linux-kernel - [PATCH] x86: asm/io.h: Harden virt_to_phys/isa_virt_to

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Message-ID: <168146523405.6279.3632248068235163346.stgit@skinsburskii.localdomain>
Date:   Fri, 14 Apr 2023 02:40:34 -0700
From:   Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Stanislav Kinsburskii <stanislav.kinsburskii@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Chris Down <chris@...isdown.name>,
        Helge Deller <deller@....de>, Omar Sandoval <osandov@...com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86: asm/io.h: Harden virt_to_phys/isa_virt_to_bus prototypes

From: Stanislav Kinsburskii <stanislav.kinsburskii@...il.com>

These two helper functions - virt_to_phys and isa_virt_to_bus - don't need the
address pointer to be mutable.

In the same time expecting it to be mutable leads to the following build
warning for constant pointers:

  warning: passing argument 1 of ‘virt_to_phys’ discards ‘const’ qualifier from pointer target type

Signed-off-by: Stanislav Kinsburskii <stanislav.kinsburskii@...il.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Ingo Molnar <mingo@...hat.com>
CC: Borislav Petkov <bp@...en8.de>
CC: Dave Hansen <dave.hansen@...ux.intel.com>
CC: x86@...nel.org
CC: "H. Peter Anvin" <hpa@...or.com>
CC: Geert Uytterhoeven <geert@...ux-m68k.org>
CC: Arnd Bergmann <arnd@...db.de>
CC: Chris Down <chris@...isdown.name>
CC: Helge Deller <deller@....de>
CC: Omar Sandoval <osandov@...com>
CC: linux-kernel@...r.kernel.org
---
 arch/x86/include/asm/io.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index e9025640f634..0e6f5b48f517 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -128,7 +128,7 @@ extern int valid_mmap_phys_addr_range(unsigned long pfn, size_t size);
  *	this function
  */
 
-static inline phys_addr_t virt_to_phys(volatile void *address)
+static inline phys_addr_t virt_to_phys(const volatile void *address)
 {
 	return __pa(address);
 }
@@ -163,7 +163,7 @@ static inline void *phys_to_virt(phys_addr_t address)
  * However, we truncate the address to unsigned int to avoid undesirable
  * promotions in legacy drivers.
  */
-static inline unsigned int isa_virt_to_bus(volatile void *address)
+static inline unsigned int isa_virt_to_bus(const volatile void *address)
 {
 	return (unsigned int)virt_to_phys(address);
 }