Merge tag 'x86-boot-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 boot code updates from Ingo Molnar:

 - Memblock setup and other early boot code cleanups (Mike Rapoport)

 - Export e820_table_kexec[] to sysfs (Dave Young)

 - Baby steps of adding relocate_kernel() debugging support (David
   Woodhouse)

 - Replace open-coded parity calculation with parity8() (Kuan-Wei Chiu)

 - Move the LA57 trampoline to separate source file (Ard Biesheuvel)

 - Misc micro-optimizations (Uros Bizjak)

 - Drop obsolete E820_TYPE_RESERVED_KERN and related code (Mike
   Rapoport)

* tag 'x86-boot-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kexec: Add relocate_kernel() debugging support: Load a GDT
  x86/boot: Move the LA57 trampoline to separate source file
  x86/boot: Do not test if AC and ID eflags are changeable on x86_64
  x86/bootflag: Replace open-coded parity calculation with parity8()
  x86/bootflag: Micro-optimize sbf_write()
  x86/boot: Add missing has_cpuflag() prototype
  x86/kexec: Export e820_table_kexec[] to sysfs
  x86/boot: Change some static bootflag functions to bool
  x86/e820: Drop obsolete E820_TYPE_RESERVED_KERN and related code
  x86/boot: Split parsing of boot_params into the parse_boot_params() helper function
  x86/boot: Split kernel resources setup into the setup_kernel_resources() helper function
  x86/boot: Move setting of memblock parameters to e820__memblock_setup()

Author: torvalds

arch/x86/boot/compressed/Makefile

@@ -98,6 +98,7 @@ ifdef CONFIG_X86_64
 	vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/mem_encrypt.o
 	vmlinux-objs-y += $(obj)/pgtable_64.o
 	vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o
+	vmlinux-objs-y += $(obj)/la57toggle.o
 endif
 
 vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o

arch/x86/boot/compressed/head_64.S

@@ -483,110 +483,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
 	jmp	*%rax
 SYM_FUNC_END(.Lrelocated)
 
-/*
- * This is the 32-bit trampoline that will be copied over to low memory. It
- * will be called using the ordinary 64-bit calling convention from code
- * running in 64-bit mode.
- *
- * Return address is at the top of the stack (might be above 4G).
- * The first argument (EDI) contains the address of the temporary PGD level
- * page table in 32-bit addressable memory which will be programmed into
- * register CR3.
- */
-	.section ".rodata", "a", @progbits
-SYM_CODE_START(trampoline_32bit_src)
-	/*
-	 * Preserve callee save 64-bit registers on the stack: this is
-	 * necessary because the architecture does not guarantee that GPRs will
-	 * retain their full 64-bit values across a 32-bit mode switch.
-	 */
-	pushq	%r15
-	pushq	%r14
-	pushq	%r13
-	pushq	%r12
-	pushq	%rbp
-	pushq	%rbx
-
-	/* Preserve top half of RSP in a legacy mode GPR to avoid truncation */
-	movq	%rsp, %rbx
-	shrq	$32, %rbx
-
-	/* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */
-	pushq	$__KERNEL32_CS
-	leaq	0f(%rip), %rax
-	pushq	%rax
-	lretq
-
-	/*
-	 * The 32-bit code below will do a far jump back to long mode and end
-	 * up here after reconfiguring the number of paging levels. First, the
-	 * stack pointer needs to be restored to its full 64-bit value before
-	 * the callee save register contents can be popped from the stack.
-	 */
-.Lret:
-	shlq	$32, %rbx
-	orq	%rbx, %rsp
-
-	/* Restore the preserved 64-bit registers */
-	popq	%rbx
-	popq	%rbp
-	popq	%r12
-	popq	%r13
-	popq	%r14
-	popq	%r15
-	retq
-
 	.code32
-0:
-	/* Disable paging */
-	movl	%cr0, %eax
-	btrl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-
-	/* Point CR3 to the trampoline's new top level page table */
-	movl	%edi, %cr3
-
-	/* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */
-	movl	$MSR_EFER, %ecx
-	rdmsr
-	btsl	$_EFER_LME, %eax
-	/* Avoid writing EFER if no change was made (for TDX guest) */
-	jc	1f
-	wrmsr
-1:
-	/* Toggle CR4.LA57 */
-	movl	%cr4, %eax
-	btcl	$X86_CR4_LA57_BIT, %eax
-	movl	%eax, %cr4
-
-	/* Enable paging again. */
-	movl	%cr0, %eax
-	btsl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-
-	/*
-	 * Return to the 64-bit calling code using LJMP rather than LRET, to
-	 * avoid the need for a 32-bit addressable stack. The destination
-	 * address will be adjusted after the template code is copied into a
-	 * 32-bit addressable buffer.
-	 */
-.Ljmp:	ljmpl	$__KERNEL_CS, $(.Lret - trampoline_32bit_src)
-SYM_CODE_END(trampoline_32bit_src)
-
-/*
- * This symbol is placed right after trampoline_32bit_src() so its address can
- * be used to infer the size of the trampoline code.
- */
-SYM_DATA(trampoline_ljmp_imm_offset, .word  .Ljmp + 1 - trampoline_32bit_src)
-
-	/*
-         * The trampoline code has a size limit.
-         * Make sure we fail to compile if the trampoline code grows
-         * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes.
-	 */
-	.org	trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE
-
-	.text
 SYM_FUNC_START_LOCAL_NOALIGN(.Lno_longmode)
 	/* This isn't an x86-64 CPU, so hang intentionally, we cannot continue */
 1:

arch/x86/boot/compressed/la57toggle.S

@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/linkage.h>
+#include <asm/segment.h>
+#include <asm/boot.h>
+#include <asm/msr.h>
+#include <asm/processor-flags.h>
+#include "pgtable.h"
+
+/*
+ * This is the 32-bit trampoline that will be copied over to low memory. It
+ * will be called using the ordinary 64-bit calling convention from code
+ * running in 64-bit mode.
+ *
+ * Return address is at the top of the stack (might be above 4G).
+ * The first argument (EDI) contains the address of the temporary PGD level
+ * page table in 32-bit addressable memory which will be programmed into
+ * register CR3.
+ */
+
+	.section ".rodata", "a", @progbits
+SYM_CODE_START(trampoline_32bit_src)
+	/*
+	 * Preserve callee save 64-bit registers on the stack: this is
+	 * necessary because the architecture does not guarantee that GPRs will
+	 * retain their full 64-bit values across a 32-bit mode switch.
+	 */
+	pushq	%r15
+	pushq	%r14
+	pushq	%r13
+	pushq	%r12
+	pushq	%rbp
+	pushq	%rbx
+
+	/* Preserve top half of RSP in a legacy mode GPR to avoid truncation */
+	movq	%rsp, %rbx
+	shrq	$32, %rbx
+
+	/* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */
+	pushq	$__KERNEL32_CS
+	leaq	0f(%rip), %rax
+	pushq	%rax
+	lretq
+
+	/*
+	 * The 32-bit code below will do a far jump back to long mode and end
+	 * up here after reconfiguring the number of paging levels. First, the
+	 * stack pointer needs to be restored to its full 64-bit value before
+	 * the callee save register contents can be popped from the stack.
+	 */
+.Lret:
+	shlq	$32, %rbx
+	orq	%rbx, %rsp
+
+	/* Restore the preserved 64-bit registers */
+	popq	%rbx
+	popq	%rbp
+	popq	%r12
+	popq	%r13
+	popq	%r14
+	popq	%r15
+	retq
+
+	.code32
+0:
+	/* Disable paging */
+	movl	%cr0, %eax
+	btrl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
+	/* Point CR3 to the trampoline's new top level page table */
+	movl	%edi, %cr3
+
+	/* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */
+	movl	$MSR_EFER, %ecx
+	rdmsr
+	btsl	$_EFER_LME, %eax
+	/* Avoid writing EFER if no change was made (for TDX guest) */
+	jc	1f
+	wrmsr
+1:
+	/* Toggle CR4.LA57 */
+	movl	%cr4, %eax
+	btcl	$X86_CR4_LA57_BIT, %eax
+	movl	%eax, %cr4
+
+	/* Enable paging again. */
+	movl	%cr0, %eax
+	btsl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
+	/*
+	 * Return to the 64-bit calling code using LJMP rather than LRET, to
+	 * avoid the need for a 32-bit addressable stack. The destination
+	 * address will be adjusted after the template code is copied into a
+	 * 32-bit addressable buffer.
+	 */
+.Ljmp:	ljmpl	$__KERNEL_CS, $(.Lret - trampoline_32bit_src)
+SYM_CODE_END(trampoline_32bit_src)
+
+/*
+ * This symbol is placed right after trampoline_32bit_src() so its address can
+ * be used to infer the size of the trampoline code.
+ */
+SYM_DATA(trampoline_ljmp_imm_offset, .word  .Ljmp + 1 - trampoline_32bit_src)
+
+	/*
+         * The trampoline code has a size limit.
+         * Make sure we fail to compile if the trampoline code grows
+         * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes.
+	 */
+	.org	trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE

arch/x86/boot/cpuflags.c

@@ -28,40 +28,32 @@ static int has_fpu(void)
 	return fsw == 0 && (fcw & 0x103f) == 0x003f;
 }
 
+#ifdef CONFIG_X86_32
 /*
  * For building the 16-bit code we want to explicitly specify 32-bit
  * push/pop operations, rather than just saying 'pushf' or 'popf' and
- * letting the compiler choose. But this is also included from the
- * compressed/ directory where it may be 64-bit code, and thus needs
- * to be 'pushfq' or 'popfq' in that case.
+ * letting the compiler choose.
  */
-#ifdef __x86_64__
-#define PUSHF "pushfq"
-#define POPF "popfq"
-#else
-#define PUSHF "pushfl"
-#define POPF "popfl"
-#endif
-
-int has_eflag(unsigned long mask)
+bool has_eflag(unsigned long mask)
 {
 	unsigned long f0, f1;
 
-	asm volatile(PUSHF "	\n\t"
-		     PUSHF "	\n\t"
+	asm volatile("pushfl	\n\t"
+		     "pushfl	\n\t"
 		     "pop %0	\n\t"
 		     "mov %0,%1	\n\t"
 		     "xor %2,%1	\n\t"
 		     "push %1	\n\t"
-		     POPF "	\n\t"
-		     PUSHF "	\n\t"
+		     "popfl	\n\t"
+		     "pushfl	\n\t"
 		     "pop %1	\n\t"
-		     POPF
+		     "popfl"
 		     : "=&r" (f0), "=&r" (f1)
 		     : "ri" (mask));
 
 	return !!((f0^f1) & mask);
 }
+#endif
 
 void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d)
 {

arch/x86/boot/cpuflags.h

@@ -15,8 +15,13 @@ struct cpu_features {
 extern struct cpu_features cpu;
 extern u32 cpu_vendor[3];
 
-int has_eflag(unsigned long mask);
+#ifdef CONFIG_X86_32
+bool has_eflag(unsigned long mask);
+#else
+static inline bool has_eflag(unsigned long mask) { return true; }
+#endif
 void get_cpuflags(void);
 void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d);
+bool has_cpuflag(int flag);
 
 #endif

arch/x86/include/asm/e820/api.h

@@ -29,7 +29,6 @@ extern unsigned long e820__end_of_low_ram_pfn(void);
 extern u64  e820__memblock_alloc_reserved(u64 size, u64 align);
 extern void e820__memblock_setup(void);
 
-extern void e820__reserve_setup_data(void);
 extern void e820__finish_early_params(void);
 extern void e820__reserve_resources(void);
 extern void e820__reserve_resources_late(void);

arch/x86/include/asm/e820/types.h

@@ -35,15 +35,6 @@ enum e820_type {
 	 * marking it with the IORES_DESC_SOFT_RESERVED designation.
 	 */
 	E820_TYPE_SOFT_RESERVED	= 0xefffffff,
-
-	/*
-	 * Reserved RAM used by the kernel itself if
-	 * CONFIG_INTEL_TXT=y is enabled, memory of this type
-	 * will be included in the S3 integrity calculation
-	 * and so should not include any memory that the BIOS
-	 * might alter over the S3 transition:
-	 */
-	E820_TYPE_RESERVED_KERN	= 128,
 };
 
 /*

arch/x86/kernel/bootflag.c

@@ -8,6 +8,7 @@
 #include <linux/string.h>
 #include <linux/spinlock.h>
 #include <linux/acpi.h>
+#include <linux/bitops.h>
 #include <asm/io.h>
 
 #include <linux/mc146818rtc.h>
@@ -20,27 +21,13 @@
 
 int sbf_port __initdata = -1;	/* set via acpi_boot_init() */
 
-static int __init parity(u8 v)
-{
-	int x = 0;
-	int i;
-
-	for (i = 0; i < 8; i++) {
-		x ^= (v & 1);
-		v >>= 1;
-	}
-
-	return x;
-}
-
 static void __init sbf_write(u8 v)
 {
 	unsigned long flags;
 
 	if (sbf_port != -1) {
-		v &= ~SBF_PARITY;
-		if (!parity(v))
-			v |= SBF_PARITY;
+		if (!parity8(v))
+			v ^= SBF_PARITY;
 
 		printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n",
 			sbf_port, v);
@@ -66,14 +53,14 @@ static u8 __init sbf_read(void)
 	return v;
 }
 
-static int __init sbf_value_valid(u8 v)
+static bool __init sbf_value_valid(u8 v)
 {
 	if (v & SBF_RESERVED)		/* Reserved bits */
-		return 0;
-	if (!parity(v))
-		return 0;
+		return false;
+	if (!parity8(v))
+		return false;
 
-	return 1;
+	return true;
 }
 
 static int __init sbf_init(void)