From: Denys Vlasenko <dvlasenk@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andy Lutomirski <luto@amacapital.net>, Oleg Nesterov <oleg@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 2/3 RESEND] x86, acpi: On S3 failure, just fall through
Date: Fri,  3 Jul 2015 22:08:34 +0200
Message-Id: <1435954115-1800-2-git-send-email-dvlasenk@redhat.com>
In-Reply-To: <1435954115-1800-1-git-send-email-dvlasenk@redhat.com>
References: <1435954115-1800-1-git-send-email-dvlasenk@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2138
Lines: 60

Th "jmp" deleted by this patch in fact compiles to "jmp to next insn",
since ".p2align 4,,7" happens to not do any alignment -
aligning to 2^4 would require more than 7 bytes of padding:

000000b0 <do_suspend_lowlevel>:
  b0:   e8 fc ff ff ff          call   <save_processor_state>
  b5:   e8 8d ff ff ff          call   47 <save_registers>
  ba:   6a 03                   push   $0x3
  bc:   e8 fc ff ff ff          call   <x86_acpi_enter_sleep_state>
  c1:   83 c4 04                add    $0x4,%esp
  c4:   eb 00                   jmp    c6 <ret_point>   <============ THIS
000000c6 <ret_point>:
  c6:   e8 c4 ff ff ff          call   8f <restore_registers>

Run-tested.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Pavel Machek <pavel@ucw.cz>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ingo Molnar <mingo@kernel.org>
CC: Borislav Petkov <bp@alien8.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Alexei Starovoitov <ast@plumgrid.com>
CC: Will Drewry <wad@chromium.org>
CC: Kees Cook <keescook@chromium.org>
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
---
 arch/x86/kernel/acpi/wakeup_32.S | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/x86/kernel/acpi/wakeup_32.S b/arch/x86/kernel/acpi/wakeup_32.S
index eef2bd3..5fec9b0 100644
--- a/arch/x86/kernel/acpi/wakeup_32.S
+++ b/arch/x86/kernel/acpi/wakeup_32.S
@@ -68,11 +68,8 @@ ENTRY(do_suspend_lowlevel)
 	pushl	$3
 	call	x86_acpi_enter_sleep_state
 	addl	$4, %esp
+# If S3 fails, we simply fall through to S3 wakeup code:
 
-#	In case of S3 failure, we'll emerge here.  Jump
-# 	to ret_point to recover
-	jmp	ret_point
-	.p2align 4,,7
 ret_point:
 	call	restore_registers
 	call	restore_processor_state
-- 
1.8.1.4

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