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From: Guenter Roeck <linux@roeck-us.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	"James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	linux-alpha@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org,
	netdev@vger.kernel.org, linux-sparse@vger.kernel.org,
	Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 1/4] compiler.h: Introduce absolute_pointer macro
Date: Sun, 12 Sep 2021 09:01:46 -0700	[thread overview]
Message-ID: <20210912160149.2227137-2-linux@roeck-us.net> (raw)
In-Reply-To: <20210912160149.2227137-1-linux@roeck-us.net>

absolute_pointer() disassociates a pointer from its originating symbol
type and context. Use it to prevent compiler warnings/errors such as

drivers/net/ethernet/i825xx/82596.c: In function 'i82596_probe':
./arch/m68k/include/asm/string.h:72:25: error:
	'__builtin_memcpy' reading 6 bytes from a region of size 0
		[-Werror=stringop-overread]

Such warnings may be reported by gcc 11.x for string and memory operations
on fixed addresses.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 include/linux/compiler.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index b67261a1e3e9..3d5af56337bd 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -188,6 +188,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
     (typeof(ptr)) (__ptr + (off)); })
 #endif
 
+#define absolute_pointer(val)	RELOC_HIDE((void *)(val), 0)
+
 #ifndef OPTIMIZER_HIDE_VAR
 /* Make the optimizer believe the variable can be manipulated arbitrarily. */
 #define OPTIMIZER_HIDE_VAR(var)						\
-- 
2.33.0


  reply	other threads:[~2021-09-12 16:01 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-12 16:01 [PATCH 0/4] Introduce and use absolute_pointer macro Guenter Roeck
2021-09-12 16:01 ` Guenter Roeck [this message]
2021-09-12 16:01 ` [PATCH 2/4] net: i825xx: Use absolute_pointer for memcpy on fixed memory location Guenter Roeck
2021-09-12 16:11   ` Jeroen Roovers
2021-09-12 16:16     ` Guenter Roeck
2021-09-12 16:01 ` [PATCH 3/4] parisc: Use absolute_pointer for memcmp " Guenter Roeck
2021-09-12 19:11   ` Linus Torvalds
2021-09-12 19:58     ` Helge Deller
2021-09-12 20:28       ` Guenter Roeck
2021-09-12 16:01 ` [PATCH 4/4] alpha: Use absolute_pointer for strcmp " Guenter Roeck
2021-09-12 19:13   ` Linus Torvalds
2021-09-12 20:15     ` Guenter Roeck
2021-09-12 20:37     ` Guenter Roeck
2021-09-12 22:58       ` Linus Torvalds

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