linux-kernel - [PATCH 5.4 01/18] MIPS: Use address-of operator on section symbols

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Date:   Fri, 13 May 2022 16:23:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 5.4 01/18] MIPS: Use address-of operator on section symbols

From: Nathan Chancellor <natechancellor@...il.com>

commit d422c6c0644bccbb1ebeefffa51f35cec3019517 upstream.

When building xway_defconfig with clang:

arch/mips/lantiq/prom.c:82:23: error: array comparison always evaluates
to true [-Werror,-Wtautological-compare]
        else if (__dtb_start != __dtb_end)
                             ^
1 error generated.

These are not true arrays, they are linker defined symbols, which are
just addresses. Using the address of operator silences the warning
and does not change the resulting assembly with either clang/ld.lld
or gcc/ld (tested with diff + objdump -Dr). Do the same thing across
the entire MIPS subsystem to ensure there are no more warnings around
this type of comparison.

Link: https://github.com/ClangBuiltLinux/linux/issues/1232
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
Acked-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Sudip Mukherjee <sudipm.mukherjee@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/mips/bmips/setup.c          |    2 +-
 arch/mips/lantiq/prom.c          |    2 +-
 arch/mips/pic32/pic32mzda/init.c |    2 +-
 arch/mips/ralink/of.c            |    2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -167,7 +167,7 @@ void __init plat_mem_setup(void)
 		dtb = phys_to_virt(fw_arg2);
 	else if (fw_passed_dtb) /* UHI interface or appended dtb */
 		dtb = (void *)fw_passed_dtb;
-	else if (__dtb_start != __dtb_end)
+	else if (&__dtb_start != &__dtb_end)
 		dtb = (void *)__dtb_start;
 	else
 		panic("no dtb found");
--- a/arch/mips/lantiq/prom.c
+++ b/arch/mips/lantiq/prom.c
@@ -79,7 +79,7 @@ void __init plat_mem_setup(void)
 
 	if (fw_passed_dtb) /* UHI interface */
 		dtb = (void *)fw_passed_dtb;
-	else if (__dtb_start != __dtb_end)
+	else if (&__dtb_start != &__dtb_end)
 		dtb = (void *)__dtb_start;
 	else
 		panic("no dtb found");
--- a/arch/mips/pic32/pic32mzda/init.c
+++ b/arch/mips/pic32/pic32mzda/init.c
@@ -28,7 +28,7 @@ static ulong get_fdtaddr(void)
 	if (fw_passed_dtb && !fw_arg2 && !fw_arg3)
 		return (ulong)fw_passed_dtb;
 
-	if (__dtb_start < __dtb_end)
+	if (&__dtb_start < &__dtb_end)
 		ftaddr = (ulong)__dtb_start;
 
 	return ftaddr;
--- a/arch/mips/ralink/of.c
+++ b/arch/mips/ralink/of.c
@@ -77,7 +77,7 @@ void __init plat_mem_setup(void)
 	 */
 	if (fw_passed_dtb)
 		dtb = (void *)fw_passed_dtb;
-	else if (__dtb_start != __dtb_end)
+	else if (&__dtb_start != &__dtb_end)
 		dtb = (void *)__dtb_start;
 
 	__dt_setup_arch(dtb);