From: Tulio A M Mendes <tadryanom@hotmail.com>
Date: Tue, 10 Feb 2026 06:19:36 +0000 (-0300)
Subject: refactor: move x86 uaccess page table walking to src/arch/x86/uaccess.c
X-Git-Url: https://projects.tadryanom.me/sitemap.xml?a=commitdiff_plain;h=e7443cfc964d7f144e6efe1e780c2ee31160e299;p=AdrOS.git

refactor: move x86 uaccess page table walking to src/arch/x86/uaccess.c

The uaccess implementation used x86-specific recursive page table
mapping (0xFFFFF000/0xFFC00000) for user_range_ok, copy_from_user,
copy_to_user, and uaccess_try_recover. This is 100% arch-dependent.

- Move full x86 implementation to src/arch/x86/uaccess.c (no guards)
- Replace src/kernel/uaccess.c with weak stubs (simple memcpy-based)
- The linker picks the arch-specific version when available

Passes: make, cppcheck, QEMU smoke test.
---

diff --git a/src/arch/x86/uaccess.c b/src/arch/x86/uaccess.c
new file mode 100644
index 0000000..274448a
--- /dev/null
+++ b/src/arch/x86/uaccess.c
@@ -0,0 +1,148 @@
+#include "uaccess.h"
+
+#include "errno.h"
+#include "interrupts.h"
+#include "hal/mm.h"
+
+#include <stdint.h>
+
+static int x86_user_range_basic_ok(uintptr_t uaddr, size_t len) {
+    if (len == 0) return 1;
+    if (uaddr == 0) return 0;
+    if (uaddr >= hal_mm_kernel_virt_base()) return 0;
+    uintptr_t end = uaddr + len - 1;
+    if (end < uaddr) return 0;
+    if (end >= hal_mm_kernel_virt_base()) return 0;
+    return 1;
+}
+
+static volatile int g_uaccess_active = 0;
+static volatile int g_uaccess_faulted = 0;
+static volatile uintptr_t g_uaccess_recover_eip = 0;
+
+int uaccess_try_recover(uintptr_t fault_addr, struct registers* regs) {
+    if (!regs) return 0;
+    if (g_uaccess_active == 0) return 0;
+    if (g_uaccess_recover_eip == 0) return 0;
+
+    // Only recover faults on user addresses; kernel faults should still panic.
+    if (fault_addr >= hal_mm_kernel_virt_base()) return 0;
+
+    g_uaccess_faulted = 1;
+    regs->eip = (uint32_t)g_uaccess_recover_eip;
+    return 1;
+}
+
+static int x86_user_page_writable_user(uintptr_t vaddr) {
+    volatile uint32_t* pd = (volatile uint32_t*)0xFFFFF000U;
+    volatile uint32_t* pt_base = (volatile uint32_t*)0xFFC00000U;
+
+    uint32_t pde = pd[vaddr >> 22];
+    if (!(pde & 0x1)) return 0;
+    if (!(pde & 0x4)) return 0;
+
+    volatile uint32_t* pt = pt_base + ((vaddr >> 22) << 10);
+    uint32_t pte = pt[(vaddr >> 12) & 0x3FF];
+    if (!(pte & 0x1)) return 0;
+    if (!(pte & 0x4)) return 0;
+    if (!(pte & 0x2)) return 0;
+    return 1;
+}
+
+static int x86_user_page_present_and_user(uintptr_t vaddr) {
+    volatile uint32_t* pd = (volatile uint32_t*)0xFFFFF000U;
+    volatile uint32_t* pt_base = (volatile uint32_t*)0xFFC00000U;
+
+    uint32_t pde = pd[vaddr >> 22];
+    if (!(pde & 0x1)) return 0;
+    if (!(pde & 0x4)) return 0;
+
+    volatile uint32_t* pt = pt_base + ((vaddr >> 22) << 10);
+    uint32_t pte = pt[(vaddr >> 12) & 0x3FF];
+    if (!(pte & 0x1)) return 0;
+    if (!(pte & 0x4)) return 0;
+
+    return 1;
+}
+
+static int x86_user_range_mapped_and_user(uintptr_t uaddr, size_t len) {
+    if (!x86_user_range_basic_ok(uaddr, len)) return 0;
+    if (len == 0) return 1;
+
+    uintptr_t start = uaddr & ~(uintptr_t)0xFFF;
+    uintptr_t end = (uaddr + len - 1) & ~(uintptr_t)0xFFF;
+    for (uintptr_t va = start;; va += 0x1000) {
+        if (!x86_user_page_present_and_user(va)) return 0;
+        if (va == end) break;
+    }
+    return 1;
+}
+
+static int x86_user_range_writable_user(uintptr_t uaddr, size_t len) {
+    if (!x86_user_range_basic_ok(uaddr, len)) return 0;
+    if (len == 0) return 1;
+
+    uintptr_t start = uaddr & ~(uintptr_t)0xFFF;
+    uintptr_t end = (uaddr + len - 1) & ~(uintptr_t)0xFFF;
+    for (uintptr_t va = start;; va += 0x1000) {
+        if (!x86_user_page_writable_user(va)) return 0;
+        if (va == end) break;
+    }
+    return 1;
+}
+
+int user_range_ok(const void* user_ptr, size_t len) {
+    uintptr_t uaddr = (uintptr_t)user_ptr;
+    return x86_user_range_mapped_and_user(uaddr, len);
+}
+
+int copy_from_user(void* dst, const void* src_user, size_t len) {
+    if (len == 0) return 0;
+    if (!user_range_ok(src_user, len)) return -EFAULT;
+
+    g_uaccess_faulted = 0;
+    g_uaccess_recover_eip = (uintptr_t)&&uaccess_fault;
+    g_uaccess_active = 1;
+
+    uintptr_t up = (uintptr_t)src_user;
+    for (size_t i = 0; i < len; i++) {
+        ((uint8_t*)dst)[i] = ((const volatile uint8_t*)up)[i];
+    }
+
+    g_uaccess_active = 0;
+    g_uaccess_recover_eip = 0;
+    if (g_uaccess_faulted) return -EFAULT;
+    return 0;
+
+uaccess_fault:
+    g_uaccess_active = 0;
+    g_uaccess_faulted = 0;
+    g_uaccess_recover_eip = 0;
+    return -EFAULT;
+}
+
+int copy_to_user(void* dst_user, const void* src, size_t len) {
+    if (len == 0) return 0;
+
+    if (!x86_user_range_writable_user((uintptr_t)dst_user, len)) return -EFAULT;
+
+    g_uaccess_faulted = 0;
+    g_uaccess_recover_eip = (uintptr_t)&&uaccess_fault2;
+    g_uaccess_active = 1;
+
+    uintptr_t up = (uintptr_t)dst_user;
+    for (size_t i = 0; i < len; i++) {
+        ((volatile uint8_t*)up)[i] = ((const uint8_t*)src)[i];
+    }
+
+    g_uaccess_active = 0;
+    g_uaccess_recover_eip = 0;
+    if (g_uaccess_faulted) return -EFAULT;
+    return 0;
+
+uaccess_fault2:
+    g_uaccess_active = 0;
+    g_uaccess_faulted = 0;
+    g_uaccess_recover_eip = 0;
+    return -EFAULT;
+}
diff --git a/src/kernel/uaccess.c b/src/kernel/uaccess.c
index 84e3267..28222bd 100644
--- a/src/kernel/uaccess.c
+++ b/src/kernel/uaccess.c
@@ -2,169 +2,49 @@
 
 #include "errno.h"
 #include "interrupts.h"
-#include "hal/mm.h"
 
 #include <stdint.h>
+#include <stddef.h>
 
-#if defined(__i386__)
-
-static int x86_user_range_basic_ok(uintptr_t uaddr, size_t len) {
-    if (len == 0) return 1;
-    if (uaddr == 0) return 0;
-    if (uaddr >= hal_mm_kernel_virt_base()) return 0;
-    uintptr_t end = uaddr + len - 1;
-    if (end < uaddr) return 0;
-    if (end >= hal_mm_kernel_virt_base()) return 0;
-    return 1;
-}
-
-static volatile int g_uaccess_active = 0;
-static volatile int g_uaccess_faulted = 0;
-static volatile uintptr_t g_uaccess_recover_eip = 0;
-
+__attribute__((weak))
 int uaccess_try_recover(uintptr_t fault_addr, struct registers* regs) {
     (void)fault_addr;
-    if (!regs) return 0;
-
-#if defined(__i386__)
-    if (g_uaccess_active == 0) return 0;
-    if (g_uaccess_recover_eip == 0) return 0;
-
-    // Only recover faults on user addresses; kernel faults should still panic.
-    if (fault_addr >= hal_mm_kernel_virt_base()) return 0;
-
-    g_uaccess_faulted = 1;
-    regs->eip = (uint32_t)g_uaccess_recover_eip;
-    return 1;
-#else
+    (void)regs;
     return 0;
-#endif
-}
-
-static int x86_user_page_writable_user(uintptr_t vaddr) {
-    volatile uint32_t* pd = (volatile uint32_t*)0xFFFFF000U;
-    volatile uint32_t* pt_base = (volatile uint32_t*)0xFFC00000U;
-
-    uint32_t pde = pd[vaddr >> 22];
-    if (!(pde & 0x1)) return 0;
-    if (!(pde & 0x4)) return 0;
-
-    volatile uint32_t* pt = pt_base + ((vaddr >> 22) << 10);
-    uint32_t pte = pt[(vaddr >> 12) & 0x3FF];
-    if (!(pte & 0x1)) return 0;
-    if (!(pte & 0x4)) return 0;
-    if (!(pte & 0x2)) return 0;
-    return 1;
-}
-
-static int x86_user_page_present_and_user(uintptr_t vaddr) {
-    volatile uint32_t* pd = (volatile uint32_t*)0xFFFFF000U;
-    volatile uint32_t* pt_base = (volatile uint32_t*)0xFFC00000U;
-
-    uint32_t pde = pd[vaddr >> 22];
-    if (!(pde & 0x1)) return 0;
-    if (!(pde & 0x4)) return 0;
-
-    volatile uint32_t* pt = pt_base + ((vaddr >> 22) << 10);
-    uint32_t pte = pt[(vaddr >> 12) & 0x3FF];
-    if (!(pte & 0x1)) return 0;
-    if (!(pte & 0x4)) return 0;
-
-    return 1;
-}
-
-static int x86_user_range_mapped_and_user(uintptr_t uaddr, size_t len) {
-    if (!x86_user_range_basic_ok(uaddr, len)) return 0;
-    if (len == 0) return 1;
-
-    uintptr_t start = uaddr & ~(uintptr_t)0xFFF;
-    uintptr_t end = (uaddr + len - 1) & ~(uintptr_t)0xFFF;
-    for (uintptr_t va = start;; va += 0x1000) {
-        if (!x86_user_page_present_and_user(va)) return 0;
-        if (va == end) break;
-    }
-    return 1;
-}
-
-static int x86_user_range_writable_user(uintptr_t uaddr, size_t len) {
-    if (!x86_user_range_basic_ok(uaddr, len)) return 0;
-    if (len == 0) return 1;
-
-    uintptr_t start = uaddr & ~(uintptr_t)0xFFF;
-    uintptr_t end = (uaddr + len - 1) & ~(uintptr_t)0xFFF;
-    for (uintptr_t va = start;; va += 0x1000) {
-        if (!x86_user_page_writable_user(va)) return 0;
-        if (va == end) break;
-    }
-    return 1;
 }
-#endif
 
+__attribute__((weak))
 int user_range_ok(const void* user_ptr, size_t len) {
     uintptr_t uaddr = (uintptr_t)user_ptr;
-
-#if defined(__i386__)
-    return x86_user_range_mapped_and_user(uaddr, len);
-#else
     if (len == 0) return 1;
     if (uaddr == 0) return 0;
     uintptr_t end = uaddr + len - 1;
     if (end < uaddr) return 0;
     return 1;
-#endif
 }
 
+__attribute__((weak))
 int copy_from_user(void* dst, const void* src_user, size_t len) {
     if (len == 0) return 0;
     if (!user_range_ok(src_user, len)) return -EFAULT;
 
-    g_uaccess_faulted = 0;
-    g_uaccess_recover_eip = (uintptr_t)&&uaccess_fault;
-    g_uaccess_active = 1;
-
-    uintptr_t up = (uintptr_t)src_user;
+    const uint8_t* s = (const uint8_t*)src_user;
+    uint8_t* d = (uint8_t*)dst;
     for (size_t i = 0; i < len; i++) {
-        ((uint8_t*)dst)[i] = ((const volatile uint8_t*)up)[i];
+        d[i] = s[i];
     }
-
-    g_uaccess_active = 0;
-    g_uaccess_recover_eip = 0;
-    if (g_uaccess_faulted) return -EFAULT;
     return 0;
-
-uaccess_fault:
-    g_uaccess_active = 0;
-    g_uaccess_faulted = 0;
-    g_uaccess_recover_eip = 0;
-    return -EFAULT;
 }
 
+__attribute__((weak))
 int copy_to_user(void* dst_user, const void* src, size_t len) {
     if (len == 0) return 0;
-
-#if defined(__i386__)
-    if (!x86_user_range_writable_user((uintptr_t)dst_user, len)) return -EFAULT;
-#else
     if (!user_range_ok(dst_user, len)) return -EFAULT;
-#endif
-
-    g_uaccess_faulted = 0;
-    g_uaccess_recover_eip = (uintptr_t)&&uaccess_fault2;
-    g_uaccess_active = 1;
 
-    uintptr_t up = (uintptr_t)dst_user;
+    uint8_t* d = (uint8_t*)dst_user;
+    const uint8_t* s = (const uint8_t*)src;
     for (size_t i = 0; i < len; i++) {
-        ((volatile uint8_t*)up)[i] = ((const uint8_t*)src)[i];
+        d[i] = s[i];
     }
-
-    g_uaccess_active = 0;
-    g_uaccess_recover_eip = 0;
-    if (g_uaccess_faulted) return -EFAULT;
     return 0;
-
-uaccess_fault2:
-    g_uaccess_active = 0;
-    g_uaccess_faulted = 0;
-    g_uaccess_recover_eip = 0;
-    return -EFAULT;
 }