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linux/arch/x86/include/asm/kexec.h
David Woodhouse 7516e7216b x86/kexec: Add 8250 MMIO serial port output 
This supports the same 32-bit MMIO-mapped 8250 as the early_printk code.

It's not clear why the early_printk code supports this form and only this
form; the actual runtime 8250_pci doesn't seem to support it. But having
hacked up QEMU to expose such a device, early_printk does work with it,
and now so does the kexec debug code.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250326142404.256980-3-dwmw2@infradead.org
2025-04-10 12:17:14 +02:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_KEXEC_H
#define _ASM_X86_KEXEC_H
#ifdef CONFIG_X86_32
# define PA_CONTROL_PAGE 0
# define VA_CONTROL_PAGE 1
# define PA_PGD 2
# define PA_SWAP_PAGE 3
# define PAGES_NR 4
#else
/* Size of each exception handler referenced by the IDT */
# define KEXEC_DEBUG_EXC_HANDLER_SIZE 6 /* PUSHI, PUSHI, 2-byte JMP */
#endif
# define KEXEC_CONTROL_PAGE_SIZE 4096
# define KEXEC_CONTROL_CODE_MAX_SIZE 2048
#ifndef __ASSEMBLER__
#include <linux/string.h>
#include <linux/kernel.h>
#include <asm/asm.h>
#include <asm/page.h>
#include <asm/ptrace.h>
struct kimage;
/*
* KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
* I.e. Maximum page that is mapped directly into kernel memory,
* and kmap is not required.
*
* So far x86_64 is limited to 40 physical address bits.
*/
#ifdef CONFIG_X86_32
/* Maximum physical address we can use pages from */
# define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
/* Maximum address we can reach in physical address mode */
# define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
/* Maximum address we can use for the control code buffer */
# define KEXEC_CONTROL_MEMORY_LIMIT TASK_SIZE
/* The native architecture */
# define KEXEC_ARCH KEXEC_ARCH_386
/* We can also handle crash dumps from 64 bit kernel. */
# define vmcore_elf_check_arch_cross(x) ((x)->e_machine == EM_X86_64)
#else
/* Maximum physical address we can use pages from */
# define KEXEC_SOURCE_MEMORY_LIMIT (MAXMEM-1)
/* Maximum address we can reach in physical address mode */
# define KEXEC_DESTINATION_MEMORY_LIMIT (MAXMEM-1)
/* Maximum address we can use for the control pages */
# define KEXEC_CONTROL_MEMORY_LIMIT (MAXMEM-1)
/* The native architecture */
# define KEXEC_ARCH KEXEC_ARCH_X86_64
extern unsigned long kexec_va_control_page;
extern unsigned long kexec_pa_table_page;
extern unsigned long kexec_pa_swap_page;
extern gate_desc kexec_debug_idt[];
extern unsigned char kexec_debug_exc_vectors[];
extern uint16_t kexec_debug_8250_port;
extern unsigned long kexec_debug_8250_mmio32;
#endif
/*
* This function is responsible for capturing register states if coming
* via panic otherwise just fix up the ss and sp if coming via kernel
* mode exception.
*/
static inline void crash_setup_regs(struct pt_regs *newregs,
struct pt_regs *oldregs)
{
if (oldregs) {
memcpy(newregs, oldregs, sizeof(*newregs));
} else {
asm volatile("mov %%" _ASM_BX ",%0" : "=m"(newregs->bx));
asm volatile("mov %%" _ASM_CX ",%0" : "=m"(newregs->cx));
asm volatile("mov %%" _ASM_DX ",%0" : "=m"(newregs->dx));
asm volatile("mov %%" _ASM_SI ",%0" : "=m"(newregs->si));
asm volatile("mov %%" _ASM_DI ",%0" : "=m"(newregs->di));
asm volatile("mov %%" _ASM_BP ",%0" : "=m"(newregs->bp));
asm volatile("mov %%" _ASM_AX ",%0" : "=m"(newregs->ax));
asm volatile("mov %%" _ASM_SP ",%0" : "=m"(newregs->sp));
#ifdef CONFIG_X86_64
asm volatile("mov %%r8,%0" : "=m"(newregs->r8));
asm volatile("mov %%r9,%0" : "=m"(newregs->r9));
asm volatile("mov %%r10,%0" : "=m"(newregs->r10));
asm volatile("mov %%r11,%0" : "=m"(newregs->r11));
asm volatile("mov %%r12,%0" : "=m"(newregs->r12));
asm volatile("mov %%r13,%0" : "=m"(newregs->r13));
asm volatile("mov %%r14,%0" : "=m"(newregs->r14));
asm volatile("mov %%r15,%0" : "=m"(newregs->r15));
#endif
asm volatile("mov %%ss,%k0" : "=a"(newregs->ss));
asm volatile("mov %%cs,%k0" : "=a"(newregs->cs));
#ifdef CONFIG_X86_32
asm volatile("mov %%ds,%k0" : "=a"(newregs->ds));
asm volatile("mov %%es,%k0" : "=a"(newregs->es));
#endif
asm volatile("pushf\n\t"
"pop %0" : "=m"(newregs->flags));
newregs->ip = _THIS_IP_;
}
}
#ifdef CONFIG_X86_32
typedef asmlinkage unsigned long
relocate_kernel_fn(unsigned long indirection_page,
unsigned long control_page,
unsigned long start_address,
unsigned int has_pae,
unsigned int preserve_context);
#else
typedef unsigned long
relocate_kernel_fn(unsigned long indirection_page,
unsigned long pa_control_page,
unsigned long start_address,
unsigned int preserve_context,
unsigned int host_mem_enc_active);
#endif
extern relocate_kernel_fn relocate_kernel;
#define ARCH_HAS_KIMAGE_ARCH
#ifdef CONFIG_X86_32
struct kimage_arch {
pgd_t *pgd;
#ifdef CONFIG_X86_PAE
pmd_t *pmd0;
pmd_t *pmd1;
#endif
pte_t *pte0;
pte_t *pte1;
};
#else
struct kimage_arch {
/*
* This is a kimage control page, as it must not overlap with either
* source or destination address ranges.
*/
pgd_t *pgd;
/*
* The virtual mapping of the control code page itself is used only
* during the transition, while the current kernel's pages are all
* in place. Thus the intermediate page table pages used to map it
* are not control pages, but instead just normal pages obtained
* with get_zeroed_page(). And have to be tracked (below) so that
* they can be freed.
*/
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
};
#endif /* CONFIG_X86_32 */
#ifdef CONFIG_X86_64
/*
* Number of elements and order of elements in this structure should match
* with the ones in arch/x86/purgatory/entry64.S. If you make a change here
* make an appropriate change in purgatory too.
*/
struct kexec_entry64_regs {
uint64_t rax;
uint64_t rcx;
uint64_t rdx;
uint64_t rbx;
uint64_t rsp;
uint64_t rbp;
uint64_t rsi;
uint64_t rdi;
uint64_t r8;
uint64_t r9;
uint64_t r10;
uint64_t r11;
uint64_t r12;
uint64_t r13;
uint64_t r14;
uint64_t r15;
uint64_t rip;
};
extern int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages,
gfp_t gfp);
#define arch_kexec_post_alloc_pages arch_kexec_post_alloc_pages
extern void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages);
#define arch_kexec_pre_free_pages arch_kexec_pre_free_pages
void arch_kexec_protect_crashkres(void);
#define arch_kexec_protect_crashkres arch_kexec_protect_crashkres
void arch_kexec_unprotect_crashkres(void);
#define arch_kexec_unprotect_crashkres arch_kexec_unprotect_crashkres
#ifdef CONFIG_KEXEC_FILE
struct purgatory_info;
int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
Elf_Shdr *section,
const Elf_Shdr *relsec,
const Elf_Shdr *symtab);
#define arch_kexec_apply_relocations_add arch_kexec_apply_relocations_add
int arch_kimage_file_post_load_cleanup(struct kimage *image);
#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup
#endif
#endif
extern void kdump_nmi_shootdown_cpus(void);
#ifdef CONFIG_CRASH_HOTPLUG
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg);
#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event
int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags);
#define arch_crash_hotplug_support arch_crash_hotplug_support
unsigned int arch_crash_get_elfcorehdr_size(void);
#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size
#endif
#endif /* __ASSEMBLER__ */
#endif /* _ASM_X86_KEXEC_H */
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