On Tue, Nov 10, 2020 at 10:59:55AM -0800, Sami Tolvanen wrote: > On Tue, Nov 10, 2020 at 9:46 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > On Mon, Nov 09, 2020 at 08:29:24PM -0600, Josh Poimboeuf wrote: > > > On Mon, Nov 09, 2020 at 03:11:41PM -0800, Sami Tolvanen wrote: > > > > CONFIG_XEN > > > > > > > > __switch_to_asm()+0x0: undefined stack state > > > > xen_hypercall_set_trap_table()+0x0: <=== (sym) > > > > With your branch + GCC 9 I can recreate all the warnings except this > > one. > > In a gcc build this warning is replaced with a different one: > > vmlinux.o: warning: objtool: __startup_secondary_64()+0x7: return with > modified stack frame > > This just seems to depend on which function is placed right after the > code in xen-head.S. With gcc, the disassembly looks like this: > > 0000000000000000 <asm_cpu_bringup_and_idle>: > 0: e8 00 00 00 00 callq 5 <asm_cpu_bringup_and_idle+0x5> > 1: R_X86_64_PLT32 cpu_bringup_and_idle-0x4 > 5: e9 f6 0f 00 00 jmpq 1000 > <xen_hypercall_set_trap_table> > ... > 0000000000001000 <xen_hypercall_set_trap_table>: > ... > ... > 0000000000002000 <__startup_secondary_64>: > > With Clang+LTO, we end up with __switch_to_asm here instead of > __startup_secondary_64. I still don't see this warning for some reason. Is it fixed by adding cpu_bringup_and_idle() to global_noreturns[] in tools/objtool/check.c? -- Josh
