#include "precompiled.h"
#include "acpi.h"
#include "win/mahaf.h"
#include "lib/sysdep/cpu.h"
#include "lib/module_init.h"
#pragma pack(1)
typedef const volatile u8* PCV_u8;
typedef const volatile AcpiTable* PCV_AcpiTable;
// return 8-bit checksum of a buffer (should be 0)
static u8 ComputeChecksum(PCV_u8 buf, size_t numBytes)
{
// (can't use std::accumulate - we need 8-bit wraparound)
u8 sum = 0;
for(PCV_u8 p = buf; p < buf+numBytes; p++)
sum += *p;
return sum;
}
//-----------------------------------------------------------------------------
// exception-safe transactional map/use/unmap
//-----------------------------------------------------------------------------
// note: if the OS happens to unmap our physical memory, the Unsafe*
// functions may crash. we catch this via SEH; on Unix, we'd need handlers
// for SIGBUS and/or SIGSEGV. the code is safe in that it releases the
// mapped memory and returns an error code.
static void* SUCCEEDED = (void*)(intptr_t)1;
static void* FAILED = (void*)(intptr_t)-1;
typedef void* (*UnsafeFunction)(PCV_u8 mem, size_t numBytes, void* arg);
static inline void* CallWithSafetyBlanket(UnsafeFunction func, PCV_u8 mem, size_t numBytes, void* arg)
{
#if MSC_VERSION
__try
{
return func(mem, numBytes, arg);
}
__except(1)
{
return FAILED;
}
#else
return func(mem, numBytes, arg);
#endif
}
static void* TransactPhysicalMemory(u64 physicalAddress, size_t numBytes, UnsafeFunction func, void* arg = 0)
{
PCV_u8 mem = (PCV_u8)mahaf_MapPhysicalMemory(physicalAddress, numBytes);
if(!mem)
return FAILED;
void* ret = CallWithSafetyBlanket(func, mem, numBytes, arg);
mahaf_UnmapPhysicalMemory((volatile void*)mem);
return ret;
}
//-----------------------------------------------------------------------------
// Root System Descriptor Pointer
//-----------------------------------------------------------------------------
struct BiosDataArea
{
u16 serialBase[4];
u16 parallelBase[3];
u16 ebdaSegment;
};
typedef const volatile BiosDataArea* PCV_BiosDataArea;
static void* UnsafeReadEbdaPhysicalAddress(PCV_u8 mem, size_t numBytes, void* UNUSED(arg))
{
debug_assert(numBytes >= sizeof(BiosDataArea));
PCV_BiosDataArea bda = (PCV_BiosDataArea)mem;
const uintptr_t ebdaPhysicalAddress = ((uintptr_t)bda->ebdaSegment) * 16;
return (void*)ebdaPhysicalAddress;
}
struct RSDP
{
char signature[8]; // "RSD PTR "
u8 checksum; // sum of this struct = 0
char oemId[6];
u8 revision; // 0 for 1.0, 2 for 2.0
u32 rsdtPhysicalAddress;
};
typedef const volatile RSDP* PCV_RSDP;
static const size_t RSDP_ALIGNMENT = 16;
static void* UnsafeLocateAndRetrieveRsdp(PCV_u8 buf, size_t numBytes, void* arg)
{
debug_assert(numBytes >= sizeof(RSDP));
for(PCV_u8 p = buf; p < buf+numBytes; p += RSDP_ALIGNMENT)
{
RSDP* prsdp = (RSDP*)p;
if(memcmp(prsdp->signature, "RSD PTR ", 8) != 0)
continue;
if(ComputeChecksum(p, sizeof(RSDP)) != 0)
continue;
*(RSDP*)arg = *prsdp;
return SUCCEEDED;
}
return FAILED;
}
static bool RetrieveRsdp(RSDP& rsdp)
{
// See ACPIspec30b, section 5.2.5.1:
// RSDP is either in the first KIB of the extended BIOS data area,
void* ret = TransactPhysicalMemory(0x400, 0x100, UnsafeReadEbdaPhysicalAddress);
if(ret != FAILED)
{
const uintptr_t ebdaPhysicalAddress = (uintptr_t)ret;
ret = TransactPhysicalMemory(ebdaPhysicalAddress, 0x400, UnsafeLocateAndRetrieveRsdp, &rsdp);
if(ret == SUCCEEDED)
return true;
}
// or in read-only BIOS memory.
ret = TransactPhysicalMemory(0xE0000, 0x20000, UnsafeLocateAndRetrieveRsdp, &rsdp);
if(ret == SUCCEEDED)
return true;
return false; // not found
}
//-----------------------------------------------------------------------------
// table retrieval
//-----------------------------------------------------------------------------
static inline void* UnsafeAllocateCopyOfTable(PCV_u8 mem, size_t numBytes, void* arg)
{
debug_assert(numBytes >= sizeof(AcpiTable));
PCV_AcpiTable table = (PCV_AcpiTable)mem;
const size_t tableSize = table->size;
// physical memory window is smaller than the table
// (caller will map a larger window and call us again)
if(numBytes < tableSize)
{
*(size_t*)arg = tableSize;
return 0;
}
PCV_u8 copy = (PCV_u8)malloc(tableSize);
if(!copy)
return FAILED;
cpu_memcpy((void*)copy, (const void*)mem, tableSize);
return (void*)copy;
}
// caller is responsible for verifying the table is valid and using
// DeallocateTable to free it.
static const AcpiTable* AllocateCopyOfTable(u64 physicalAddress)
{
// ACPI table sizes are not known until they've been mapped. since that
// is slow, we don't always want to do it twice. the solution is to map
// enough for a typical table; if that is too small, realloc and map again.
static const size_t initialSize = 4*KiB;
size_t actualSize = 0;
void* ret = TransactPhysicalMemory(physicalAddress, initialSize, UnsafeAllocateCopyOfTable, &actualSize);
// initialSize was too small; actualSize has been set
if(ret == 0)
ret = TransactPhysicalMemory(physicalAddress, actualSize, UnsafeAllocateCopyOfTable);
// *either* of the above calls failed to allocate memory
if(ret == FAILED)
return 0;
return (const AcpiTable*)ret;
}
template<typename T>
static void DeallocateTable(const T* table)
{
free((void*)table);
}
static bool VerifyTable(const AcpiTable* table, const char* signature = 0)
{
if(!table)
return false;
// caller knowns the signature; make sure it matches
if(signature)
{
if(memcmp(table->signature, signature, 4) != 0)
return false;
}
// no specific signature is called for; just make sure it's 4 letters
else
{
for(int i = 0; i < 4; i++)
{
if(!isalpha(table->signature[i]))
return false;
}
}
// must be at least as large as the common header
if(table->size < sizeof(AcpiTable))
return false;
// checksum of table must be 0
// .. AMIBIOS OEMB table has an incorrect checksum (off-by-one),
// so don't complain about any OEM tables (ignored anyway).
const bool isOemTable = (memcmp(table->signature, "OEM", 3) == 0);
if(ComputeChecksum((PCV_u8)table, table->size) != 0 && !isOemTable)
return false;
return true;
}
static const AcpiTable* GetTable(u64 physicalAddress, const char* signature = 0)
{
const AcpiTable* table = AllocateCopyOfTable(physicalAddress);
if(VerifyTable(table, signature))
return table;
else
{
DeallocateTable(table);
return 0;
}
}
//-----------------------------------------------------------------------------
// table storage
//-----------------------------------------------------------------------------
// Root System Descriptor Table
struct RSDT
{
AcpiTable header;
u32 tables[1];
};
// avoid std::map et al. because we may be called before _cinit
static const AcpiTable** tables;
static int numTables;
static bool LatchAllTables()
{
RSDP rsdp;
if(!RetrieveRsdp(rsdp))
return false;
const RSDT* rsdt = (const RSDT*)GetTable(rsdp.rsdtPhysicalAddress, "RSDT");
if(!rsdt)
return false;
numTables = (rsdt->header.size -sizeof(AcpiTable)) / sizeof(rsdt->tables[0]);
debug_assert(numTables > 0);
tables = new const AcpiTable*[numTables];
for(int i = 0; i < numTables; i++)
tables[i] = GetTable(rsdt->tables[i]);
DeallocateTable(rsdt);
return true;
}
static void FreeAllTables()
{
if(tables)
{
for(int i = 0; i < numTables; i++)
DeallocateTable(tables[i]);
delete[] tables;
}
}
const AcpiTable* acpi_GetTable(const char* signature)
{
// (typically only a few tables, linear search is OK)
for(int i = 0; i < numTables; i++)
{
const AcpiTable* table = tables[i];
if(!table)
continue; // skip invalid tables, e.g. OEM (see above)
if(strncmp(table->signature, signature, 4) == 0)
return table;
}
return 0;
}
//-----------------------------------------------------------------------------
static ModuleInitState initState;
bool acpi_Init()
{
if(!ModuleShouldInitialize(&initState))
return true;
if(!mahaf_Init())
goto fail;
if(!LatchAllTables())
goto fail;
return true;
fail:
ModuleSetError(&initState);
return false;
}
void acpi_Shutdown()
{
if(!ModuleShouldShutdown(&initState))
return;
FreeAllTables();
mahaf_Shutdown();
}