[Crash-utility] [PATCH] Disable DT_DEBUG lookup by GDB inside the vmcore

Crash with GDB 16.2, the following warnings are printed: crash> crash: page excluded: kernel virtual address: c0000000022d6098 type: "gdb_readmem_callback" crash: page excluded: kernel virtual address: c0000000022d6098 type: "gdb_readmem_callback" This occurs because the elf_locate_base function in GDB 16.2 attempts to read the address of the dynamic linker runtime structure, which is present in the .dynamic section of the executable. However, this section may be excluded from the dump by makedumpfile. Commit e906eaca2b1a ("Fix the issue of "page excluded" messages flooding") attempted fix this by suppressing these warnings for regular users, but the warnings still appear when crash is started in debug mode. To fix this, remove the elf_locate_base call in GDB that tries to read the .dynamic section, as this information is not useful for debugging kernel images in either dump or live kernel scenarios. Cc: Sourabh Jain <sourabhjain(a)linux.ibm.com&gt; Cc: Lianbo Jiang <lijiang(a)redhat.com&gt; Signed-off-by: Shivang Upadhyay <shivangu(a)linux.ibm.com&gt; --- gdb-16.2.patch | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/gdb-16.2.patch b/gdb-16.2.patch index 151e4e2..7b79cdf 100644 --- a/gdb-16.2.patch +++ b/gdb-16.2.patch @@ -1952,3 +1952,19 @@ exit 0 } /* Remember the bfd indexes for the .text, .data, .bss and +--- gdb-16.2/gdb/solib-svr4.c.orig ++++ gdb-16.2/gdb/solib-svr4.c +@@ -742,11 +742,13 @@ elf_locate_base (void) + return extract_typed_address (pbuf, ptr_type); + } + ++#ifndef CRASH_MERGE + /* Find DT_DEBUG. */ + if (gdb_bfd_scan_elf_dyntag (DT_DEBUG, current_program_space->exec_bfd (), + &dyn_ptr, NULL) + || scan_dyntag_auxv (DT_DEBUG, &dyn_ptr, NULL)) + return dyn_ptr; ++#endif + + /* This may be a static executable. Look for the symbol + conventionally named _r_debug, as a last resort. */ -- 2.49.0