x86/asm: Always set A (accessed) flag in GDT descriptors

We have no known use for having the CPU track whether GDT descriptors
have been accessed or not.

Simplify the code by adding the flag to the common flags and removing
it everywhere else.
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231219151200.2878271-5-vegard.nossum@oracle.com

arch/x86/boot/pm.c

@@ -68,9 +68,9 @@ static void setup_gdt(void)
 	   being 8-byte unaligned.  Intel recommends 16 byte alignment. */
 	static const u64 boot_gdt[] __attribute__((aligned(16))) = {
 		/* CS: code, read/execute, 4 GB, base 0 */
-		[GDT_ENTRY_BOOT_CS] = GDT_ENTRY(DESC_CODE32 | _DESC_ACCESSED, 0, 0xfffff),
+		[GDT_ENTRY_BOOT_CS] = GDT_ENTRY(DESC_CODE32, 0, 0xfffff),
 		/* DS: data, read/write, 4 GB, base 0 */
-		[GDT_ENTRY_BOOT_DS] = GDT_ENTRY(DESC_DATA32 | _DESC_ACCESSED, 0, 0xfffff),
+		[GDT_ENTRY_BOOT_DS] = GDT_ENTRY(DESC_DATA32, 0, 0xfffff),
 		/* TSS: 32-bit tss, 104 bytes, base 4096 */
 		/* We only have a TSS here to keep Intel VT happy;
 		   we don't actually use it for anything. */

arch/x86/include/asm/desc_defs.h

@@ -37,9 +37,9 @@
  * of flags
  */
 
-#define _DESC_DATA		(_DESC_S | _DESC_PRESENT | \
+#define _DESC_DATA		(_DESC_S | _DESC_PRESENT | _DESC_ACCESSED | \
 				 _DESC_DATA_WRITABLE)
-#define _DESC_CODE		(_DESC_S | _DESC_PRESENT | \
+#define _DESC_CODE		(_DESC_S | _DESC_PRESENT | _DESC_ACCESSED | \
 				 _DESC_CODE_READABLE | _DESC_CODE_EXECUTABLE)
 
 #define DESC_DATA16		(_DESC_DATA)

arch/x86/kernel/cpu/common.c

@@ -188,12 +188,12 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
 	 * TLS descriptors are currently at a different place compared to i386.
 	 * Hopefully nobody expects them at a fixed place (Wine?)
 	 */
-	[GDT_ENTRY_KERNEL32_CS]		= GDT_ENTRY_INIT(DESC_CODE32 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_KERNEL_CS]		= GDT_ENTRY_INIT(DESC_CODE64 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_KERNEL_DS]		= GDT_ENTRY_INIT(DESC_DATA64 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_DEFAULT_USER32_CS]	= GDT_ENTRY_INIT(DESC_CODE32 | DESC_USER | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_DEFAULT_USER_DS]	= GDT_ENTRY_INIT(DESC_DATA64 | DESC_USER | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_DEFAULT_USER_CS]	= GDT_ENTRY_INIT(DESC_CODE64 | DESC_USER | _DESC_ACCESSED, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL32_CS]		= GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL_CS]		= GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL_DS]		= GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
+	[GDT_ENTRY_DEFAULT_USER32_CS]	= GDT_ENTRY_INIT(DESC_CODE32 | DESC_USER, 0, 0xfffff),
+	[GDT_ENTRY_DEFAULT_USER_DS]	= GDT_ENTRY_INIT(DESC_DATA64 | DESC_USER, 0, 0xfffff),
+	[GDT_ENTRY_DEFAULT_USER_CS]	= GDT_ENTRY_INIT(DESC_CODE64 | DESC_USER, 0, 0xfffff),
 #else
 	[GDT_ENTRY_KERNEL_CS]		= GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
 	[GDT_ENTRY_KERNEL_DS]		= GDT_ENTRY_INIT(DESC_DATA32, 0, 0xfffff),

arch/x86/kernel/head64.c

@@ -71,9 +71,9 @@ EXPORT_SYMBOL(vmemmap_base);
  * GDT used on the boot CPU before switching to virtual addresses.
  */
 static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
-	[GDT_ENTRY_KERNEL32_CS]         = GDT_ENTRY_INIT(DESC_CODE32 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_KERNEL_CS]           = GDT_ENTRY_INIT(DESC_CODE64 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_KERNEL_DS]           = GDT_ENTRY_INIT(DESC_DATA64 | _DESC_ACCESSED, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL32_CS]         = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL_CS]           = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL_DS]           = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
 };
 
 /*

arch/x86/realmode/rm/reboot.S

@@ -154,5 +154,5 @@ SYM_DATA_START(machine_real_restart_gdt)
 	 * base value 0x100; since this is consistent with real mode
 	 * semantics we don't have to reload the segments once CR0.PE = 0.
 	 */
-	.quad	GDT_ENTRY(DESC_DATA16 | _DESC_ACCESSED, 0x100, 0xffff)
+	.quad	GDT_ENTRY(DESC_DATA16, 0x100, 0xffff)
 SYM_DATA_END(machine_real_restart_gdt)

drivers/firmware/efi/libstub/x86-5lvl.c

@@ -13,8 +13,8 @@ bool efi_no5lvl;
 static void (*la57_toggle)(void *cr3);
 
 static const struct desc_struct gdt[] = {
-	[GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32 | _DESC_ACCESSED, 0, 0xfffff),
-	[GDT_ENTRY_KERNEL_CS]   = GDT_ENTRY_INIT(DESC_CODE64 | _DESC_ACCESSED, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
+	[GDT_ENTRY_KERNEL_CS]   = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
 };
 
 /*