linux-kernel - [PATCH v2 6/9] x86/kexec: set_[gi]dt() -> native_[gi]dt_invalidate() in machine_kexec

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Date:   Fri, 14 May 2021 18:43:58 -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 v2 6/9] x86/kexec: set_[gi]dt() -> native_[gi]dt_invalidate() in machine_kexec_*.c

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

These files contain private set_gdt() functions which are only used to
invalid the gdt; machine_kexec_64.c also contains a set_idt()
function to invalidate the idt.

phys_to_virt(0) *really* doesn't make any sense for creating an
invalid GDT. A NULL pointer (virtual 0) makes a lot more sense;
although neither will allow any actual memory reference, a NULL
pointer stands out more.

Replace these calls with native_[gi]dt_invalidate().

Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
---
 arch/x86/kernel/machine_kexec_32.c | 15 ++------------
 arch/x86/kernel/machine_kexec_64.c | 33 ++----------------------------
 2 files changed, 4 insertions(+), 44 deletions(-)

diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c
index 1e34feebcd5d..1b373d79cedc 100644
--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -23,17 +23,6 @@
 #include <asm/set_memory.h>
 #include <asm/debugreg.h>
 
-static void set_gdt(void *newgdt, __u16 limit)
-{
-	struct desc_ptr curgdt;
-
-	/* ia32 supports unaligned loads & stores */
-	curgdt.size    = limit;
-	curgdt.address = (unsigned long)newgdt;
-
-	load_gdt(&curgdt);
-}
-
 static void load_segments(void)
 {
 #define __STR(X) #X
@@ -232,8 +221,8 @@ 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();
-	set_gdt(phys_to_virt(0), 0);
+	native_idt_invalidate();
+	native_gdt_invalidate();
 
 	/* now call it */
 	image->start = relocate_kernel_ptr((unsigned long)image->head,
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index c078b0d3ab0e..131f30fdcfbd 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -256,35 +256,6 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 	return init_transition_pgtable(image, level4p);
 }
 
-static void set_idt(void *newidt, u16 limit)
-{
-	struct desc_ptr curidt;
-
-	/* x86-64 supports unaligned loads & stores */
-	curidt.size    = limit;
-	curidt.address = (unsigned long)newidt;
-
-	__asm__ __volatile__ (
-		"lidtq %0\n"
-		: : "m" (curidt)
-		);
-};
-
-
-static void set_gdt(void *newgdt, u16 limit)
-{
-	struct desc_ptr curgdt;
-
-	/* x86-64 supports unaligned loads & stores */
-	curgdt.size    = limit;
-	curgdt.address = (unsigned long)newgdt;
-
-	__asm__ __volatile__ (
-		"lgdtq %0\n"
-		: : "m" (curgdt)
-		);
-};
-
 static void load_segments(void)
 {
 	__asm__ __volatile__ (
@@ -379,8 +350,8 @@ 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.
 	 */
-	set_gdt(phys_to_virt(0), 0);
-	set_idt(phys_to_virt(0), 0);
+	native_idt_invalidate();
+	native_gdt_invalidate();
 
 	/* now call it */
 	image->start = relocate_kernel((unsigned long)image->head,
-- 
2.31.1