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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-06 01:02:30 +0000 |
commit | 76cb841cb886eef6b3bee341a2266c76578724ad (patch) | |
tree | f5892e5ba6cc11949952a6ce4ecbe6d516d6ce58 /arch/x86/boot/pm.c | |
parent | Initial commit. (diff) | |
download | linux-76cb841cb886eef6b3bee341a2266c76578724ad.tar.xz linux-76cb841cb886eef6b3bee341a2266c76578724ad.zip |
Adding upstream version 4.19.249.upstream/4.19.249upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/x86/boot/pm.c')
-rw-r--r-- | arch/x86/boot/pm.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/arch/x86/boot/pm.c b/arch/x86/boot/pm.c new file mode 100644 index 000000000..8062f8915 --- /dev/null +++ b/arch/x86/boot/pm.c @@ -0,0 +1,126 @@ +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright 2007 rPath, Inc. - All Rights Reserved + * + * This file is part of the Linux kernel, and is made available under + * the terms of the GNU General Public License version 2. + * + * ----------------------------------------------------------------------- */ + +/* + * Prepare the machine for transition to protected mode. + */ + +#include "boot.h" +#include <asm/segment.h> + +/* + * Invoke the realmode switch hook if present; otherwise + * disable all interrupts. + */ +static void realmode_switch_hook(void) +{ + if (boot_params.hdr.realmode_swtch) { + asm volatile("lcallw *%0" + : : "m" (boot_params.hdr.realmode_swtch) + : "eax", "ebx", "ecx", "edx"); + } else { + asm volatile("cli"); + outb(0x80, 0x70); /* Disable NMI */ + io_delay(); + } +} + +/* + * Disable all interrupts at the legacy PIC. + */ +static void mask_all_interrupts(void) +{ + outb(0xff, 0xa1); /* Mask all interrupts on the secondary PIC */ + io_delay(); + outb(0xfb, 0x21); /* Mask all but cascade on the primary PIC */ + io_delay(); +} + +/* + * Reset IGNNE# if asserted in the FPU. + */ +static void reset_coprocessor(void) +{ + outb(0, 0xf0); + io_delay(); + outb(0, 0xf1); + io_delay(); +} + +/* + * Set up the GDT + */ + +struct gdt_ptr { + u16 len; + u32 ptr; +} __attribute__((packed)); + +static void setup_gdt(void) +{ + /* There are machines which are known to not boot with the GDT + 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(0xc09b, 0, 0xfffff), + /* DS: data, read/write, 4 GB, base 0 */ + [GDT_ENTRY_BOOT_DS] = GDT_ENTRY(0xc093, 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. */ + [GDT_ENTRY_BOOT_TSS] = GDT_ENTRY(0x0089, 4096, 103), + }; + /* Xen HVM incorrectly stores a pointer to the gdt_ptr, instead + of the gdt_ptr contents. Thus, make it static so it will + stay in memory, at least long enough that we switch to the + proper kernel GDT. */ + static struct gdt_ptr gdt; + + gdt.len = sizeof(boot_gdt)-1; + gdt.ptr = (u32)&boot_gdt + (ds() << 4); + + asm volatile("lgdtl %0" : : "m" (gdt)); +} + +/* + * Set up the IDT + */ +static void setup_idt(void) +{ + static const struct gdt_ptr null_idt = {0, 0}; + asm volatile("lidtl %0" : : "m" (null_idt)); +} + +/* + * Actual invocation sequence + */ +void go_to_protected_mode(void) +{ + /* Hook before leaving real mode, also disables interrupts */ + realmode_switch_hook(); + + /* Enable the A20 gate */ + if (enable_a20()) { + puts("A20 gate not responding, unable to boot...\n"); + die(); + } + + /* Reset coprocessor (IGNNE#) */ + reset_coprocessor(); + + /* Mask all interrupts in the PIC */ + mask_all_interrupts(); + + /* Actual transition to protected mode... */ + setup_idt(); + setup_gdt(); + protected_mode_jump(boot_params.hdr.code32_start, + (u32)&boot_params + (ds() << 4)); +} |