cpuid.c File Reference

This application will show some information about the CPU. More...

#include <Uefi.h>
#include <Library/UefiLib.h>
#include <UEFIStarter/core.h>

Data Structures
struct	idt_reg_t
	data type for interrupt descriptor table metadata More...

Macros
#define	CI(NAME, REGISTER, BIT)   Print(L ## #NAME ": %d\n",(REGISTER&1<<BIT)>0)
	helper macro to quickly output a CPUID flag More...

Functions
void	cpuid ()
	Prints the CPU's vendor ID and a few of the capability flags.
UINT64	rdmsr (UINT64 rcx)
	Reads a CPU's model-specific register. More...
void	read_msrs ()
	Prints a selection of model-specific CPU registers. More...
void	handler ()
	Interrupt handler, this will be registered by test_idt() and should get called when signalling the interrupt there. More...
void	write_idt_entry_address (void *entry_base, void *func)
	Writes an interrupt handler address into the IDT. More...
void	test_idt ()
	Tests whether interrupt handlers can be registered. More...
INTN EFIAPI	ShellAppMain (UINTN argc, CHAR16 **argv)
	Main function, gets invoked by UEFI shell. More...

Detailed Description

This application will show some information about the CPU.

Author

Richard Nusser

Copyright

2017-2018 Richard Nusser

License

GPLv3 (see http://www.gnu.org/licenses/)

See also

https://github.com/rinusser/UEFIStarter

Macro Definition Documentation

CI

#define CI	(		NAME,
			REGISTER,
			BIT
	)		Print(L ## #NAME ": %d\n",(REGISTER&1<<BIT)>0)

helper macro to quickly output a CPUID flag

Parameters

NAME	the flag's name
REGISTER	the variable to read from
BIT	the flag's bit offset

Function Documentation

rdmsr()

UINT64 rdmsr

(

UINT64

rcx

)

Reads a CPU's model-specific register.

Parameters

rcx	the register selector for the RDMSR instruction

Returns

the register's value

read_msrs()

void read_msrs

(

)

Prints a selection of model-specific CPU registers.

Currently the selection is very narrow: the function just prints the APIC base address.

handler()

void handler

(

)

Interrupt handler, this will be registered by test_idt() and should get called when signalling the interrupt there.

This will set rax (the return register) to the current instruction pointer.

write_idt_entry_address()

void write_idt_entry_address	(	void *	entry_base,
		void *	func
	)

Writes an interrupt handler address into the IDT.

Parameters

entry_base	the start of the IDT entry to write to
func	the handler's address

test_idt()

void test_idt

(

)

Tests whether interrupt handlers can be registered.

This will register handler() as the handling function for INT 3, then signal INT 3. The handler should get called and should return its instruction pointer (which should be very close to handler()'s address). This function checks the returned instruction pointer.

ShellAppMain()

INTN EFIAPI ShellAppMain	(	UINTN	argc,
		CHAR16 **	argv
	)

Main function, gets invoked by UEFI shell.

Parameters

argc	the number of command-line arguments passed
argv	the command-line arguments passed

Returns

an EFI status code for the shell