Commit e27e5bea authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Paolo Bonzini

x86/ibt, objtool: Add IBT_NOSEAL()

Add a macro which prevents a function from getting sealed if there are
no compile-time references to it.
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Message-Id: <20220818213927.e44fmxkoq4yj6ybn@treble>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 20ec3ebd
......@@ -31,6 +31,16 @@
#define __noendbr __attribute__((nocf_check))
/*
* Create a dummy function pointer reference to prevent objtool from marking
* the function as needing to be "sealed" (i.e. ENDBR converted to NOP by
* apply_ibt_endbr()).
*/
#define IBT_NOSEAL(fname) \
".pushsection .discard.ibt_endbr_noseal\n\t" \
_ASM_PTR fname "\n\t" \
".popsection\n\t"
static inline __attribute_const__ u32 gen_endbr(void)
{
u32 endbr;
......@@ -84,6 +94,7 @@ extern __noendbr void ibt_restore(u64 save);
#ifndef __ASSEMBLY__
#define ASM_ENDBR
#define IBT_NOSEAL(name)
#define __noendbr
......
......@@ -4096,7 +4096,8 @@ static int validate_ibt(struct objtool_file *file)
* These sections can reference text addresses, but not with
* the intent to indirect branch to them.
*/
if (!strncmp(sec->name, ".discard", 8) ||
if ((!strncmp(sec->name, ".discard", 8) &&
strcmp(sec->name, ".discard.ibt_endbr_noseal")) ||
!strncmp(sec->name, ".debug", 6) ||
!strcmp(sec->name, ".altinstructions") ||
!strcmp(sec->name, ".ibt_endbr_seal") ||
......
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