A set of unwinder and tooling fixes:
- Ensure that the stack pointer on x86 is aligned again so that the
unwinder does not read past the end of the stack
- Discard .note.gnu.property section which has a pointlessly different
alignment than the other note sections. That confuses tooling of all
sorts including readelf, libbpf and pahole.
x86/show_trace_log_lvl: Ensure stack pointer is aligned, again
The commit e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned")
tried to align the stack pointer in show_trace_log_lvl(), otherwise the
"stack < stack_info.end" check can't guarantee that the last read does
not go past the end of the stack.
However, we have the same problem with the initial value of the stack
pointer, it can also be unaligned. So without this patch this trivial
kernel module
#include <linux/module.h>
static int init(void)
{
asm volatile("sub $0x4,%rsp");
dump_stack();
asm volatile("add $0x4,%rsp");
return -EAGAIN;
}
module_init(init);
MODULE_LICENSE("GPL");
crashes the kernel.
Fixes: e335bb51cc15 ("x86/unwind: Ensure stack pointer is aligned")
Signed-off-by: Vernon Lovejoy <vlovejoy@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20230512104232.GA10227@redhat.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
1 file changed
