linux-kernel - [PATCH v3 4/8] x86/idt: remove address argument to idt

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Date:   Wed, 19 May 2021 14:21:50 -0700
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 4/8] x86/idt: remove address argument to idt_invalidate()

From: "H. Peter Anvin (Intel)" <hpa@...or.com>

There is no reason to specify any specific address to
idt_invalidate(). It looks mostly like an artifact of unifying code
done differently by accident. The most "sensible" address to set here
is a NULL pointer - virtual address zero, just as a visual marker.

This also makes it possible to mark the struct desc_ptr in
idt_invalidate() as static const.

Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
---
 arch/x86/include/asm/desc.h        | 2 +-
 arch/x86/kernel/idt.c              | 5 ++---
 arch/x86/kernel/machine_kexec_32.c | 2 +-
 arch/x86/kernel/reboot.c           | 2 +-
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 476082a83d1c..b8429ae50b71 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -427,6 +427,6 @@ static inline void idt_setup_early_pf(void) { }
 static inline void idt_setup_ist_traps(void) { }
 #endif
 
-extern void idt_invalidate(void *addr);
+extern void idt_invalidate(void);
 
 #endif /* _ASM_X86_DESC_H */
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index d552f177eca0..2779f5226dc2 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -331,11 +331,10 @@ void __init idt_setup_early_handler(void)
 
 /**
  * idt_invalidate - Invalidate interrupt descriptor table
- * @addr:	The virtual address of the 'invalid' IDT
  */
-void idt_invalidate(void *addr)
+void idt_invalidate(void)
 {
-	struct desc_ptr idt = { .address = (unsigned long) addr, .size = 0 };
+	static const struct desc_ptr idt = { .address = 0, .size = 0 };
 
 	load_idt(&idt);
 }
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index 64b00b0d7fe8..1e34feebcd5d 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -232,7 +232,7 @@ void machine_kexec(struct kimage *image)
 	 * The gdt & idt are now invalid.
 	 * If you want to load them you must set up your own idt & gdt.
 	 */
-	idt_invalidate(phys_to_virt(0));
+	idt_invalidate();
 	set_gdt(phys_to_virt(0), 0);
 
 	/* now call it */
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index b29657b76e3f..ebfb91108232 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -669,7 +669,7 @@ static void native_machine_emergency_restart(void)
 			break;
 
 		case BOOT_TRIPLE:
-			idt_invalidate(NULL);
+			idt_invalidate();
 			__asm__ __volatile__("int3");
 
 			/* We're probably dead after this, but... */
-- 
2.31.1