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minix/kernel/arch/i386/protect.c
Ben Gras 0cfff08e56 libexec: mmap support, prealloc variants 
In libexec, split the memory allocation method into cleared and
non-cleared. Cleared gives zeroed memory, non-cleared gives 'junk'
memory (that will be overwritten anyway, and so needn't be cleared)
that is faster to get.

Also introduce the 'memmap' method that can be used, if available,
to map code and data from executables into a process using the
third-party mmap() mode.

Change-Id: I26694fd3c21deb8b97e01ed675dfc14719b0672b
2013-04-24 10:18:16 +00:00

438 lines
13 KiB
C
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/* This file contains code for initialization of protected mode, to initialize
* code and data segment descriptors, and to initialize global descriptors
* for local descriptors in the process table.
*/
#include <string.h>
#include <assert.h>
#include <minix/cpufeature.h>
#include <machine/multiboot.h>
#include "kernel/kernel.h"
#include "archconst.h"
#include "arch_proto.h"
#include <libexec.h>
#define INT_GATE_TYPE (INT_286_GATE | DESC_386_BIT)
#define TSS_TYPE (AVL_286_TSS | DESC_386_BIT)
/* This is OK initially, when the 1:1 mapping is still there. */
char *video_mem = (char *) MULTIBOOT_VIDEO_BUFFER;
/* Storage for gdt, idt and tss. */
struct segdesc_s gdt[GDT_SIZE] __aligned(DESC_SIZE);
struct gatedesc_s idt[IDT_SIZE] __aligned(DESC_SIZE);
struct tss_s tss[CONFIG_MAX_CPUS];
u32_t k_percpu_stacks[CONFIG_MAX_CPUS];
int prot_init_done = 0;
phys_bytes vir2phys(void *vir)
{
extern char _kern_vir_base, _kern_phys_base; /* in kernel.lds */
u32_t offset = (vir_bytes) &_kern_vir_base -
(vir_bytes) &_kern_phys_base;
return (phys_bytes)vir - offset;
}
/*===========================================================================*
* enable_iop *
*===========================================================================*/
void enable_iop(struct proc *pp)
{
/* Allow a user process to use I/O instructions. Change the I/O Permission
* Level bits in the psw. These specify least-privileged Current Permission
* Level allowed to execute I/O instructions. Users and servers have CPL 3.
* You can't have less privilege than that. Kernel has CPL 0, tasks CPL 1.
*/
pp->p_reg.psw |= 0x3000;
}
/*===========================================================================*
* sdesc *
*===========================================================================*/
void sdesc(struct segdesc_s *segdp, phys_bytes base, vir_bytes size)
{
/* Fill in the size fields (base, limit and granularity) of a descriptor. */
segdp->base_low = base;
segdp->base_middle = base >> BASE_MIDDLE_SHIFT;
segdp->base_high = base >> BASE_HIGH_SHIFT;
--size; /* convert to a limit, 0 size means 4G */
if (size > BYTE_GRAN_MAX) {
segdp->limit_low = size >> PAGE_GRAN_SHIFT;
segdp->granularity = GRANULAR | (size >>
(PAGE_GRAN_SHIFT + GRANULARITY_SHIFT));
} else {
segdp->limit_low = size;
segdp->granularity = size >> GRANULARITY_SHIFT;
}
segdp->granularity |= DEFAULT; /* means BIG for data seg */
}
/*===========================================================================*
* init_dataseg *
*===========================================================================*/
void init_param_dataseg(register struct segdesc_s *segdp,
phys_bytes base, vir_bytes size, const int privilege)
{
/* Build descriptor for a data segment. */
sdesc(segdp, base, size);
segdp->access = (privilege << DPL_SHIFT) | (PRESENT | SEGMENT |
WRITEABLE | ACCESSED);
/* EXECUTABLE = 0, EXPAND_DOWN = 0, ACCESSED = 0 */
}
void init_dataseg(int index, const int privilege)
{
init_param_dataseg(&gdt[index], 0, 0xFFFFFFFF, privilege);
}
/*===========================================================================*
* init_codeseg *
*===========================================================================*/
static void init_codeseg(int index, int privilege)
{
/* Build descriptor for a code segment. */
sdesc(&gdt[index], 0, 0xFFFFFFFF);
gdt[index].access = (privilege << DPL_SHIFT)
| (PRESENT | SEGMENT | EXECUTABLE | READABLE);
/* CONFORMING = 0, ACCESSED = 0 */
}
static struct gate_table_s gate_table_pic[] = {
{ hwint00, VECTOR( 0), INTR_PRIVILEGE },
{ hwint01, VECTOR( 1), INTR_PRIVILEGE },
{ hwint02, VECTOR( 2), INTR_PRIVILEGE },
{ hwint03, VECTOR( 3), INTR_PRIVILEGE },
{ hwint04, VECTOR( 4), INTR_PRIVILEGE },
{ hwint05, VECTOR( 5), INTR_PRIVILEGE },
{ hwint06, VECTOR( 6), INTR_PRIVILEGE },
{ hwint07, VECTOR( 7), INTR_PRIVILEGE },
{ hwint08, VECTOR( 8), INTR_PRIVILEGE },
{ hwint09, VECTOR( 9), INTR_PRIVILEGE },
{ hwint10, VECTOR(10), INTR_PRIVILEGE },
{ hwint11, VECTOR(11), INTR_PRIVILEGE },
{ hwint12, VECTOR(12), INTR_PRIVILEGE },
{ hwint13, VECTOR(13), INTR_PRIVILEGE },
{ hwint14, VECTOR(14), INTR_PRIVILEGE },
{ hwint15, VECTOR(15), INTR_PRIVILEGE },
{ NULL, 0, 0}
};
static struct gate_table_s gate_table_exceptions[] = {
{ divide_error, DIVIDE_VECTOR, INTR_PRIVILEGE },
{ single_step_exception, DEBUG_VECTOR, INTR_PRIVILEGE },
{ nmi, NMI_VECTOR, INTR_PRIVILEGE },
{ breakpoint_exception, BREAKPOINT_VECTOR, USER_PRIVILEGE },
{ overflow, OVERFLOW_VECTOR, USER_PRIVILEGE },
{ bounds_check, BOUNDS_VECTOR, INTR_PRIVILEGE },
{ inval_opcode, INVAL_OP_VECTOR, INTR_PRIVILEGE },
{ copr_not_available, COPROC_NOT_VECTOR, INTR_PRIVILEGE },
{ double_fault, DOUBLE_FAULT_VECTOR, INTR_PRIVILEGE },
{ copr_seg_overrun, COPROC_SEG_VECTOR, INTR_PRIVILEGE },
{ inval_tss, INVAL_TSS_VECTOR, INTR_PRIVILEGE },
{ segment_not_present, SEG_NOT_VECTOR, INTR_PRIVILEGE },
{ stack_exception, STACK_FAULT_VECTOR, INTR_PRIVILEGE },
{ general_protection, PROTECTION_VECTOR, INTR_PRIVILEGE },
{ page_fault, PAGE_FAULT_VECTOR, INTR_PRIVILEGE },
{ copr_error, COPROC_ERR_VECTOR, INTR_PRIVILEGE },
{ alignment_check, ALIGNMENT_CHECK_VECTOR, INTR_PRIVILEGE },
{ machine_check, MACHINE_CHECK_VECTOR, INTR_PRIVILEGE },
{ simd_exception, SIMD_EXCEPTION_VECTOR, INTR_PRIVILEGE },
{ ipc_entry_softint_orig, IPC_VECTOR_ORIG, USER_PRIVILEGE },
{ kernel_call_entry_orig, KERN_CALL_VECTOR_ORIG, USER_PRIVILEGE },
{ ipc_entry_softint_um, IPC_VECTOR_UM, USER_PRIVILEGE },
{ kernel_call_entry_um, KERN_CALL_VECTOR_UM, USER_PRIVILEGE },
{ NULL, 0, 0}
};
int tss_init(unsigned cpu, void * kernel_stack)
{
struct tss_s * t = &tss[cpu];
int index = TSS_INDEX(cpu);
struct segdesc_s *tssgdt;
tssgdt = &gdt[index];
init_param_dataseg(tssgdt, (phys_bytes) t,
sizeof(struct tss_s), INTR_PRIVILEGE);
tssgdt->access = PRESENT | (INTR_PRIVILEGE << DPL_SHIFT) | TSS_TYPE;
/* Build TSS. */
memset(t, 0, sizeof(*t));
t->ds = t->es = t->fs = t->gs = t->ss0 = KERN_DS_SELECTOR;
t->cs = KERN_CS_SELECTOR;
t->iobase = sizeof(struct tss_s); /* empty i/o permissions map */
/*
* make space for process pointer and cpu id and point to the first
* usable word
*/
k_percpu_stacks[cpu] = t->sp0 = ((unsigned) kernel_stack) - X86_STACK_TOP_RESERVED;
/*
* set the cpu id at the top of the stack so we know on which cpu is
* this stak in use when we trap to kernel
*/
*((reg_t *)(t->sp0 + 1 * sizeof(reg_t))) = cpu;
/* Set up Intel SYSENTER support if available. */
if(minix_feature_flags & MKF_I386_INTEL_SYSENTER) {
ia32_msr_write(INTEL_MSR_SYSENTER_CS, 0, KERN_CS_SELECTOR);
ia32_msr_write(INTEL_MSR_SYSENTER_ESP, 0, t->sp0);
ia32_msr_write(INTEL_MSR_SYSENTER_EIP, 0, (u32_t) ipc_entry_sysenter);
}
/* Set up AMD SYSCALL support if available. */
if(minix_feature_flags & MKF_I386_AMD_SYSCALL) {
u32_t msr_lo, msr_hi;
/* set SYSCALL ENABLE bit in EFER MSR */
ia32_msr_read(AMD_MSR_EFER, &msr_hi, &msr_lo);
msr_lo |= AMD_EFER_SCE;
ia32_msr_write(AMD_MSR_EFER, msr_hi, msr_lo);
/* set STAR register value */
#define set_star_cpu(forcpu) if(cpu == forcpu) { \
ia32_msr_write(AMD_MSR_STAR, \
((u32_t)USER_CS_SELECTOR << 16) | (u32_t)KERN_CS_SELECTOR, \
(u32_t) ipc_entry_syscall_cpu ## forcpu); }
set_star_cpu(0);
set_star_cpu(1);
set_star_cpu(2);
set_star_cpu(3);
set_star_cpu(4);
set_star_cpu(5);
set_star_cpu(6);
set_star_cpu(7);
assert(CONFIG_MAX_CPUS <= 8);
}
return SEG_SELECTOR(index);
}
phys_bytes init_segdesc(int gdt_index, void *base, int size)
{
struct desctableptr_s *dtp = (struct desctableptr_s *) &gdt[gdt_index];
dtp->limit = size - 1;
dtp->base = (phys_bytes) base;
return (phys_bytes) dtp;
}
void int_gate(struct gatedesc_s *tab,
unsigned vec_nr, vir_bytes offset, unsigned dpl_type)
{
/* Build descriptor for an interrupt gate. */
register struct gatedesc_s *idp;
idp = &tab[vec_nr];
idp->offset_low = offset;
idp->selector = KERN_CS_SELECTOR;
idp->p_dpl_type = dpl_type;
idp->offset_high = offset >> OFFSET_HIGH_SHIFT;
}
void int_gate_idt(unsigned vec_nr, vir_bytes offset, unsigned dpl_type)
{
int_gate(idt, vec_nr, offset, dpl_type);
}
void idt_copy_vectors(struct gate_table_s * first)
{
struct gate_table_s *gtp;
for (gtp = first; gtp->gate; gtp++) {
int_gate(idt, gtp->vec_nr, (vir_bytes) gtp->gate,
PRESENT | INT_GATE_TYPE |
(gtp->privilege << DPL_SHIFT));
}
}
void idt_copy_vectors_pic(void)
{
idt_copy_vectors(gate_table_pic);
}
void idt_init(void)
{
idt_copy_vectors_pic();
idt_copy_vectors(gate_table_exceptions);
}
struct desctableptr_s gdt_desc, idt_desc;
void idt_reload(void)
{
x86_lidt(&idt_desc);
}
multiboot_module_t *bootmod(int pnr)
{
int i;
assert(pnr >= 0);
/* Search for desired process in boot process
* list. The first NR_TASKS ones do not correspond
* to a module, however, so we don't search those.
*/
for(i = NR_TASKS; i < NR_BOOT_PROCS; i++) {
int p;
p = i - NR_TASKS;
if(image[i].proc_nr == pnr) {
assert(p < MULTIBOOT_MAX_MODS);
assert(p < kinfo.mbi.mods_count);
return &kinfo.module_list[p];
}
}
panic("boot module %d not found", pnr);
}
int booting_cpu = 0;
void prot_load_selectors(void)
{
/* this function is called by both prot_init by the BSP and
* the early AP booting code in mpx.S by secondary CPU's.
* everything is set up the same except for the TSS that is per-CPU.
*/
x86_lgdt(&gdt_desc); /* Load gdt */
idt_init();
idt_reload();
x86_lldt(LDT_SELECTOR); /* Load bogus ldt */
x86_ltr(TSS_SELECTOR(booting_cpu));
x86_load_kerncs();
x86_load_ds(KERN_DS_SELECTOR);
x86_load_es(KERN_DS_SELECTOR);
x86_load_fs(KERN_DS_SELECTOR);
x86_load_gs(KERN_DS_SELECTOR);
x86_load_ss(KERN_DS_SELECTOR);
}
/*===========================================================================*
* prot_init *
*===========================================================================*/
void prot_init()
{
extern char k_boot_stktop;
if(_cpufeature(_CPUF_I386_SYSENTER))
minix_feature_flags |= MKF_I386_INTEL_SYSENTER;
if(_cpufeature(_CPUF_I386_SYSCALL))
minix_feature_flags |= MKF_I386_AMD_SYSCALL;
memset(gdt, 0, sizeof(gdt));
memset(idt, 0, sizeof(idt));
/* Build GDT, IDT, IDT descriptors. */
gdt_desc.base = (u32_t) gdt;
gdt_desc.limit = sizeof(gdt)-1;
idt_desc.base = (u32_t) idt;
idt_desc.limit = sizeof(idt)-1;
tss_init(0, &k_boot_stktop);
/* Build GDT */
init_param_dataseg(&gdt[LDT_INDEX],
(phys_bytes) 0, 0, INTR_PRIVILEGE); /* unusable LDT */
gdt[LDT_INDEX].access = PRESENT | LDT;
init_codeseg(KERN_CS_INDEX, INTR_PRIVILEGE);
init_dataseg(KERN_DS_INDEX, INTR_PRIVILEGE);
init_codeseg(USER_CS_INDEX, USER_PRIVILEGE);
init_dataseg(USER_DS_INDEX, USER_PRIVILEGE);
/* Currently the multiboot segments are loaded; which is fine, but
* let's replace them with the ones from our own GDT so we test
* right away whether they work as expected.
*/
prot_load_selectors();
/* Set up a new post-relocate bootstrap pagetable so that
* we can map in VM, and we no longer rely on pre-relocated
* data.
*/
pg_clear();
pg_identity(&kinfo); /* Still need 1:1 for lapic and video mem and such. */
pg_mapkernel();
pg_load();
prot_init_done = 1;
}
static int alloc_for_vm = 0;
void arch_post_init(void)
{
/* Let memory mapping code know what's going on at bootstrap time */
struct proc *vm;
vm = proc_addr(VM_PROC_NR);
get_cpulocal_var(ptproc) = vm;
pg_info(&vm->p_seg.p_cr3, &vm->p_seg.p_cr3_v);
}
int libexec_pg_alloc(struct exec_info *execi, off_t vaddr, size_t len)
{
pg_map(PG_ALLOCATEME, vaddr, vaddr+len, &kinfo);
pg_load();
memset((char *) vaddr, 0, len);
alloc_for_vm += len;
return OK;
}
void arch_boot_proc(struct boot_image *ip, struct proc *rp)
{
multiboot_module_t *mod;
if(rp->p_nr < 0) return;
mod = bootmod(rp->p_nr);
/* Important special case: we put VM in the bootstrap pagetable
* so it can run.
*/
if(rp->p_nr == VM_PROC_NR) {
struct exec_info execi;
memset(&execi, 0, sizeof(execi));
/* exec parameters */
execi.stack_high = kinfo.user_sp;
execi.stack_size = 64 * 1024; /* not too crazy as it must be preallocated */
execi.proc_e = ip->endpoint;
execi.hdr = (char *) mod->mod_start; /* phys mem direct */
execi.filesize = execi.hdr_len = mod->mod_end - mod->mod_start;
strlcpy(execi.progname, ip->proc_name, sizeof(execi.progname));
execi.frame_len = 0;
/* callbacks for use in the kernel */
execi.copymem = libexec_copy_memcpy;
execi.clearmem = libexec_clear_memset;
execi.allocmem_prealloc_junk = libexec_pg_alloc;
execi.allocmem_prealloc_cleared = libexec_pg_alloc;
execi.allocmem_ondemand = libexec_pg_alloc;
execi.clearproc = NULL;
/* parse VM ELF binary and alloc/map it into bootstrap pagetable */
if(libexec_load_elf(&execi) != OK)
panic("VM loading failed");
/* Initialize the server stack pointer. Take it down three words
* to give startup code something to use as "argc", "argv" and "envp".
*/
arch_proc_init(rp, execi.pc, kinfo.user_sp - 3*4, ip->proc_name);
/* Free VM blob that was just copied into existence. */
add_memmap(&kinfo, mod->mod_start, mod->mod_end-mod->mod_start);
mod->mod_end = mod->mod_start = 0;
/* Remember them */
kinfo.vm_allocated_bytes = alloc_for_vm;
}
}
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