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#include <efi.h>
#include <efilib.h>
EFI_STATUS
GetVariableAttr(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner,
UINT32 *attributes)
{
EFI_STATUS efi_status;
*len = 0;
efi_status = uefi_call_wrapper(RT->GetVariable, 5, var, &owner,
NULL, len, NULL);
if (efi_status != EFI_BUFFER_TOO_SMALL)
return efi_status;
*data = AllocateZeroPool(*len);
if (!*data)
return EFI_OUT_OF_RESOURCES;
efi_status = uefi_call_wrapper(RT->GetVariable, 5, var, &owner,
attributes, len, *data);
if (efi_status != EFI_SUCCESS) {
FreePool(*data);
*data = NULL;
}
return efi_status;
}
EFI_STATUS
GetVariable(CHAR16 *var, UINT8 **data, UINTN *len, EFI_GUID owner)
{
return GetVariableAttr(var, data, len, owner, NULL);
}
EFI_GUID DUMMY_GUID =
{0x55aad538, 0x8f82, 0x4e2a, {0xa4,0xf0,0xbe, 0x59, 0x13, 0xb6, 0x5f, 0x1e}};
#if defined(__clang__)
# define _OPTNONE __attribute__((optnone))
#else
# define _OPTNONE __attribute__((__optimize__("0")))
#endif
static _OPTNONE void
DebugHook(void)
{
EFI_GUID guid = DUMMY_GUID;
UINT8 *data = NULL;
UINTN dataSize = 0;
EFI_STATUS efi_status;
register volatile unsigned long long x = 0;
extern char _text, _data;
if (x)
return;
efi_status = GetVariable(L"DUMMY_DEBUG", &data, &dataSize, guid);
if (EFI_ERROR(efi_status)) {
return;
}
Print(L"add-symbol-file /usr/lib/debug/boot/efi/debughook.debug "
L"0x%08x -s .data 0x%08x\n", &_text, &_data);
Print(L"Pausing for debugger attachment.\n");
Print(L"To disable this, remove the EFI variable DUMMY_DEBUG-%g .\n",
&guid);
x = 1;
while (x++) {
/* Make this so it can't /totally/ DoS us. */
#if defined(__x86_64__) || defined(__i386__) || defined(__i686__)
if (x > 4294967294ULL)
break;
__asm__ __volatile__("pause");
#elif defined(__aarch64__)
if (x > 1000)
break;
__asm__ __volatile__("wfi");
#else
if (x > 12000)
break;
uefi_call_wrapper(BS->Stall, 1, 5000);
#endif
}
x = 1;
}
EFI_STATUS
efi_main (EFI_HANDLE image, EFI_SYSTEM_TABLE *systab)
{
InitializeLib(image, systab);
DebugHook();
return EFI_SUCCESS;
}
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