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Kernel: Pass current cpu index as a GDT limit

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I had no idea LSL was an instruction. This cleans up code to get the
current cpu by a lot and does not require extra segment usage :D
This commit is contained in:
Bananymous
2026-05-02 18:10:10 +03:00
parent d49d260a09
commit 3874e0ed1e
9 changed files with 23 additions and 42 deletions
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11
userspace/libraries/LibC/sched.cpp
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@@ -27,12 +27,7 @@ int sched_getcpu(void)
{
if (g_shared_page == nullptr)
return -1;
uint8_t cpu;
#if defined(__x86_64__)
asm volatile("movb %%gs:0, %0" : "=r"(cpu));
#elif defined(__i686__)
asm volatile("movb %%fs:0, %0" : "=q"(cpu));
#endif
return cpu;
uint16_t limit;
asm volatile("lsl %1, %0" : "=r"(limit) : "r"(g_shared_page->gdt_cpu_offset));
return limit;
}

10
userspace/libraries/LibC/time.cpp
View File

@@ -30,13 +30,9 @@ int clock_gettime(clockid_t clock_id, struct timespec* tp)
const auto get_cpu =
[]() -> uint8_t {
uint8_t cpu;
#if defined(__x86_64__)
asm volatile("movb %%gs:0, %0" : "=r"(cpu));
#elif defined(__i686__)
asm volatile("movb %%fs:0, %0" : "=q"(cpu));
#endif
return cpu;
uint16_t limit;
asm volatile("lsl %1, %0" : "=r"(limit) : "r"(g_shared_page->gdt_cpu_offset));
return limit;
};
for (;;)