From f4e343b6559eda19efe972b9dcd52e479320e388 Mon Sep 17 00:00:00 2001 From: Peter Xu Date: Thu, 12 Dec 2024 15:48:00 -0500 Subject: [PATCH] scripts/qemu-gdb: Simplify fs_base fetching for coroutines There're a bunch of code trying to fetch fs_base in different ways. IIUC the simplest way instead is "$fs_base". It also has the benefit that it'll work for both live gdb session or coredumps. Signed-off-by: Peter Xu Message-ID: <20241212204801.1420528-3-peterx@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- scripts/qemugdb/coroutine.py | 23 ++--------------------- 1 file changed, 2 insertions(+), 21 deletions(-) diff --git a/scripts/qemugdb/coroutine.py b/scripts/qemugdb/coroutine.py index 7db46d4b68..20f76ed37b 100644 --- a/scripts/qemugdb/coroutine.py +++ b/scripts/qemugdb/coroutine.py @@ -13,28 +13,9 @@ import gdb VOID_PTR = gdb.lookup_type('void').pointer() -def get_fs_base(): - '''Fetch %fs base value using arch_prctl(ARCH_GET_FS). This is - pthread_self().''' - # %rsp - 120 is scratch space according to the SystemV ABI - old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') - gdb.execute('call (int)arch_prctl(0x1003, $rsp - 120)', False, True) - fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') - gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True) - return fs_base - def pthread_self(): - '''Fetch pthread_self() from the glibc start_thread function.''' - f = gdb.newest_frame() - while f.name() != 'start_thread': - f = f.older() - if f is None: - return get_fs_base() - - try: - return f.read_var("arg") - except ValueError: - return get_fs_base() + '''Fetch the base address of TLS.''' + return gdb.parse_and_eval("$fs_base") def get_glibc_pointer_guard(): '''Fetch glibc pointer guard value''' -- 2.30.2