[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20200618144801.760070502@infradead.org>
Date: Thu, 18 Jun 2020 16:44:10 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, dvyukov@...gle.com,
elver@...gle.com, andreyknvl@...gle.com, mark.rutland@....com,
mhelsley@...are.com, rostedt@...dmis.org, jthierry@...hat.com,
mbenes@...e.cz, peterz@...radead.org
Subject: [PATCH 3/7] x86/entry: Fixup bad_iret vs noinstr
vmlinux.o: warning: objtool: fixup_bad_iret()+0x8e: call to memcpy() leaves .noinstr.text section
Worse, when KASAN there is no telling what memcpy() actually is. Force
the use of __memcpy() which is our assmebly implementation.
Reported-by: Marco Elver <elver@...gle.com>
Suggested-by: Marco Elver <elver@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/x86/kernel/traps.c | 6 +++---
arch/x86/lib/memcpy_64.S | 4 ++++
2 files changed, 7 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -685,13 +685,13 @@ struct bad_iret_stack *fixup_bad_iret(st
(struct bad_iret_stack *)__this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1;
/* Copy the IRET target to the temporary storage. */
- memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
+ __memcpy(&tmp.regs.ip, (void *)s->regs.sp, 5*8);
/* Copy the remainder of the stack from the current stack. */
- memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
+ __memcpy(&tmp, s, offsetof(struct bad_iret_stack, regs.ip));
/* Update the entry stack */
- memcpy(new_stack, &tmp, sizeof(tmp));
+ __memcpy(new_stack, &tmp, sizeof(tmp));
BUG_ON(!user_mode(&new_stack->regs));
return new_stack;
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -8,6 +8,8 @@
#include <asm/alternative-asm.h>
#include <asm/export.h>
+.pushsection .noinstr.text, "ax"
+
/*
* We build a jump to memcpy_orig by default which gets NOPped out on
* the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which
@@ -184,6 +186,8 @@ SYM_FUNC_START_LOCAL(memcpy_orig)
retq
SYM_FUNC_END(memcpy_orig)
+.popsection
+
#ifndef CONFIG_UML
MCSAFE_TEST_CTL
Powered by blists - more mailing lists