linux-kernel - [RFC][PATCH 3/6] x86/callthunk: No callthunk for restore_processor

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Message-ID: <20230112143825.704223863@infradead.org>
Date:   Thu, 12 Jan 2023 15:31:44 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, Joan Bruguera <joanbrugueram@...il.com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        Juergen Gross <jgross@...e.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        Jan Beulich <jbeulich@...e.com>,
        Roger Pau Monne <roger.pau@...rix.com>,
        Kees Cook <keescook@...omium.org>, mark.rutland@....com
Subject: [RFC][PATCH 3/6] x86/callthunk: No callthunk for restore_processor_state()

From: Joan Bruguera <joanbrugueram@...il.com>

When resuming from suspend we don't have coherent CPU state, trying to
do callthunks here isn't going to work. Specifically GS isn't set yet.

Signed-off-by: Joan Bruguera <joanbrugueram@...il.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20230109040531.7888-1-joanbrugueram@gmail.com
---
 arch/x86/kernel/callthunks.c |    5 +++++
 arch/x86/power/cpu.c         |    3 +++
 2 files changed, 8 insertions(+)

--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -7,6 +7,7 @@
 #include <linux/memory.h>
 #include <linux/moduleloader.h>
 #include <linux/static_call.h>
+#include <linux/suspend.h>
 
 #include <asm/alternative.h>
 #include <asm/asm-offsets.h>
@@ -151,6 +152,10 @@ static bool skip_addr(void *dest)
 	    dest < (void*)hypercall_page + PAGE_SIZE)
 		return true;
 #endif
+#ifdef CONFIG_PM_SLEEP
+	if (dest == restore_processor_state)
+		return true;
+#endif
 	return false;
 }