linux-kernel - Re: [PATCH 02/24] x86/traps: Move arch/x86/kernel/traps.c to arch/x86/entry/

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Message-ID: <YTDS/p/bnsTFzNES@hirez.programming.kicks-ass.net>
Date:   Thu, 2 Sep 2021 15:34:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Lai Jiangshan <laijs@...ux.alibaba.com>
Cc:     Joerg Roedel <jroedel@...e.de>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Chester Lin <clin@...e.com>, Juergen Gross <jgross@...e.com>,
        andrew.cooper3@...rix.com, ndesaulniers@...gle.com
Subject: Re: [PATCH 02/24] x86/traps: Move arch/x86/kernel/traps.c to
 arch/x86/entry/

On Thu, Sep 02, 2021 at 02:05:41PM +0200, Peter Zijlstra wrote:
> On Thu, Sep 02, 2021 at 07:54:25PM +0800, Lai Jiangshan wrote:
> > For example, stack-protector is instrumenting many noninstr functions now
> > if the CONFIG is yes.  It is normally Ok and gcc is adding per-function control
> > on it.
> 
> IIRC the latest compiler have an attribute for this too, that really
> should be added to noinstr. Lemme go find.

Something like so... Nick ?

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 49b0ac8b6fd3..6a15c3d8df5c 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -62,6 +62,12 @@
 #define __no_sanitize_coverage
 #endif
 
+#if defined(CONFIG_STACKPROTECTOR)
+#define __no_stack_protector __attribute__((no_stack_protector))
+#else
+#define __no_stack_protector
+#endif
+
 /*
  * Not all versions of clang implement the type-generic versions
  * of the builtin overflow checkers. Fortunately, clang implements
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index cb9217fc60af..7ac0a3f11ba9 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -128,6 +128,12 @@
 #define __no_sanitize_coverage
 #endif
 
+#if defined(CONFIG_STACKPROTECTOR) && __has_attribute__(__no_stack_protector__)
+#define __no_stack_protector __attribute__((no_stack_protector))
+#else
+#define __no_stack_protector
+#endif
+
 #if GCC_VERSION >= 50100
 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
 #endif
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index e4ea86fc584d..5ae1c08dba8d 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -210,7 +210,8 @@ struct ftrace_likely_data {
 /* Section for code which can't be instrumented at all */
 #define noinstr								\
 	noinline notrace __attribute((__section__(".noinstr.text")))	\
-	__no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage
+	__no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage \
+	__no_stack_protector
 
 #endif /* __KERNEL__ */