linux-kernel - [PATCH] x86/EISA: Remedy address space conflict

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Message-ID: <87zfozd6gs.ffs@tglx>
Date: Mon, 26 Aug 2024 10:38:27 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: kernel test robot <lkp@...el.com>, "Maciej W. Rozycki" <macro@...am.me.uk>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [PATCH] x86/EISA: Remedy address space conflict

0-day reported a new sparse warning:
 
  arch/x86/kernel/eisa.c:20:24: sparse:
	incorrect type in argument 1 (different address spaces)
        expected void const volatile [noderef] __iomem *addr
	got void *[assigned] p

Cure it by removing the readl() and dereferencing the pointer directly,
which is correct as it's a memory access.

Reported-by: kernel test robot <lkp@...el.com>
Fixes: 80a4da05642c ("x86/EISA: Use memremap() to probe for the EISA BIOS signature")
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: "Maciej W. Rozycki" <macro@...am.me.uk>
Closes: https://lore.kernel.org/oe-kbuild-all/202408261244.v2gfgSON-lkp@intel.com/
---
 arch/x86/kernel/eisa.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/eisa.c
+++ b/arch/x86/kernel/eisa.c
@@ -11,13 +11,13 @@
 
 static __init int eisa_bus_probe(void)
 {
-	void *p;
+	u32 *p;
 
 	if ((xen_pv_domain() && !xen_initial_domain()) || cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
 		return 0;
 
 	p = memremap(0x0FFFD9, 4, MEMREMAP_WB);
-	if (p && readl(p) == 'E' + ('I' << 8) + ('S' << 16) + ('A' << 24))
+	if (p && *p == 'E' + ('I' << 8) + ('S' << 16) + ('A' << 24))
 		EISA_bus = 1;
 	memunmap(p);
 	return 0;