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No more intel/minix segments.

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This commit removes all traces of Minix segments (the text/data/stack
memory map abstraction in the kernel) and significance of Intel segments
(hardware segments like CS, DS that add offsets to all addressing before
page table translation). This ultimately simplifies the memory layout
and addressing and makes the same layout possible on non-Intel
architectures.

There are only two types of addresses in the world now: virtual
and physical; even the kernel and processes have the same virtual
address space. Kernel and user processes can be distinguished at a
glance as processes won't use 0xF0000000 and above.

No static pre-allocated memory sizes exist any more.

Changes to booting:
        . The pre_init.c leaves the kernel and modules exactly as
          they were left by the bootloader in physical memory
        . The kernel starts running using physical addressing,
          loaded at a fixed location given in its linker script by the
          bootloader.  All code and data in this phase are linked to
          this fixed low location.
        . It makes a bootstrap pagetable to map itself to a
          fixed high location (also in linker script) and jumps to
          the high address. All code and data then use this high addressing.
        . All code/data symbols linked at the low addresses is prefixed by
          an objcopy step with __k_unpaged_*, so that that code cannot
          reference highly-linked symbols (which aren't valid yet) or vice
          versa (symbols that aren't valid any more).
        . The two addressing modes are separated in the linker script by
          collecting the unpaged_*.o objects and linking them with low
          addresses, and linking the rest high. Some objects are linked
          twice, once low and once high.
        . The bootstrap phase passes a lot of information (e.g. free memory
          list, physical location of the modules, etc.) using the kinfo
          struct.
        . After this bootstrap the low-linked part is freed.
        . The kernel maps in VM into the bootstrap page table so that VM can
          begin executing. Its first job is to make page tables for all other
          boot processes. So VM runs before RS, and RS gets a fully dynamic,
          VM-managed address space. VM gets its privilege info from RS as usual
          but that happens after RS starts running.
        . Both the kernel loading VM and VM organizing boot processes happen
	  using the libexec logic. This removes the last reason for VM to
	  still know much about exec() and vm/exec.c is gone.

Further Implementation:
        . All segments are based at 0 and have a 4 GB limit.
        . The kernel is mapped in at the top of the virtual address
          space so as not to constrain the user processes.
        . Processes do not use segments from the LDT at all; there are
          no segments in the LDT any more, so no LLDT is needed.
        . The Minix segments T/D/S are gone and so none of the
          user-space or in-kernel copy functions use them. The copy
          functions use a process endpoint of NONE to realize it's
          a physical address, virtual otherwise.
        . The umap call only makes sense to translate a virtual address
          to a physical address now.
        . Segments-related calls like newmap and alloc_segments are gone.
        . All segments-related translation in VM is gone (vir2map etc).
        . Initialization in VM is simpler as no moving around is necessary.
        . VM and all other boot processes can be linked wherever they wish
          and will be mapped in at the right location by the kernel and VM
          respectively.

Other changes:
        . The multiboot code is less special: it does not use mb_print
          for its diagnostics any more but uses printf() as normal, saving
          the output into the diagnostics buffer, only printing to the
          screen using the direct print functions if a panic() occurs.
        . The multiboot code uses the flexible 'free memory map list'
          style to receive the list of free memory if available.
        . The kernel determines the memory layout of the processes to
          a degree: it tells VM where the kernel starts and ends and
          where the kernel wants the top of the process to be. VM then
          uses this entire range, i.e. the stack is right at the top,
          and mmap()ped bits of memory are placed below that downwards,
          and the break grows upwards.

Other Consequences:
        . Every process gets its own page table as address spaces
          can't be separated any more by segments.
        . As all segments are 0-based, there is no distinction between
          virtual and linear addresses, nor between userspace and
          kernel addresses.
        . Less work is done when context switching, leading to a net
          performance increase. (8% faster on my machine for 'make servers'.)
	. The layout and configuration of the GDT makes sysenter and syscall
	  possible.
This commit is contained in:
Ben Gras
2012-05-07 16:03:35 +02:00
parent cfe1ed4df4
commit 50e2064049
139 changed files with 2468 additions and 4380 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
include/arch/i386/include/archtypes.h
View File

@@ -14,24 +14,19 @@ struct segdesc_s { /* segment descriptor for protected mode */
u8_t access; /* |P|DL|1|X|E|R|A| */
u8_t granularity; /* |G|X|0|A|LIMT| */
u8_t base_high;
};
} __attribute__((packed));
#define LDT_SIZE 2 /* CS and DS */
/* Fixed local descriptors. */
#define CS_LDT_INDEX 0 /* process CS */
#define DS_LDT_INDEX 1 /* process DS=ES=FS=GS=SS */
struct desctableptr_s {
u16_t limit;
u32_t base;
} __attribute__((packed));
typedef struct segframe {
reg_t p_ldt_sel; /* selector in gdt with ldt base and limit */
reg_t p_cr3; /* page table root */
u32_t *p_cr3_v;
char *fpu_state;
struct segdesc_s p_ldt[LDT_SIZE]; /* CS, DS and remote */
} segframe_t;
#define INMEMORY(p) (!p->p_seg.p_cr3 || get_cpulocal_var(ptproc) == p)
typedef u32_t atomic_t; /* access to an aligned 32bit value is atomic on i386 */
#endif /* #ifndef _I386_TYPES_H */

19
include/arch/i386/include/interrupt.h
View File

@@ -14,6 +14,9 @@
/* Magic numbers for interrupt controller. */
#define END_OF_INT 0x20 /* code used to re-enable after an interrupt */
#define IRQ0_VECTOR 0x50 /* nice vectors to relocate IRQ0-7 to */
#define IRQ8_VECTOR 0x70 /* no need to move IRQ8-15 */
/* Interrupt vectors defined/reserved by processor. */
#define DIVIDE_VECTOR 0 /* divide error */
#define DEBUG_VECTOR 1 /* single step (trace) */
@@ -25,15 +28,6 @@
#define KERN_CALL_VECTOR 32 /* system calls are made with int SYSVEC */
#define IPC_VECTOR 33 /* interrupt vector for ipc */
/* Suitable irq bases for hardware interrupts. Reprogram the 8259(s) from
* the PC BIOS defaults since the BIOS doesn't respect all the processor's
* reserved vectors (0 to 31).
*/
#define BIOS_IRQ0_VEC 0x08 /* base of IRQ0-7 vectors used by BIOS */
#define BIOS_IRQ8_VEC 0x70 /* base of IRQ8-15 vectors used by BIOS */
#define IRQ0_VECTOR 0x50 /* nice vectors to relocate IRQ0-7 to */
#define IRQ8_VECTOR 0x70 /* no need to move IRQ8-15 */
/* Hardware interrupt numbers. */
#ifndef USE_APIC
#define NR_IRQ_VECTORS 16
@@ -55,11 +49,8 @@
#define AT_WINI_0_IRQ 14 /* at winchester controller 0 */
#define AT_WINI_1_IRQ 15 /* at winchester controller 1 */
/* Interrupt number to hardware vector. */
#define BIOS_VECTOR(irq) \
(((irq) < 8 ? BIOS_IRQ0_VEC : BIOS_IRQ8_VEC) + ((irq) & 0x07))
#define VECTOR(irq) \
(((irq) < 8 ? IRQ0_VECTOR : IRQ8_VECTOR) + ((irq) & 0x07))
#define VECTOR(irq) \
(((irq) < 8 ? IRQ0_VECTOR : IRQ8_VECTOR) + ((irq) & 0x07))
#endif /* (CHIP == INTEL) */

27
include/arch/i386/include/multiboot.h
View File

@@ -14,8 +14,6 @@
#define MULTIBOOT_AOUT_KLUDGE 0x00010000
#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO | MULTIBOOT_PAGE_ALIGN)
/* consts used for Multiboot pre-init */
#define MULTIBOOT_VIDEO_MODE_EGA 1
@@ -28,13 +26,18 @@
#define MULTIBOOT_CONSOLE_LINES 25
#define MULTIBOOT_CONSOLE_COLS 80
#define MULTIBOOT_VIDEO_BUFFER_BYTES \
(MULTIBOOT_CONSOLE_LINES*MULTIBOOT_CONSOLE_COLS*2)
#define MULTIBOOT_STACK_SIZE 4096
#define MULTIBOOT_PARAM_BUF_SIZE 1024
#define MULTIBOOT_MAX_MODS 20
/* Flags to be set in the ’flags’ member of the multiboot info structure. */
#define MULTIBOOT_INFO_MEMORY 0x00000001
#define MULTIBOOT_INFO_MEM_MAP 0x00000040
/* Is there a boot device set? */
#define MULTIBOOT_INFO_BOOTDEV 0x00000002
@@ -45,6 +48,8 @@
/* Are there modules to do something with? */
#define MULTIBOOT_INFO_MODS 0x00000008
#define MULTIBOOT_HIGH_MEM_BASE 0x100000
#ifndef __ASSEMBLY__
#include <minix/types.h>
@@ -73,8 +78,8 @@ struct multiboot_info
/* Multiboot info version number */
u32_t flags;
/* Available memory from BIOS */
u32_t mem_lower;
u32_t mem_upper;
u32_t mem_lower_unused; /* minix uses memmap instead */
u32_t mem_upper_unused;
/* "root" partition */
u32_t boot_device;
/* Kernel command line */
@@ -121,8 +126,18 @@ struct multiboot_mod_list
};
typedef struct multiboot_mod_list multiboot_module_t;
/* Buffer for multiboot parameters */
extern char multiboot_param_buf[];
#define MULTIBOOT_MEMORY_AVAILABLE 1
#define MULTIBOOT_MEMORY_RESERVED 2
struct multiboot_mmap_entry
{
u32_t size;
u64_t addr;
u64_t len;
#define MULTIBOOT_MEMORY_AVAILABLE 1
#define MULTIBOOT_MEMORY_RESERVED 2
u32_t type;
} __attribute__((packed));
typedef struct multiboot_mmap_entry multiboot_memory_map_t;
#endif /* __ASSEMBLY__ */
#endif /* __MULTIBOOT_H__ */

5
include/arch/i386/include/vmparam.h
View File

@@ -49,9 +49,4 @@
#define PAGE_SIZE (1 << PAGE_SHIFT)
#define PAGE_MASK (PAGE_SIZE - 1)
/* As visible from the user space process, where is the top of the
* stack (first non-stack byte), when in paged mode?
*/
#define VM_STACKTOP 0x80000000
#endif /* _I386_VMPARAM_H_ */