On Mon, Jul 24, 2023 at 4:48 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@nec.com> wrote:
From: Kazuhito Hagio <k-hagio-ab@nec.com>

As written in the previous patch, some recent kernels do not have the
".rodata" symbol.  As a result, the get_linux_banner_from_vmlinux()
returns FALSE and the slower fallback routine is used.

Use "__start_rodata" symbol if the ".rodata" symbol is not available.

Reported-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
---
Note that I chose to use ".rodata" first to not change the current
stable behavior for old vmcores, in this case.

 kernel.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel.c b/kernel.c
index 9801812387bd..2114700eecc8 100644
--- a/kernel.c
+++ b/kernel.c
@@ -11891,8 +11891,13 @@ 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");
@@ -11905,7 +11910,7 @@ 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") - start_rodata;

        if (!bfd_get_section_contents(st->bfd,
                                      sect,

Looks good to me. So: Ack.

Thanks
Lianbo
 
--
2.31.1