base)=";
+        } else if (s->dump_info.d_machine == EM_AARCH64) {
+            prefix = "NUMBER(PHYS_OFFSET)=";
+        }
+
+        if (prefix && g_str_has_prefix(lines[i], prefix)) {
+            if (qemu_strtou64(lines[i] + strlen(prefix), NULL, 16,
                               &phys_base) < 0) {
-                warn_report("Failed to read NUMBER(phys_base)=");
+                warn_report("Failed to read %s", prefix);
             } else {
                 s->dump_info.phys_base = phys_base;
             }
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH 1/1] dump: Update correct kdump phys_base field for AArch64

[Marc-André Lureau]

Hi

On Fri, Mar 9, 2018 at 6:03 PM, Wei Huang <wei@redhat.com> wrote:
> For guest kernel that supports KASLR, the load address can change every
> time when guest VM runs. To find the physical base address correctly,
> current QEMU dump searches VMCOREINFO for the string "NUMBER(phys_base)=".
> However this string pattern is only available on x86_64. AArch64 uses a
> different field, called "NUMBER(PHYS_OFFSET)=". This patch makes sure
> QEMU dump uses the correct string on AArch64.
>
> Signed-off-by: Wei Huang <wei@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


> ---
>  dump.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/dump.c b/dump.c
> index 097e60b..6bdb0db 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -1609,10 +1609,18 @@ static void vmcoreinfo_update_phys_base(DumpState *s)
>
>      lines = g_strsplit((char *)vmci, "\n", -1);
>      for (i = 0; lines[i]; i++) {
> -        if (g_str_has_prefix(lines[i], "NUMBER(phys_base)=")) {
> -            if (qemu_strtou64(lines[i] + 18, NULL, 16,
> +        const char *prefix = NULL;
> +
> +        if (s->dump_info.d_machine == EM_X86_64) {
> +            prefix = "NUMBER(phys_base)=";
> +        } else if (s->dump_info.d_machine == EM_AARCH64) {
> +            prefix = "NUMBER(PHYS_OFFSET)=";
> +        }
> +
> +        if (prefix && g_str_has_prefix(lines[i], prefix)) {
> +            if (qemu_strtou64(lines[i] + strlen(prefix), NULL, 16,
>                                &phys_base) < 0) {
> -                warn_report("Failed to read NUMBER(phys_base)=");
> +                warn_report("Failed to read %s", prefix);
>              } else {
>                  s->dump_info.phys_base = phys_base;
>              }
> --
> 1.8.3.1
>

Re: [Qemu-devel] [PATCH 1/1] dump: Update correct kdump phys_base field for AArch64

[Peter Maydell]

On 11 March 2018 at 17:42, Marc-André Lureau
<marcandre.lureau@redhat.com> wrote:
> Hi
>
> On Fri, Mar 9, 2018 at 6:03 PM, Wei Huang <wei@redhat.com> wrote:
>> For guest kernel that supports KASLR, the load address can change every
>> time when guest VM runs. To find the physical base address correctly,
>> current QEMU dump searches VMCOREINFO for the string "NUMBER(phys_base)=".
>> However this string pattern is only available on x86_64. AArch64 uses a
>> different field, called "NUMBER(PHYS_OFFSET)=". This patch makes sure
>> QEMU dump uses the correct string on AArch64.
>>
>> Signed-off-by: Wei Huang <wei@redhat.com>
>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Thanks; applied to target-arm.next for 2.12.

-- PMM