On Wed, Jan 19, 2022 at 12:33:02AM +0100, Borislav Petkov wrote: > On Tue, Jan 18, 2022 at 03:01:20PM -0800, Josh Poimboeuf wrote: > > With the two WARN_ONs in media_request_object_complete(), GCC apparently > > considers the two reachable() asm statements as duplicates, and it > > removes the second one. > > Could that be the same thing: > > net/xfrm/xfrm_output.o: warning: objtool: xfrm_output_resume()+0x2e0: unreachable instruction > > I see two WARN_ONs in asm output there too... If one of the '__bug_table' asm snippets isn't immediately followed by the .L[un]reachable asm, then yeah, it's the same issue. For example it's supposed to look something like this: # 472 "net/xfrm/xfrm_output.c" 1 1: .byte 0x0f, 0x0b .pushsection __bug_table,"aw" 2: .long 1b - 2b # bug_entry::bug_addr .long .LC4 - 2b # bug_entry::file # .word 472 # bug_entry::line # .word 2307 # bug_entry::flags # .org 2b+12 # .popsection # 0 "" 2 # 472 "net/xfrm/xfrm_output.c" 1 .Lreachable1666: .pushsection .discard.reachable .long .Lreachable1666 - . .popsection NOT just this: # 472 "net/xfrm/xfrm_output.c" 1 1: .byte 0x0f, 0x0b .pushsection __bug_table,"aw" 2: .long 1b - 2b # bug_entry::bug_addr .long .LC4 - 2b # bug_entry::file # .word 472 # bug_entry::line # .word 2307 # bug_entry::flags # .org 2b+12 # .popsection # some other code here... There's a bunch of those throughout the code base. The current annotate_[un]reachable() implementations are carefully written to avoid that happening. -- Josh
