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create and switch to new stack

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This commit is contained in:
uosfz 2025-05-28 21:39:43 +02:00
parent 45d6fea05b
commit 908b5d1d5f
Signed by: uosfz
SSH key fingerprint: SHA256:FlktuluyhTQg3jHZNLKwxOOC5hbfrUXM0tz3IA3lGJo
1 changed files with 19 additions and 1 deletions
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20
src/x86_64/paging.c
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@ -1,5 +1,6 @@
#include "std.h"
#include "ram.h"
#include "x86_64/address.h"
#include "x86_64/asm.h"
#include "x86_64/paging.h"
@ -494,13 +495,21 @@ void pt_create_minimal(void) {
// 16 GiB identity map with hugepages starting at low end of upper half of AS
unsigned int npages_in_gb = 1ull << 18;
unsigned int npages_idmap = 16 * npages_in_gb;
struct vpn vpn_idmap_start = vpn_from_aligned_va(va_from_value(1ull << 47));
pt_map_range(vpn_idmap_start,
ppn_from_pagenum(0),
16 * npages_in_gb,
npages_idmap,
true, true, false,
new_cr3);
// new stack with 4 GiB size and guard pages around
// TODO one stack for each core
struct vpn stack_virt = vpn_from_pagenum(vpn_to_pagenum(vpn_idmap_start) + npages_idmap + 1);
struct ppn stack_phys;
ASSERT(ram_alloc_frame_zeroed(&stack_phys, RAM_PAGE_NORMAL));
pt_map_single(stack_virt, stack_phys, true, true, false, new_cr3);
#ifdef PT_CREATE_DEBUG
uint64_t value = pa_to_value(pa_from_ppn(new_cr3));
printf("new cr3: %p\n", value);
@ -529,9 +538,18 @@ void pt_create_minimal(void) {
set_cr3(value);
set_identity_mapping(vpn_idmap_start);
// stack switch
// it doesn't really make sense to copy stack contents because rbp and pointers
// to local variables will point to the wrong location.
// this means we won't leave this function for now.
uint64_t new_sp = va_to_canonical(va_from_vpn(stack_virt)) + 4096;
__asm__("mov %0,%%rsp" ::"r"(new_sp));
#ifdef PT_CREATE_DEBUG
printf("hello from new page table!\n");
#endif
PANIC("end of pt_create_minimal");
}
// --- iterators ---