Re: mmotm 2018-05-10-16-34 uploaded (objtool)

[Josh Poimboeuf]

On Thu, May 10, 2018 at 06:06:38PM -0700, Randy Dunlap wrote:
> >> Hi Josh, Peter:
> >>
> >> Is this something that you already have fixes for?
> >>
> >>
> >> on x86_64:
> >>
> >> drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame
> >> drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame
> > 
> > I don't recall seeing that one.  Can you share the .config and/or .o
> > file?
> > 
> 
> Sure.  Both are attached.

Here's a fix (applies on top of the GCC 8 patches I posted this week):

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 9bb04fddd3c8..a358489a1560 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -961,11 +961,15 @@ static struct rela *find_switch_table(struct objtool_file *file,
 		if (find_symbol_containing(file->rodata, text_rela->addend))
 			continue;
 
+		/* mov [rodata addr], %reg */
 		rodata_rela = find_rela_by_dest(file->rodata, text_rela->addend);
-		if (!rodata_rela)
-			continue;
+		if (rodata_rela)
+			return rodata_rela;
 
-		return rodata_rela;
+		/* mov [rodata_addr](%rip), %reg */
+		rodata_rela = find_rela_by_dest(file->rodata, text_rela->addend + 4);
+		if (rodata_rela)
+			return rodata_rela;
 	}
 
 	return NULL;