linux-kernel - [PATCH v6 22/25] x86/asm: annotate indirect jumps

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Message-Id: <20201013003203.4168817-23-samitolvanen@google.com>
Date:   Mon, 12 Oct 2020 17:32:00 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com,
        kernel-hardening@...ts.openwall.com, linux-arch@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        x86@...nel.org, Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v6 22/25] x86/asm: annotate indirect jumps

Running objtool --vmlinux --duplicate on vmlinux.o produces a few
warnings about indirect jumps with retpoline:

  vmlinux.o: warning: objtool: wakeup_long64()+0x61: indirect jump
  found in RETPOLINE build
  ...

This change adds ANNOTATE_RETPOLINE_SAFE annotations to the jumps
in assembly code to stop the warnings.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 arch/x86/kernel/acpi/wakeup_64.S  | 2 ++
 arch/x86/platform/pvh/head.S      | 2 ++
 arch/x86/power/hibernate_asm_64.S | 3 +++
 3 files changed, 7 insertions(+)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index c8daa92f38dc..041e79c4e195 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -7,6 +7,7 @@
 #include <asm/msr.h>
 #include <asm/asm-offsets.h>
 #include <asm/frame.h>
+#include <asm/nospec-branch.h>
 
 # Copyright 2003 Pavel Machek <pavel@...e.cz
 
@@ -39,6 +40,7 @@ SYM_FUNC_START(wakeup_long64)
 	movq	saved_rbp, %rbp
 
 	movq	saved_rip, %rax
+	ANNOTATE_RETPOLINE_SAFE
 	jmp	*%rax
 SYM_FUNC_END(wakeup_long64)
 
diff --git a/arch/x86/platform/pvh/head.S b/arch/x86/platform/pvh/head.S
index 43b4d864817e..640b79cc64b8 100644
--- a/arch/x86/platform/pvh/head.S
+++ b/arch/x86/platform/pvh/head.S
@@ -15,6 +15,7 @@
 #include <asm/asm.h>
 #include <asm/boot.h>
 #include <asm/processor-flags.h>
+#include <asm/nospec-branch.h>
 #include <asm/msr.h>
 #include <xen/interface/elfnote.h>
 
@@ -105,6 +106,7 @@ SYM_CODE_START_LOCAL(pvh_start_xen)
 	/* startup_64 expects boot_params in %rsi. */
 	mov $_pa(pvh_bootparams), %rsi
 	mov $_pa(startup_64), %rax
+	ANNOTATE_RETPOLINE_SAFE
 	jmp *%rax
 
 #else /* CONFIG_X86_64 */
diff --git a/arch/x86/power/hibernate_asm_64.S b/arch/x86/power/hibernate_asm_64.S
index 7918b8415f13..715509d94fa3 100644
--- a/arch/x86/power/hibernate_asm_64.S
+++ b/arch/x86/power/hibernate_asm_64.S
@@ -21,6 +21,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/processor-flags.h>
 #include <asm/frame.h>
+#include <asm/nospec-branch.h>
 
 SYM_FUNC_START(swsusp_arch_suspend)
 	movq	$saved_context, %rax
@@ -66,6 +67,7 @@ SYM_CODE_START(restore_image)
 
 	/* jump to relocated restore code */
 	movq	relocated_restore_code(%rip), %rcx
+	ANNOTATE_RETPOLINE_SAFE
 	jmpq	*%rcx
 SYM_CODE_END(restore_image)
 
@@ -97,6 +99,7 @@ SYM_CODE_START(core_restore_code)
 
 .Ldone:
 	/* jump to the restore_registers address from the image header */
+	ANNOTATE_RETPOLINE_SAFE
 	jmpq	*%r8
 SYM_CODE_END(core_restore_code)
 
-- 
2.28.0.1011.ga647a8990f-goog