Messages in this thread | | | Date | Fri, 25 Nov 2022 14:06:40 +0100 | From | Peter Zijlstra <> | Subject | Re: [Question] About UNWIND_HINT_ENTRY on entry_SYSCALL_64. |
| |
On Fri, Nov 25, 2022 at 07:41:46PM +0900, Yun Levi wrote: > Hello. > > While I try to see the information related to ORC in vmlinux, > I'm trying to find out ORC information related to entry_SYSCALL_64's address. > > For this, I've tried to take the following step: > 1. booting the kernel with the "nokaslr" option. > 2. Getting ORC information by "objdump orc dump vmlinux" > 3. cat /proc/kallsyms and check the address of "entry_SYSCALL_64" > - In my kernel, It's address .text + a00000 > 4. Find out related ORC entry gotten in step 2. > > But, I couldn't find the reason why entry_SYSCALL_64's orc info isn't > encoded with end =1. > Instead, It was encoded as INVALID ORC entry like: > > .text+a00000: sp:(und) bp:(und) type:call end:0 > > IIUC, Some of the code is started with UNWIND_HINT_ENTRY or UNWIND_HINT_EMPTY, > it should be encoded with end = 1. But it doesn't. > > Am I wrong?
$ readelf -Ws defconfig-build/vmlinux.o | grep entry_SYSCALL_64 178466: 0000000000000029 0 NOTYPE GLOBAL DEFAULT 18 entry_SYSCALL_64_safe_stack 188596: 0000000000000000 422 NOTYPE GLOBAL DEFAULT 18 entry_SYSCALL_64 210374: 0000000000000038 0 NOTYPE GLOBAL DEFAULT 18 entry_SYSCALL_64_after_hwframe
$ readelf -WS defconfig-build/vmlinux.o | grep "\[18\]" [18] .entry.text PROGBITS 0000000000000000 e59f00 001838 00 AX 0 0 64
$ tools/objtool/objtool --dump=orc defconfig-build/vmlinux.o | grep ".entry.text+0" .entry.text+0: sp:(und) bp:(und) type:call end:1
| |