Changes in this cycle:

- Robustify/fix calling startup_{32,64}() from the decompressor code,
    and removing x86 quirk from scripts/head-object-list.txt as
    a result.
 
  - Do not register processors that cannot be onlined for x2APIC
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-boot-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 boot updates from Ingo Molnar:

 - Robustify/fix calling startup_{32,64}() from the decompressor code,
   and removing x86 quirk from scripts/head-object-list.txt as a result.

 - Do not register processors that cannot be onlined for x2APIC

* tag 'x86-boot-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/acpi/boot: Do not register processors that cannot be onlined for x2APIC
  scripts/head-object-list: Remove x86 from the list
  x86/boot: Robustify calling startup_{32,64}() from the decompressor code

arch/x86/boot/compressed/head_32.S

@@ -187,7 +187,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
 	leal	boot_heap@GOTOFF(%ebx), %eax
 	pushl	%eax			/* heap area */
 	pushl	%esi			/* real mode pointer */
-	call	extract_kernel		/* returns kernel location in %eax */
+	call	extract_kernel		/* returns kernel entry point in %eax */
 	addl	$24, %esp
 
 /*

arch/x86/boot/compressed/head_64.S

@@ -569,7 +569,7 @@ SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated)
 	movl	input_len(%rip), %ecx	/* input_len */
 	movq	%rbp, %r8		/* output target address */
 	movl	output_len(%rip), %r9d	/* decompressed length, end of relocs */
-	call	extract_kernel		/* returns kernel location in %rax */
+	call	extract_kernel		/* returns kernel entry point in %rax */
 	popq	%rsi
 
 /*

arch/x86/boot/compressed/misc.c

@@ -277,7 +277,7 @@ static inline void handle_relocations(void *output, unsigned long output_len,
 { }
 #endif
 
-static void parse_elf(void *output)
+static size_t parse_elf(void *output)
 {
 #ifdef CONFIG_X86_64
 	Elf64_Ehdr ehdr;
@@ -293,10 +293,8 @@ static void parse_elf(void *output)
 	if (ehdr.e_ident[EI_MAG0] != ELFMAG0 ||
 	   ehdr.e_ident[EI_MAG1] != ELFMAG1 ||
 	   ehdr.e_ident[EI_MAG2] != ELFMAG2 ||
-	   ehdr.e_ident[EI_MAG3] != ELFMAG3) {
+	   ehdr.e_ident[EI_MAG3] != ELFMAG3)
 		error("Kernel is not a valid ELF file");
-		return;
-	}
 
 	debug_putstr("Parsing ELF... ");
 
@@ -328,6 +326,8 @@ static void parse_elf(void *output)
 	}
 
 	free(phdrs);
+
+	return ehdr.e_entry - LOAD_PHYSICAL_ADDR;
 }
 
 /*
@@ -356,6 +356,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 	const unsigned long kernel_total_size = VO__end - VO__text;
 	unsigned long virt_addr = LOAD_PHYSICAL_ADDR;
 	unsigned long needed_size;
+	size_t entry_offset;
 
 	/* Retain x86 boot parameters pointer passed from startup_32/64. */
 	boot_params = rmode;
@@ -456,14 +457,17 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 	debug_putstr("\nDecompressing Linux... ");
 	__decompress(input_data, input_len, NULL, NULL, output, output_len,
 			NULL, error);
-	parse_elf(output);
+	entry_offset = parse_elf(output);
 	handle_relocations(output, output_len, virt_addr);
-	debug_putstr("done.\nBooting the kernel.\n");
+
+	debug_putstr("done.\nBooting the kernel (entry_offset: 0x");
+	debug_puthex(entry_offset);
+	debug_putstr(").\n");
 
 	/* Disable exception handling before booting the kernel */
 	cleanup_exception_handling();
 
-	return output;
+	return output + entry_offset;
 }
 
 void fortify_panic(const char *name)

arch/x86/kernel/acpi/boot.c

@@ -188,6 +188,17 @@ static int acpi_register_lapic(int id, u32 acpiid, u8 enabled)
 	return cpu;
 }
 
+static bool __init acpi_is_processor_usable(u32 lapic_flags)
+{
+	if (lapic_flags & ACPI_MADT_ENABLED)
+		return true;
+
+	if (acpi_support_online_capable && (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
+		return true;
+
+	return false;
+}
+
 static int __init
 acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
 {
@@ -212,6 +223,10 @@ acpi_parse_x2apic(union acpi_subtable_headers *header, const unsigned long end)
 	if (apic_id == 0xffffffff)
 		return 0;
 
+	/* don't register processors that cannot be onlined */
+	if (!acpi_is_processor_usable(processor->lapic_flags))
+		return 0;
+
 	/*
 	 * We need to register disabled CPU as well to permit
 	 * counting disabled CPUs. This allows us to size
@@ -250,9 +265,7 @@ acpi_parse_lapic(union acpi_subtable_headers * header, const unsigned long end)
 		return 0;
 
 	/* don't register processors that can not be onlined */
-	if (acpi_support_online_capable &&
-	    !(processor->lapic_flags & ACPI_MADT_ENABLED) &&
-	    !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
+	if (!acpi_is_processor_usable(processor->lapic_flags))
 		return 0;
 
 	/*

scripts/head-object-list.txt

@@ -42,10 +42,4 @@ arch/s390/kernel/head64.o
 arch/sh/kernel/head_32.o
 arch/sparc/kernel/head_32.o
 arch/sparc/kernel/head_64.o
-arch/x86/kernel/head_32.o
-arch/x86/kernel/head_64.o
-arch/x86/kernel/head32.o
-arch/x86/kernel/head64.o
-arch/x86/kernel/ebda.o
-arch/x86/kernel/platform-quirks.o
 arch/xtensa/kernel/head.o