kernel: Refactor AHCI I/O path, enhance memory allocators, and cleanup obsolete script

- Removed unused `build_gcc.sh` script.
- Namespaced CPU feature flags under `NeOS` and transitioned from enum to unnamed enum for scoping.
- Renamed `drv_std_input_output` to `drv_std_input_output_ahci` for clarity.
- Improved AHCI driver documentation and added zeroing for read buffers.
- Added optional `pad` parameter to memory allocators: `mm_alloc_bitmap`, `mm_new_heap`, `PageMgr::Request`, etc.
- Updated bitmap allocator to correctly handle and align with padded sizes.
- Added `fPad` field to memory header block.
- Fixed `ATA-DMA` mode comment, corrected PRD usage and logic.
- Improved code documentation and formatting in `UserProcessScheduler`, `PageMgr`, and related components.
- Enhanced safety in process memory cleanup (e.g., `StackReserve` cleanup).

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>

4 files changed, 129 insertions, 88 deletions

diff --git a/dev/kernel/HALKit/AMD64/CPUID.h b/dev/kernel/HALKit/AMD64/CPUID.h
index 7f04ac27..6ea84106 100644
--- a/dev/kernel/HALKit/AMD64/CPUID.h
+++ b/dev/kernel/HALKit/AMD64/CPUID.h
@@ -15,72 +15,73 @@
 
 #include <NewKit/Defines.h>
 
-enum CPUFeatureEnum
-{
-	kCPUFeatureSSE3		  = 1 << 0,
-	kCPUFeaturePCLMUL	  = 1 << 1,
-	kCPUFeatureDTES64	  = 1 << 2,
-	kCPUFeatureMONITOR	  = 1 << 3,
-	kCPUFeatureDS_CPL	  = 1 << 4,
-	kCPUFeatureVMX		  = 1 << 5,
-	kCPUFeatureSMX		  = 1 << 6,
-	kCPUFeatureEST		  = 1 << 7,
-	kCPUFeatureTM2		  = 1 << 8,
-	kCPUFeatureSSSE3	  = 1 << 9,
-	kCPUFeatureCID		  = 1 << 10,
-	kCPUFeatureSDBG		  = 1 << 11,
-	kCPUFeatureFMA		  = 1 << 12,
-	kCPUFeatureCX16		  = 1 << 13,
-	kCPUFeatureXTPR		  = 1 << 14,
-	kCPUFeaturePDCM		  = 1 << 15,
-	kCPUFeaturePCID		  = 1 << 17,
-	kCPUFeatureDCA		  = 1 << 18,
-	kCPUFeatureSSE4_1	  = 1 << 19,
-	kCPUFeatureSSE4_2	  = 1 << 20,
-	kCPUFeatureX2APIC	  = 1 << 21,
-	kCPUFeatureMOVBE	  = 1 << 22,
-	kCPUFeaturePOP3C	  = 1 << 23,
-	kCPUFeatureECXTSC	  = 1 << 24,
-	kCPUFeatureAES		  = 1 << 25,
-	kCPUFeatureXSAVE	  = 1 << 26,
-	kCPUFeatureOSXSAVE	  = 1 << 27,
-	kCPUFeatureAVX		  = 1 << 28,
-	kCPUFeatureF16C		  = 1 << 29,
-	kCPUFeatureRDRAND	  = 1 << 30,
-	kCPUFeatureHYPERVISOR = 1 << 31,
-	kCPUFeatureFPU		  = 1 << 0,
-	kCPUFeatureVME		  = 1 << 1,
-	kCPUFeatureDE		  = 1 << 2,
-	kCPUFeaturePSE		  = 1 << 3,
-	kCPUFeatureEDXTSC	  = 1 << 4,
-	kCPUFeatureMSR		  = 1 << 5,
-	kCPUFeaturePAE		  = 1 << 6,
-	kCPUFeatureMCE		  = 1 << 7,
-	kCPUFeatureCX8		  = 1 << 8,
-	kCPUFeatureAPIC		  = 1 << 9,
-	kCPUFeatureSEP		  = 1 << 11,
-	kCPUFeatureMTRR		  = 1 << 12,
-	kCPUFeaturePGE		  = 1 << 13,
-	kCPUFeatureMCA		  = 1 << 14,
-	kCPUFeatureCMOV		  = 1 << 15,
-	kCPUFeaturePAT		  = 1 << 16,
-	kCPUFeaturePSE36	  = 1 << 17,
-	kCPUFeaturePSN		  = 1 << 18,
-	kCPUFeatureCLFLUSH	  = 1 << 19,
-	kCPUFeatureDS		  = 1 << 21,
-	kCPUFeatureACPI		  = 1 << 22,
-	kCPUFeatureMMX		  = 1 << 23,
-	kCPUFeatureFXSR		  = 1 << 24,
-	kCPUFeatureSSE		  = 1 << 25,
-	kCPUFeatureSSE2		  = 1 << 26,
-	kCPUFeatureSS		  = 1 << 27,
-	kCPUFeatureHTT		  = 1 << 28,
-	kCPUFeatureTM		  = 1 << 29,
-	kCPUFeatureIA64		  = 1 << 30,
-	kCPUFeaturePBE		  = 1 << 31
-};
-
 namespace NeOS
 {
+
+	enum
+	{
+		kCPUFeatureSSE3		  = 1 << 0,
+		kCPUFeaturePCLMUL	  = 1 << 1,
+		kCPUFeatureDTES64	  = 1 << 2,
+		kCPUFeatureMONITOR	  = 1 << 3,
+		kCPUFeatureDS_CPL	  = 1 << 4,
+		kCPUFeatureVMX		  = 1 << 5,
+		kCPUFeatureSMX		  = 1 << 6,
+		kCPUFeatureEST		  = 1 << 7,
+		kCPUFeatureTM2		  = 1 << 8,
+		kCPUFeatureSSSE3	  = 1 << 9,
+		kCPUFeatureCID		  = 1 << 10,
+		kCPUFeatureSDBG		  = 1 << 11,
+		kCPUFeatureFMA		  = 1 << 12,
+		kCPUFeatureCX16		  = 1 << 13,
+		kCPUFeatureXTPR		  = 1 << 14,
+		kCPUFeaturePDCM		  = 1 << 15,
+		kCPUFeaturePCID		  = 1 << 17,
+		kCPUFeatureDCA		  = 1 << 18,
+		kCPUFeatureSSE4_1	  = 1 << 19,
+		kCPUFeatureSSE4_2	  = 1 << 20,
+		kCPUFeatureX2APIC	  = 1 << 21,
+		kCPUFeatureMOVBE	  = 1 << 22,
+		kCPUFeaturePOP3C	  = 1 << 23,
+		kCPUFeatureECXTSC	  = 1 << 24,
+		kCPUFeatureAES		  = 1 << 25,
+		kCPUFeatureXSAVE	  = 1 << 26,
+		kCPUFeatureOSXSAVE	  = 1 << 27,
+		kCPUFeatureAVX		  = 1 << 28,
+		kCPUFeatureF16C		  = 1 << 29,
+		kCPUFeatureRDRAND	  = 1 << 30,
+		kCPUFeatureHYPERVISOR = 1 << 31,
+		kCPUFeatureFPU		  = 1 << 0,
+		kCPUFeatureVME		  = 1 << 1,
+		kCPUFeatureDE		  = 1 << 2,
+		kCPUFeaturePSE		  = 1 << 3,
+		kCPUFeatureEDXTSC	  = 1 << 4,
+		kCPUFeatureMSR		  = 1 << 5,
+		kCPUFeaturePAE		  = 1 << 6,
+		kCPUFeatureMCE		  = 1 << 7,
+		kCPUFeatureCX8		  = 1 << 8,
+		kCPUFeatureAPIC		  = 1 << 9,
+		kCPUFeatureSEP		  = 1 << 11,
+		kCPUFeatureMTRR		  = 1 << 12,
+		kCPUFeaturePGE		  = 1 << 13,
+		kCPUFeatureMCA		  = 1 << 14,
+		kCPUFeatureCMOV		  = 1 << 15,
+		kCPUFeaturePAT		  = 1 << 16,
+		kCPUFeaturePSE36	  = 1 << 17,
+		kCPUFeaturePSN		  = 1 << 18,
+		kCPUFeatureCLFLUSH	  = 1 << 19,
+		kCPUFeatureDS		  = 1 << 21,
+		kCPUFeatureACPI		  = 1 << 22,
+		kCPUFeatureMMX		  = 1 << 23,
+		kCPUFeatureFXSR		  = 1 << 24,
+		kCPUFeatureSSE		  = 1 << 25,
+		kCPUFeatureSSE2		  = 1 << 26,
+		kCPUFeatureSS		  = 1 << 27,
+		kCPUFeatureHTT		  = 1 << 28,
+		kCPUFeatureTM		  = 1 << 29,
+		kCPUFeatureIA64		  = 1 << 30,
+		kCPUFeaturePBE		  = 1 << 31
+	};
+
 	typedef Int64 CPUID;
 } // namespace NeOS
diff --git a/dev/kernel/HALKit/AMD64/Paging.h b/dev/kernel/HALKit/AMD64/Paging.h
index 4e2ac1b1..09b6ade3 100644
--- a/dev/kernel/HALKit/AMD64/Paging.h
+++ b/dev/kernel/HALKit/AMD64/Paging.h
@@ -88,7 +88,7 @@ namespace NeOS::HAL
 		NE_PTE* ALIGN(kPageAlign) fEntries[kPageMax];
 	};
 
-	auto mm_alloc_bitmap(Boolean wr, Boolean user, SizeT size, Bool is_page) -> VoidPtr;
+	auto mm_alloc_bitmap(Boolean wr, Boolean user, SizeT size, Bool is_page, const SizeT pad = 0) -> VoidPtr;
 	auto mm_free_bitmap(VoidPtr page_ptr) -> Bool;
 } // namespace NeOS::HAL
 
diff --git a/dev/kernel/HALKit/AMD64/Storage/AHCI+Generic.cc b/dev/kernel/HALKit/AMD64/Storage/AHCI+Generic.cc
index bd5c86f4..b1584c80 100644
--- a/dev/kernel/HALKit/AMD64/Storage/AHCI+Generic.cc
+++ b/dev/kernel/HALKit/AMD64/Storage/AHCI+Generic.cc
@@ -63,7 +63,7 @@ STATIC Char	   kCurrentDiskModel[50] = {"UNKNOWN AHCI DRIVE"};
 STATIC UInt16  kSATAPortsImplemented = 0U;
 
 template <BOOL Write, BOOL CommandOrCTRL, BOOL Identify>
-STATIC Void drv_std_input_output(UInt64 lba, UInt8* buffer, SizeT sector_sz, SizeT size_buffer) noexcept;
+STATIC Void drv_std_input_output_ahci(UInt64 lba, UInt8* buffer, SizeT sector_sz, SizeT size_buffer) noexcept;
 
 STATIC Int32 drv_find_cmd_slot(HbaPort* port) noexcept;
 
@@ -73,21 +73,29 @@ STATIC Void drv_compute_disk_ahci() noexcept
 {
 	kSATASectorCount = 0UL;
 
+	/// Normally 512 bytes, but add an additional 512 bytes to make 1 KIB.
 	const UInt16 kSzIdent = kib_cast(1);
 
+	/// Push it to the stack
 	UInt8 identify_data[kSzIdent] = {0};
 
 	rt_set_memory(identify_data, 0, kSzIdent);
 
-	drv_std_input_output<NO, YES, YES>(0, identify_data, kAHCISectorSize, kSzIdent);
+	/// Send AHCI command.
+	drv_std_input_output_ahci<NO, YES, YES>(0, identify_data, kAHCISectorSize, kSzIdent);
 
+	/// Extract 28-bit LBA.
 	kSATASectorCount = (identify_data[61] << 16) | identify_data[60];
 
+	/// Show what we got.
 	kout << "Disk Model: " << kCurrentDiskModel << kendl;
 	kout << "Disk Size: " << number(drv_get_size()) << kendl;
 	kout << "Disk Sector Count: " << number(kSATASectorCount) << kendl;
 }
 
+/// @brief Finds a command slot for a HBA port.
+/// @param port The port to search on.
+/// @return The slot, or ~0.
 STATIC Int32 drv_find_cmd_slot(HbaPort* port) noexcept
 {
 	UInt32 slots = (port->Sact | port->Ci);
@@ -103,8 +111,13 @@ STATIC Int32 drv_find_cmd_slot(HbaPort* port) noexcept
 	return ~0;
 }
 
+/// @brief Send an AHCI command, according to the template parameters.
+/// @param lba Logical Block Address to look for.
+/// @param buffer The data buffer to transfer.
+/// @param sector_sz The disk's sector size (unused)
+/// @param size_buffer The size of the **buffer** parameter.
 template <BOOL Write, BOOL CommandOrCTRL, BOOL Identify>
-STATIC Void drv_std_input_output(UInt64 lba, UInt8* buffer, SizeT sector_sz, SizeT size_buffer) noexcept
+STATIC Void drv_std_input_output_ahci(UInt64 lba, UInt8* buffer, SizeT sector_sz, SizeT size_buffer) noexcept
 {
 	UIntPtr slot = 0UL;
 
@@ -113,6 +126,12 @@ STATIC Void drv_std_input_output(UInt64 lba, UInt8* buffer, SizeT sector_sz, Siz
 	if (slot == ~0)
 		return;
 
+	if (!Write)
+	{
+		// Zero-memory the buffer field.
+		rt_set_memory(buffer, 0, size_buffer);
+	}
+
 	volatile HbaCmdHeader* command_header = ((HbaCmdHeader*)(((UInt64)kSATAHba->Ports[kSATAIndex].Clb)));
 
 	command_header += slot;
@@ -310,6 +329,8 @@ STATIC Bool drv_std_init_ahci(UInt16& pi, BOOL& atapi)
 	return NO;
 }
 
+/// @brief Checks if an AHCI device is detected.
+/// @return Either if detected, or not found.
 Bool drv_std_detected_ahci()
 {
 	return kSATADev.DeviceId() != (UShort)PCI::PciConfigKind::Invalid && kSATADev.Bar(kSATABar5) != 0;
@@ -317,6 +338,7 @@ Bool drv_std_detected_ahci()
 
 namespace NeOS
 {
+	/// @brief Initialize an AHCI device (StorageKit)
 	UInt16 sk_init_ahci_device(BOOL atapi)
 	{
 		UInt16 pi = 0;
@@ -327,6 +349,7 @@ namespace NeOS
 		return pi;
 	}
 
+	/// @brief Implementation details namespace.
 	namespace Detail
 	{
 		/// @brief Read AHCI device.
@@ -344,7 +367,7 @@ namespace NeOS
 			if (!disk)
 				return;
 
-			drv_std_input_output<NO, YES, NO>(disk->fPacket.fPacketLba, (UInt8*)disk->fPacket.fPacketContent, kAHCISectorSize, disk->fPacket.fPacketSize);
+			drv_std_input_output_ahci<NO, YES, NO>(disk->fPacket.fPacketLba, (UInt8*)disk->fPacket.fPacketContent, kAHCISectorSize, disk->fPacket.fPacketSize);
 		}
 
 		/// @brief Write AHCI device.
@@ -362,10 +385,13 @@ namespace NeOS
 			if (!disk)
 				return;
 
-			drv_std_input_output<YES, YES, NO>(disk->fPacket.fPacketLba, (UInt8*)disk->fPacket.fPacketContent, kAHCISectorSize, disk->fPacket.fPacketSize);
+			drv_std_input_output_ahci<YES, YES, NO>(disk->fPacket.fPacketLba, (UInt8*)disk->fPacket.fPacketContent, kAHCISectorSize, disk->fPacket.fPacketSize);
 		}
 	} // namespace Detail
 
+	/// @brief Acquires a new AHCI device with drv_index in mind.
+	/// @param drv_index The drive index to assign.
+	/// @return A wrapped device interface if successful, or error code.
 	ErrorOr<AHCIDeviceInterface> sk_acquire_ahci_device(Int32 drv_index)
 	{
 		if (!drv_std_detected_ahci())
@@ -382,16 +408,24 @@ namespace NeOS
 	}
 } // namespace NeOS
 
+// ================================================================================================
+
+//
+//	This applies only if we compile with AHCI as a default disk driver.
+//
+
+// ================================================================================================
+
 #ifdef __AHCI__
 
 Void drv_std_write(UInt64 lba, Char* buffer, SizeT sector_sz, SizeT size_buffer)
 {
-	drv_std_input_output<YES, YES, NO>(lba, (UInt8*)buffer, sector_sz, size_buffer);
+	drv_std_input_output_ahci<YES, YES, NO>(lba, (UInt8*)buffer, sector_sz, size_buffer);
 }
 
 Void drv_std_read(UInt64 lba, Char* buffer, SizeT sector_sz, SizeT size_buffer)
 {
-	drv_std_input_output<NO, YES, NO>(lba, (UInt8*)buffer, sector_sz, size_buffer);
+	drv_std_input_output_ahci<NO, YES, NO>(lba, (UInt8*)buffer, sector_sz, size_buffer);
 }
 
 Bool drv_std_init(UInt16& pi)
diff --git a/dev/kernel/HALKit/AMD64/Storage/DMA+Generic.cc b/dev/kernel/HALKit/AMD64/Storage/DMA+Generic.cc
index 0a03dafc..9624ea5b 100644
--- a/dev/kernel/HALKit/AMD64/Storage/DMA+Generic.cc
+++ b/dev/kernel/HALKit/AMD64/Storage/DMA+Generic.cc
@@ -7,7 +7,7 @@
 /**
  * @file ATA-PIO.cc
  * @author Amlal EL Mahrouss (amlal@nekernel.org)
- * @brief ATA driver (PIO mode).
+ * @brief ATA driver (DMA mode).
  * @version 0.1
  * @date 2024-02-02
  *
@@ -131,17 +131,15 @@ Boolean drv_std_init(UInt16 Bus, UInt8 Drive, UInt16& OutBus, UInt8& OutMaster)
 	return NO;
 }
 
-namespace Detail
+namespace NeOS::Detail
 {
-	using namespace NeOS;
-
 	struct PRDEntry
 	{
 		UInt32 mAddress;
 		UInt16 mByteCount;
 		UInt16 mFlags;
 	};
-} // namespace Detail
+} // namespace NeOS::Detail
 
 static UIntPtr kReadAddr  = mib_cast(2);
 static UIntPtr kWriteAddr = mib_cast(4);
@@ -151,7 +149,7 @@ Void drv_std_read(UInt64 Lba, UInt16 IO, UInt8 Master, Char* Buf, SizeT SectorSz
 	Lba /= SectorSz;
 
 	if (Size > kib_cast(64))
-		ke_panic(RUNTIME_CHECK_FAILED, "ATA-DMA only supports < 64kb DMA transfers.");
+		return;
 
 	UInt8 Command = ((!Master) ? 0xE0 : 0xF0);
 
@@ -168,7 +166,7 @@ Void drv_std_read(UInt64 Lba, UInt16 IO, UInt8 Master, Char* Buf, SizeT SectorSz
 	rt_out8(IO + ATA_REG_LBA2, (Lba) >> 16);
 	rt_out8(IO + ATA_REG_LBA3, (Lba) >> 24);
 
-	Detail::PRDEntry* prd = (Detail::PRDEntry*)(kATADevice.Bar(0x20) + 4); // The PRDEntry is not correct.
+	NeOS::Detail::PRDEntry* prd = (NeOS::Detail::PRDEntry*)(kATADevice.Bar(0x20) + 4); // The PRDEntry is not correct.
 
 	prd->mAddress	= (UInt32)(UIntPtr)kReadAddr;
 	prd->mByteCount = Size - 1;
@@ -196,7 +194,7 @@ Void drv_std_write(UInt64 Lba, UInt16 IO, UInt8 Master, Char* Buf, SizeT SectorS
 	Lba /= SectorSz;
 
 	if (Size > kib_cast(64))
-		ke_panic(RUNTIME_CHECK_FAILED, "ATA-DMA only supports < 64kb DMA transfers.");
+		return;
 
 	UInt8 Command = ((!Master) ? 0xE0 : 0xF0);
 
@@ -211,10 +209,11 @@ Void drv_std_write(UInt64 Lba, UInt16 IO, UInt8 Master, Char* Buf, SizeT SectorS
 	rt_out8(IO + ATA_REG_LBA2, (Lba) >> 16);
 	rt_out8(IO + ATA_REG_LBA3, (Lba) >> 24);
 
-	Detail::PRDEntry* prd = (Detail::PRDEntry*)(kATADevice.Bar(0x20) + 4);
-	prd->mAddress		  = (UInt32)(UIntPtr)kWriteAddr;
-	prd->mByteCount		  = Size - 1;
-	prd->mFlags			  = 0x8000;
+	NeOS::Detail::PRDEntry* prd = (NeOS::Detail::PRDEntry*)(kATADevice.Bar(0x20) + 4);
+
+	prd->mAddress	= (UInt32)(UIntPtr)kWriteAddr;
+	prd->mByteCount = Size - 1;
+	prd->mFlags		= 0x8000;
 
 	rt_out32(kATADevice.Bar(0x20) + 0x04, (UInt32)(UIntPtr)prd);
 	rt_out8(kATADevice.Bar(0x20) + ATA_REG_COMMAND, ATA_CMD_WRITE_DMA);
@@ -230,21 +229,28 @@ Void drv_std_write(UInt64 Lba, UInt16 IO, UInt8 Master, Char* Buf, SizeT SectorS
 	prd = nullptr;
 }
 
-/// @brief is ATA detected?
+/***********************************************************************************/
+/// @brief Is ATA detected?
+/***********************************************************************************/
 Boolean drv_std_detected(Void)
 {
 	return kATADetected;
 }
 
+/***********************************************************************************/
 /***
-	@brief Getter, gets the number of sectors inside the drive.
+	@brief Gets the number of sectors inside the drive.
+	@return Number of sectors, or zero.
 */
+/***********************************************************************************/
 NeOS::SizeT drv_get_sector_count()
 {
 	return (kATAData[61] << 16) | kATAData[60];
 }
 
-/// @brief Get the drive size.
+/***********************************************************************************/
+/// @brief Get the size of the current drive.
+/***********************************************************************************/
 NeOS::SizeT drv_get_size()
 {
 	return (drv_get_sector_count()) * kATASectorSize;