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Re: [PATCH 1/6] add support for booting from grub with x86_64
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From: |
Samuel Thibault |
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Subject: |
Re: [PATCH 1/6] add support for booting from grub with x86_64 |
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Date: |
Sat, 27 Aug 2022 20:55:51 +0200 |
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User-agent: |
NeoMutt/20170609 (1.8.3) |
Luca Dariz, le sam. 05 févr. 2022 18:51:24 +0100, a ecrit:
> * configure: compile for native x86_64 by default instead of xen
> * x86_64/Makefrag.am: introduce KERNEL_MAP_BASE to reuse the constant
> in both code and linker script
> * x86_64/ldscript: use a .boot section for the very first operations,
> until we reach long mode. This section is not really allocated, so
> it doesn't need to be freed later. The vm system is later
> initialized starting from .text and not including .boot
> * link kernel at 0x4000000 as the xen version, higher values causes
> linker errors
> * we can't use full segmentation in long mode, so we need to create a
> temporary mapping during early boot to be able to jump to high
> addresses
> * build direct map for first 4G in boothdr, it seems required by Linux
> drivers
> * add INTEL_PTE_PS bit definition to enable 2MB pages during bootstrap
> * ensure write bit is set in PDP entry access rights. This only
> applies to PAE-enabled kernels, mandatory for x86_64. On xen
> platform it seems to be handled differently
>
> Signed-off-by: Luca Dariz <luca@orpolo.org>
Applied, thanks!
> ---
> configure.ac | 3 +-
> i386/configfrag.ac | 2 +
> i386/i386/i386asm.sym | 1 +
> i386/i386/vm_param.h | 2 +-
> i386/intel/pmap.c | 4 +-
> i386/intel/pmap.h | 1 +
> x86_64/Makefrag.am | 18 +++-
> x86_64/boothdr.S | 238 ++++++++++++++++++++++++++++++++++++++++++
> x86_64/ldscript | 28 +++--
> 9 files changed, 281 insertions(+), 16 deletions(-)
> create mode 100644 x86_64/boothdr.S
>
> diff --git a/configure.ac b/configure.ac
> index 019842db..3aaa935c 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -56,8 +56,7 @@ case $host_platform:$host_cpu in
> default:i?86)
> host_platform=at;;
> default:x86_64)]
> - AC_MSG_WARN([Platform set to Xen by default, this can not boot on
> non-Xen systems, you currently need a 32bit build for that.])
> - [host_platform=xen;;
> + [host_platform=at;;
> at:i?86 | xen:i?86 | at:x86_64 | xen:x86_64)
> :;;
> *)]
> diff --git a/i386/configfrag.ac b/i386/configfrag.ac
> index f697e277..f07a98ca 100644
> --- a/i386/configfrag.ac
> +++ b/i386/configfrag.ac
> @@ -106,6 +106,8 @@ AC_ARG_ENABLE([apic],
> enable_pae=${enable_pae-yes};;
> *:i?86)
> :;;
> + *:x86_64)
> + enable_pae=${enable_pae-yes};;
> *)
> if [ x"$enable_pae" = xyes ]; then]
> AC_MSG_ERROR([can only enable the `PAE' feature on ix86.])
> diff --git a/i386/i386/i386asm.sym b/i386/i386/i386asm.sym
> index 0662aea0..9e1d13d7 100644
> --- a/i386/i386/i386asm.sym
> +++ b/i386/i386/i386asm.sym
> @@ -122,6 +122,7 @@ expr sizeof(pt_entry_t)
> PTE_SIZE
> expr INTEL_PTE_PFN PTE_PFN
> expr INTEL_PTE_VALID PTE_V
> expr INTEL_PTE_WRITE PTE_W
> +expr INTEL_PTE_PS PTE_S
> expr ~INTEL_PTE_VALID PTE_INVALID
> expr NPTES PTES_PER_PAGE
> expr INTEL_PTE_VALID|INTEL_PTE_WRITE INTEL_PTE_KERNEL
> diff --git a/i386/i386/vm_param.h b/i386/i386/vm_param.h
> index edd9522c..314fdb35 100644
> --- a/i386/i386/vm_param.h
> +++ b/i386/i386/vm_param.h
> @@ -36,7 +36,7 @@
> * for better trace support in kdb; the _START symbol has to be offset by the
> * same amount. */
> #ifdef __x86_64__
> -#define VM_MIN_KERNEL_ADDRESS 0x40000000UL
> +#define VM_MIN_KERNEL_ADDRESS KERNEL_MAP_BASE
> #else
> #define VM_MIN_KERNEL_ADDRESS 0xC0000000UL
> #endif
> diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c
> index 3bf00659..d0bd3b5d 100644
> --- a/i386/intel/pmap.c
> +++ b/i386/intel/pmap.c
> @@ -655,7 +655,7 @@ void pmap_bootstrap(void)
> pa_to_pte(_kvtophys((void *) kernel_page_dir
> + i * INTEL_PGBYTES))
> | INTEL_PTE_VALID
> -#ifdef MACH_PV_PAGETABLES
> +#if !defined(MACH_HYP) || defined(MACH_PV_PAGETABLES)
> | INTEL_PTE_WRITE
> #endif
> );
> @@ -1297,7 +1297,7 @@ pmap_t pmap_create(vm_size_t size)
> WRITE_PTE(&p->pdpbase[i],
> pa_to_pte(kvtophys((vm_offset_t) page_dir[i]))
> | INTEL_PTE_VALID
> -#ifdef MACH_PV_PAGETABLES
> +#if !defined(MACH_HYP) || defined(MACH_PV_PAGETABLES)
> | INTEL_PTE_WRITE
> #endif
> );
> diff --git a/i386/intel/pmap.h b/i386/intel/pmap.h
> index f24b3a71..b93c4ad4 100644
> --- a/i386/intel/pmap.h
> +++ b/i386/intel/pmap.h
> @@ -148,6 +148,7 @@ typedef phys_addr_t pt_entry_t;
> #define INTEL_PTE_NCACHE 0x00000010
> #define INTEL_PTE_REF 0x00000020
> #define INTEL_PTE_MOD 0x00000040
> +#define INTEL_PTE_PS 0x00000080
> #ifdef MACH_PV_PAGETABLES
> /* Not supported */
> #define INTEL_PTE_GLOBAL 0x00000000
> diff --git a/x86_64/Makefrag.am b/x86_64/Makefrag.am
> index 40b50bc9..5da734de 100644
> --- a/x86_64/Makefrag.am
> +++ b/x86_64/Makefrag.am
> @@ -207,11 +207,27 @@ nodist_libkernel_a_SOURCES += \
>
> EXTRA_DIST += \
> x86_64/ldscript
> +
> if PLATFORM_at
> +# This should probably be 0xffffffff80000000 for mcmodel=kernel, but let's
> try
> +# to stay in the first 8G first, otherwise we have to fix the pmap module to
> +# actually use the l4 page level
> +#KERNEL_MAP_BASE=0x100000000
> +# but for nor try with < 4G, otherwise we have linker errors
> +KERNEL_MAP_BASE=0x40000000
> gnumach_LINKFLAGS += \
> --defsym _START_MAP=$(_START_MAP) \
> - --defsym _START=_START_MAP+0x40000000 \
> + --defsym _START=_START_MAP \
> + --defsym KERNEL_MAP_BASE=$(KERNEL_MAP_BASE) \
> -T '$(srcdir)'/x86_64/ldscript
> +
> +AM_CFLAGS += -D_START_MAP=$(_START_MAP) \
> + -DKERNEL_MAP_BASE=$(KERNEL_MAP_BASE)
> +AM_CCASFLAGS += -D_START_MAP=$(_START_MAP) \
> + -DKERNEL_MAP_BASE=$(KERNEL_MAP_BASE)
> +
> +AM_CCASFLAGS += \
> + -Ii386
> endif
>
> AM_CPPFLAGS += \
> diff --git a/x86_64/boothdr.S b/x86_64/boothdr.S
> new file mode 100644
> index 00000000..12fc7ca2
> --- /dev/null
> +++ b/x86_64/boothdr.S
> @@ -0,0 +1,238 @@
> +/*
> + * Copyright (C) 2022 Free Software Foundation
> + *
> + * This program is free software ; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation ; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY ; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with the program ; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <mach/machine/asm.h>
> +
> +#include <i386/i386asm.h>
> +#include <i386/i386/proc_reg.h>
> +#include <i386/i386/seg.h>
> + /*
> + * This section will be put first into .boot. See also x86_64/ldscript.
> + */
> + .section .boot.text,"ax"
> + .globl boot_start
> +
> + /* We should never be entered this way. */
> + .code32
> +boot_start:
> + jmp boot_entry
> +
> + /* MultiBoot header - see multiboot.h. */
> +#define MULTIBOOT_MAGIC 0x1BADB002
> +#ifdef __ELF__
> +#define MULTIBOOT_FLAGS 0x00000003
> +#else /* __ELF__ */
> +#define MULTIBOOT_FLAGS 0x00010003
> +#endif /* __ELF__ */
> + P2ALIGN(2)
> +boot_hdr:
> + .long MULTIBOOT_MAGIC
> + .long MULTIBOOT_FLAGS
> + /*
> + * The next item here is the checksum.
> + * XX this works OK until we need at least the 30th bit.
> + */
> + .long - (MULTIBOOT_MAGIC+MULTIBOOT_FLAGS)
> +#ifndef __ELF__ /* a.out kludge */
> + .long boot_hdr /* header_addr */
> + .long _start /* load_addr */
> + .long _edata /* load_end_addr */
> + .long _end /* bss_end_addr */
> + .long boot_entry /* entry */
> +#endif /* __ELF__ */
> +
> +boot_entry:
> + /*
> + * Prepare minimal page mapping to jump to 64 bit and to C code.
> + * The first 4GB is identity mapped, and the first 2GB are re-mapped
> + * to high addresses at KERNEL_MAP_BASE
> + */
> +
> + movl $p3table,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p4table)
> + /*
> + * Fill 4 entries in L3 table to cover the whole 32-bit 4GB address
> + * space. Part of it might be remapped later if the kernel is mapped
> + * below 4G.
> + */
> + movl $p2table,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table)
> + movl $p2table1,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table + 8)
> + movl $p2table2,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table + 16)
> + movl $p2table3,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table + 24)
> + /* point each page table level two entry to a page */
> + mov $0,%ecx
> +.map_p2_table:
> + mov $0x200000,%eax // 2MiB page, should be always available
> + mul %ecx
> + or $(PTE_V|PTE_W|PTE_S),%eax // enable 2MiB page instead of 4k
> + mov %eax,p2table(,%ecx,8)
> + inc %ecx
> + cmp $2048,%ecx // 512 entries per table, map 4 L2 tables
> + jne .map_p2_table
> +
> + /*
> + * KERNEL_MAP_BASE must me aligned to 2GB.
> + * Depending on kernel starting address, we might need to add another
> + * entry in the L4 table (controlling 512 GB chunks). In any case, we
> + * add two entries in L3 table to make sure we map 2GB for the kernel.
> + * Note that this may override part of the mapping create above.
> + */
> +.kernel_map:
> +#if KERNEL_MAP_BASE >= (1U << 39)
> + movl $p3ktable,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p4table + (8 * ((KERNEL_MAP_BASE >> 39) & 0x1FF))) //
> select 512G block
> + movl $p2ktable1,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3ktable + (8 * ((KERNEL_MAP_BASE >> 30) & 0x1FF) )) //
> select first 1G block
> + movl $p2ktable2,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3ktable + (8 * (((KERNEL_MAP_BASE >> 30) & 0x1FF) + 1)
> )) // select second 1G block
> +#else
> + movl $p2ktable1,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table + (8 * ((KERNEL_MAP_BASE >> 30) & 0x1FF) )) //
> select first 1G block
> + movl $p2ktable2,%eax
> + or $(PTE_V|PTE_W),%eax
> + movl %eax,(p3table + (8 * (((KERNEL_MAP_BASE >> 30) & 0x1FF) + 1) ))
> // select second 1G block
> +#endif
> +
> + mov $0,%ecx
> +.map_p2k_table:
> + mov $0x200000,%eax // 2MiB page, should be always available
> + mul %ecx
> + or $(PTE_V|PTE_W|PTE_S),%eax // enable 2MiB page instead of 4K
> + mov %eax,p2ktable1(,%ecx,8)
> + inc %ecx
> + cmp $1024,%ecx // 512 entries per table, map 2 L2 tables
> + jne .map_p2k_table
> +
> +switch64:
> + /*
> + * Jump to 64 bit mode, we have to
> + * - enable PAE
> + * - enable long mode
> + * - enable paging and load the tables filled above in CR3
> + * - jump to a 64-bit code segment
> + */
> + mov %cr4,%eax
> + or $CR4_PAE,%eax
> + mov %eax,%cr4
> + mov $0xC0000080,%ecx // select EFER register
> + rdmsr
> + or $(1 << 8),%eax // long mode enable bit
> + wrmsr
> + mov $p4table,%eax
> + mov %eax,%cr3
> + mov %cr0,%eax
> + or $CR0_PG,%eax
> + or $CR0_WP,%eax
> + mov %eax,%cr0
> +
> + lgdt gdt64pointer
> + movw $0,%ax
> + movw %ax,%fs
> + movw %ax,%gs
> + movw $16,%ax
> + movw %ax,%ds
> + movw %ax,%es
> + movw %ax,%ss
> + ljmp $8,$boot_entry64
> +
> + .code64
> +
> + /* why do we need this? it seems overwritten by linker */
> + .globl _start
> +_start:
> +
> +boot_entry64:
> + /* Switch to our own interrupt stack. */
> + movq $(_intstack+INTSTACK_SIZE),%rax
> + andq $(~15),%rax
> + movq %rax,%rsp
> +
> + /* Reset EFLAGS to a known state. */
> + pushq $0
> + popf
> + /* save multiboot info for later */
> + movq %rbx,%r8
> +
> + /* Fix ifunc entries */
> + movq $__rela_iplt_start,%rsi
> + movq $__rela_iplt_end,%rdi
> +iplt_cont:
> + cmpq %rdi,%rsi
> + jae iplt_done
> + movq (%rsi),%rbx /* r_offset */
> + movb 4(%rsi),%al /* info */
> + cmpb $42,%al /* IRELATIVE */
> + jnz iplt_next
> + call *(%ebx) /* call ifunc */
> + movq %rax,(%rbx) /* fixed address */
> +iplt_next:
> + addq $8,%rsi
> + jmp iplt_cont
> +iplt_done:
> +
> + /* restore multiboot info */
> + movq %r8,%rdi
> + /* Jump into C code. */
> + call EXT(c_boot_entry)
> + /* not reached */
> + nop
> +
> + .section .boot.data
> + .comm _intstack,INTSTACK_SIZE
> +
> + .code32
> + .section .boot.data
> + .align 4096
> +#define SEG_ACCESS_OFS 40
> +#define SEG_GRANULARITY_OFS 52
> +gdt64:
> + .quad 0
> +gdt64code:
> + .quad (ACC_P << SEG_ACCESS_OFS) | (ACC_CODE_R <<
> SEG_ACCESS_OFS) | (SZ_64 << SEG_GRANULARITY_OFS)
> +gdt64data:
> + .quad (ACC_P << SEG_ACCESS_OFS) | (ACC_DATA_W <<
> SEG_ACCESS_OFS)
> +gdt64end:
> + .skip (4096 - (gdt64end - gdt64))
> +gdt64pointer:
> + .word gdt64end - gdt64 - 1
> + .quad gdt64
> +
> + .section .boot.data
> + .align 4096
> +p4table: .space 4096
> +p3table: .space 4096
> +p2table: .space 4096
> +p2table1: .space 4096
> +p2table2: .space 4096
> +p2table3: .space 4096
> +p3ktable: .space 4096
> +p2ktable1: .space 4096
> +p2ktable2: .space 4096
> diff --git a/x86_64/ldscript b/x86_64/ldscript
> index 375e8104..de99795e 100644
> --- a/x86_64/ldscript
> +++ b/x86_64/ldscript
> @@ -2,7 +2,7 @@
> OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64",
> "elf64-x86-64")
> OUTPUT_ARCH(i386:x86-64)
> -ENTRY(_start)
> +ENTRY(boot_start)
> SECTIONS
> {
> /*
> @@ -11,22 +11,30 @@ SECTIONS
> * be first in there. See also `i386/i386at/boothdr.S' and
> * `gnumach_LINKFLAGS' in `i386/Makefrag.am'.
> */
> - . = _START;
> - .text :
> - AT (_START_MAP)
> +
> + . = _START_MAP;
> + .boot :
> + {
> + *(.boot.text)
> + *(.boot.data)
> + } =0x90909090
> +
> + . += KERNEL_MAP_BASE;
> + _start = .;
> + .text : AT(((ADDR(.text)) - KERNEL_MAP_BASE))
> {
> - *(.text.start)
> + *(.text*)
> *(.text .stub .text.* .gnu.linkonce.t.*)
> *(.text.unlikely .text.*_unlikely)
> KEEP (*(.text.*personality*))
> /* .gnu.warning sections are handled specially by elf32.em. */
> *(.gnu.warning)
> } =0x90909090
> - .init :
> + .init : AT(((ADDR(.init)) - KERNEL_MAP_BASE))
> {
> KEEP (*(.init))
> } =0x90909090
> - .fini :
> + .fini : AT(((ADDR(.fini)) - KERNEL_MAP_BASE))
> {
> KEEP (*(.fini))
> } =0x90909090
> @@ -69,7 +77,7 @@ SECTIONS
> PROVIDE_HIDDEN (__rela_iplt_end = .);
> }
> .plt : { *(.plt) *(.iplt) }
> - .rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
> + .rodata : AT(((ADDR(.rodata)) - KERNEL_MAP_BASE)) { *(.rodata
> .rodata.* .gnu.linkonce.r.*) }
> .rodata1 : { *(.rodata1) }
> .eh_frame_hdr : { *(.eh_frame_hdr) }
> .eh_frame : ONLY_IF_RO { KEEP (*(.eh_frame)) }
> @@ -139,7 +147,7 @@ SECTIONS
> .got : { *(.got) *(.igot) }
> . = DATA_SEGMENT_RELRO_END (24, .);
> .got.plt : { *(.got.plt) *(.igot.plt) }
> - .data :
> + .data : AT(((ADDR(.data)) - KERNEL_MAP_BASE))
> {
> *(.data .data.* .gnu.linkonce.d.*)
> SORT(CONSTRUCTORS)
> @@ -147,7 +155,7 @@ SECTIONS
> .data1 : { *(.data1) }
> _edata = .; PROVIDE (edata = .);
> __bss_start = .;
> - .bss :
> + .bss : AT(((ADDR(.bss)) - KERNEL_MAP_BASE))
> {
> *(.dynbss)
> *(.bss .bss.* .gnu.linkonce.b.*)
> --
> 2.30.2
>
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.