On Mon, Jul 24, 2023 at 3:07 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio...@nec.com>
wrote:
> On 2023/07/24 15:51, lijiang wrote:
> > How about reading out the linux_banner string to a buffer with readmem()?
>
> No, this is a version check for the namelist (vmlinux).
>
>
Ah, you are right, Kazu.
>> If the vmlinux does not have only the ".rodata" symbol, is it possible
> >> to use "__start_rodata" symbol or something? i.e. is there no symbol
> >> that has the same address as .rodata section?
> >>
> >>
> > I tried the "__start_rodata" symbol, but it does not work.
>
> How did you try? There is no "__start_rodata" symbol?
>
> I mean something like this:
>
> --- a/kernel.c
> +++ b/kernel.c
> @@ -11893,8 +11893,13 @@ int get_linux_banner_from_vmlinux(char *buf,
> size_t size)
> {
> struct bfd_section *sect;
> long offset;
> + ulong start_rodata;
>
> - if (!kernel_symbol_exists(".rodata"))
> + if (kernel_symbol_exists(".rodata"))
> + start_rodata = symbol_value(".rodata");
> + else if (kernel_symbol_exists("__start_rodata"))
> + start_rodata = symbol_value("__start_rodata");
> + else
> return FALSE;
>
> sect = bfd_get_section_by_name(st->bfd, ".rodata");
>
The ".rodata" is a section, I mistakenly replaced the ".rodata" with the
symbol "__start_rodata" in a debug patch, so it does not work. :-)
diff --git a/kernel.c b/kernel.c
index 546eed9..3c50fa4 100644
--- a/kernel.c
+++ b/kernel.c
@@ -11894,7 +11894,7 @@ int get_linux_banner_from_vmlinux(char *buf, size_t
size)
struct bfd_section *sect;
long offset;
- if (!kernel_symbol_exists(".rodata"))
+ if (!kernel_symbol_exists("__start_rodata"))
return FALSE;
sect = bfd_get_section_by_name(st->bfd, ".rodata");
@@ -11907,7 +11907,7 @@ int get_linux_banner_from_vmlinux(char *buf, size_t
size)
* value in vmlinux file, but relative offset to linux_banner
* object in .rodata section is idential.
*/
- offset = symbol_value("linux_banner") - symbol_value(".rodata");
+ offset = symbol_value("linux_banner") -
symbol_value("__start_rodata");
if (!bfd_get_section_contents(st->bfd,
sect,
@@ -11916,5 +11916,6 @@ int get_linux_banner_from_vmlinux(char *buf, size_t
size)
size))
return FALSE;
+ error(INFO, "%s\n", buf);
return TRUE;
For now, the get_linux_banner_from_vmlinux() works again with the debug
patch.
Thanks.
Lianbo
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