arch/x86/gen_idt.py - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 #!/usr/bin/env python3
 #
 # Copyright (c) 2017 Intel Corporation
 #
 # SPDX-License-Identifier: Apache-2.0

 """Generate Interrupt Descriptor Table for x86 CPUs.

 This script generates the interrupt descriptor table (IDT) for x86.
 Please consult the IA Architecture SW Developer Manual, volume 3,
 for more details on this data structure.

 This script accepts as input the zephyr_prebuilt.elf binary,
 which is a link of the Zephyr kernel without various build-time
 generated data structures (such as the IDT) inserted into it.
 This kernel image has been properly padded such that inserting
 these data structures will not disturb the memory addresses of
 other symbols. From the kernel binary we read a special section
 "intList" which contains the desired interrupt routing configuration
 for the kernel, populated by instances of the IRQ_CONNECT() macro.

 This script outputs three binary tables:

 1. The interrupt descriptor table itself.
 2. A bitfield indicating which vectors in the IDT are free for
    installation of dynamic interrupts at runtime.
 3. An array which maps configured IRQ lines to their associated
    vector entries in the IDT, used to program the APIC at runtime.
 """

 import argparse
 import sys
 import struct
 import os
 import elftools
 from packaging import version
 from elftools.elf.elffile import ELFFile
 from elftools.elf.sections import SymbolTableSection

 if version.parse(elftools.__version__) < version.parse('0.24'):
     sys.exit("pyelftools is out of date, need version 0.24 or later")

 # This will never change, first selector in the GDT after the null selector
 KERNEL_CODE_SEG = 0x08

 # These exception vectors push an error code onto the stack.
 ERR_CODE_VECTORS = [8, 10, 11, 12, 13, 14, 17]


 def debug(text):
     if not args.verbose:
         return
     sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n")


 def error(text):
     sys.exit(os.path.basename(sys.argv[0]) + ": " + text)


 # See Section 6.11 of the Intel Architecture Software Developer's Manual
 gate_desc_format = "<HHBBH"


 def create_irq_gate(handler, dpl):
     present = 1
     gate_type = 0xE  # 32-bit interrupt gate
     type_attr = gate_type | (dpl << 5) | (present << 7)

     offset_hi = handler >> 16
     offset_lo = handler & 0xFFFF

     data = struct.pack(gate_desc_format, offset_lo, KERNEL_CODE_SEG, 0,
                        type_attr, offset_hi)
     return data


 def create_task_gate(tss, dpl):
     present = 1
     gate_type = 0x5  # 32-bit task gate
     type_attr = gate_type | (dpl << 5) | (present << 7)

     data = struct.pack(gate_desc_format, 0, tss, 0, type_attr, 0)
     return data


 def create_idt_binary(idt_config, filename):
     with open(filename, "wb") as fp:
         for handler, tss, dpl in idt_config:
             if handler and tss:
                 error("entry specifies both handler function and tss")

             if not handler and not tss:
                 error("entry does not specify either handler or tss")

             if handler:
                 data = create_irq_gate(handler, dpl)
             else:
                 data = create_task_gate(tss, dpl)

             fp.write(data)


 map_fmt = "<B"


 def create_irq_vec_map_binary(irq_vec_map, filename):
     with open(filename, "wb") as fp:
         for i in irq_vec_map:
             fp.write(struct.pack(map_fmt, i))


 def priority_range(prio):
     # Priority levels are represented as groups of 16 vectors within the IDT
     base = 32 + (prio * 16)
     return range(base, base + 16)


 def update_irq_vec_map(irq_vec_map, irq, vector, max_irq):
     # No IRQ associated; exception or software interrupt
     if irq == -1:
         return

     if irq >= max_irq:
         error("irq %d specified, but CONFIG_MAX_IRQ_LINES is %d" %
               (irq, max_irq))

     # This table will never have values less than 32 since those are for
     # exceptions; 0 means unconfigured
     if irq_vec_map[irq] != 0:
         error("multiple vector assignments for interrupt line %d" % irq)

     debug("assign IRQ %d to vector %d" % (irq, vector))
     irq_vec_map[irq] = vector


 def setup_idt(spur_code, spur_nocode, intlist, max_vec, max_irq):
     irq_vec_map = [0 for i in range(max_irq)]
     vectors = [None for i in range(max_vec)]

     # Pass 1: sanity check and set up hard-coded interrupt vectors
     for handler, irq, prio, vec, dpl, tss in intlist:
         if vec == -1:
             if prio == -1:
                 error("entry does not specify vector or priority level")
             continue

         if vec >= max_vec:
             error("Vector %d specified, but size of IDT is only %d vectors" %
                   (vec, max_vec))

         if vectors[vec] is not None:
             error("Multiple assignments for vector %d" % vec)

         vectors[vec] = (handler, tss, dpl)
         update_irq_vec_map(irq_vec_map, irq, vec, max_irq)

     # Pass 2: set up priority-based interrupt vectors
     for handler, irq, prio, vec, dpl, tss in intlist:
         if vec != -1:
             continue

         for vi in priority_range(prio):
             if vi >= max_vec:
                 break
             if vectors[vi] is None:
                 vec = vi
                 break

         if vec == -1:
             error("can't find a free vector in priority level %d" % prio)

         vectors[vec] = (handler, tss, dpl)
         update_irq_vec_map(irq_vec_map, irq, vec, max_irq)

     # Pass 3: fill in unused vectors with spurious handler at dpl=0
     for i in range(max_vec):
         if vectors[i] is not None:
             continue

         if i in ERR_CODE_VECTORS:
             handler = spur_code
         else:
             handler = spur_nocode

         vectors[i] = (handler, 0, 0)

     return vectors, irq_vec_map


 def get_symbols(obj):
     for section in obj.iter_sections():
         if isinstance(section, SymbolTableSection):
             return {sym.name: sym.entry.st_value
                     for sym in section.iter_symbols()}

     raise LookupError("Could not find symbol table")

 # struct genidt_header_s {
 #	uint32_t spurious_addr;
 #	uint32_t spurious_no_error_addr;
 #	int32_t num_entries;
 # };


 intlist_header_fmt = "<II"

 # struct genidt_entry_s {
 #	uint32_t isr;
 #	int32_t irq;
 #	int32_t priority;
 #	int32_t vector_id;
 #	int32_t dpl;
 #	int32_t tss;
 # };

 intlist_entry_fmt = "<Iiiiii"


 def get_intlist(elf):
     intdata = elf.get_section_by_name("intList").data()

     header_sz = struct.calcsize(intlist_header_fmt)
     header = struct.unpack_from(intlist_header_fmt, intdata, 0)
     intdata = intdata[header_sz:]

     spurious_code = header[0]
     spurious_nocode = header[1]

     debug("spurious handler (code)    : %s" % hex(header[0]))
     debug("spurious handler (no code) : %s" % hex(header[1]))

     intlist = [i for i in
                struct.iter_unpack(intlist_entry_fmt, intdata)]

     debug("Configured interrupt routing")
     debug("handler    irq pri vec dpl")
     debug("--------------------------")

     for irq in intlist:
         debug("{0:<10} {1:<3} {2:<3} {3:<3} {4:<2}".format(
             hex(irq[0]),
             "-" if irq[1] == -1 else irq[1],
             "-" if irq[2] == -1 else irq[2],
             "-" if irq[3] == -1 else irq[3],
             irq[4]))

     return (spurious_code, spurious_nocode, intlist)


 def parse_args():
     global args
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter, allow_abbrev=False)

     parser.add_argument("-m", "--vector-map", required=True,
                         help="Output file mapping IRQ lines to IDT vectors")
     parser.add_argument("-o", "--output-idt", required=True,
                         help="Output file containing IDT binary")
     parser.add_argument("-a", "--output-vectors-alloc", required=False,
                         help="Output file indicating allocated vectors")
     parser.add_argument("-k", "--kernel", required=True,
                         help="Zephyr kernel image")
     parser.add_argument("-v", "--verbose", action="store_true",
                         help="Print extra debugging information")
     args = parser.parse_args()
     if "VERBOSE" in os.environ:
         args.verbose = 1


 def create_irq_vectors_allocated(vectors, spur_code, spur_nocode, filename):
     # Construct a bitfield over all the IDT vectors, where if bit n is 1,
     # that vector is free. those vectors have either of the two spurious
     # interrupt handlers installed, they are free for runtime installation
     # of interrupts
     num_chars = (len(vectors) + 7) // 8
     vbits = num_chars*[0]
     for i, (handler, _, _) in enumerate(vectors):
         if handler not in (spur_code, spur_nocode):
             continue

         vbit_index = i // 8
         vbit_val = 1 << (i % 8)
         vbits[vbit_index] = vbits[vbit_index] | vbit_val

     with open(filename, "wb") as fp:
         for char in vbits:
             fp.write(struct.pack("<B", char))


 def main():
     parse_args()

     with open(args.kernel, "rb") as fp:
         kernel = ELFFile(fp)

         syms = get_symbols(kernel)
         spur_code, spur_nocode, intlist = get_intlist(kernel)

     max_irq = syms["CONFIG_MAX_IRQ_LINES"]
     max_vec = syms["CONFIG_IDT_NUM_VECTORS"]

     vectors, irq_vec_map = setup_idt(spur_code, spur_nocode, intlist, max_vec,
                                      max_irq)

     create_idt_binary(vectors, args.output_idt)
     create_irq_vec_map_binary(irq_vec_map, args.vector_map)
     if args.output_vectors_alloc:
         create_irq_vectors_allocated(vectors, spur_code, spur_nocode,
                                      args.output_vectors_alloc)


 if __name__ == "__main__":
     main()
	#!/usr/bin/env python3
	#
	# Copyright (c) 2017 Intel Corporation
	#
	# SPDX-License-Identifier: Apache-2.0

	"""Generate Interrupt Descriptor Table for x86 CPUs.

	This script generates the interrupt descriptor table (IDT) for x86.
	Please consult the IA Architecture SW Developer Manual, volume 3,
	for more details on this data structure.

	This script accepts as input the zephyr_prebuilt.elf binary,
	which is a link of the Zephyr kernel without various build-time
	generated data structures (such as the IDT) inserted into it.
	This kernel image has been properly padded such that inserting
	these data structures will not disturb the memory addresses of
	other symbols. From the kernel binary we read a special section
	"intList" which contains the desired interrupt routing configuration
	for the kernel, populated by instances of the IRQ_CONNECT() macro.

	This script outputs three binary tables:

	1. The interrupt descriptor table itself.
	2. A bitfield indicating which vectors in the IDT are free for
	installation of dynamic interrupts at runtime.
	3. An array which maps configured IRQ lines to their associated
	vector entries in the IDT, used to program the APIC at runtime.
	"""

	import argparse
	import sys
	import struct
	import os
	import elftools
	from packaging import version
	from elftools.elf.elffile import ELFFile
	from elftools.elf.sections import SymbolTableSection

	if version.parse(elftools.__version__) < version.parse('0.24'):
	sys.exit("pyelftools is out of date, need version 0.24 or later")

	# This will never change, first selector in the GDT after the null selector
	KERNEL_CODE_SEG = 0x08

	# These exception vectors push an error code onto the stack.
	ERR_CODE_VECTORS = [8, 10, 11, 12, 13, 14, 17]


	def debug(text):
	if not args.verbose:
	return
	sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n")


	def error(text):
	sys.exit(os.path.basename(sys.argv[0]) + ": " + text)


	# See Section 6.11 of the Intel Architecture Software Developer's Manual
	gate_desc_format = "<HHBBH"


	def create_irq_gate(handler, dpl):
	present = 1
	gate_type = 0xE # 32-bit interrupt gate
	type_attr = gate_type \| (dpl << 5) \| (present << 7)

	offset_hi = handler >> 16
	offset_lo = handler & 0xFFFF

	data = struct.pack(gate_desc_format, offset_lo, KERNEL_CODE_SEG, 0,
	type_attr, offset_hi)
	return data


	def create_task_gate(tss, dpl):
	present = 1
	gate_type = 0x5 # 32-bit task gate
	type_attr = gate_type \| (dpl << 5) \| (present << 7)

	data = struct.pack(gate_desc_format, 0, tss, 0, type_attr, 0)
	return data


	def create_idt_binary(idt_config, filename):
	with open(filename, "wb") as fp:
	for handler, tss, dpl in idt_config:
	if handler and tss:
	error("entry specifies both handler function and tss")

	if not handler and not tss:
	error("entry does not specify either handler or tss")

	if handler:
	data = create_irq_gate(handler, dpl)
	else:
	data = create_task_gate(tss, dpl)

	fp.write(data)


	map_fmt = "<B"


	def create_irq_vec_map_binary(irq_vec_map, filename):
	with open(filename, "wb") as fp:
	for i in irq_vec_map:
	fp.write(struct.pack(map_fmt, i))


	def priority_range(prio):
	# Priority levels are represented as groups of 16 vectors within the IDT
	base = 32 + (prio * 16)
	return range(base, base + 16)


	def update_irq_vec_map(irq_vec_map, irq, vector, max_irq):
	# No IRQ associated; exception or software interrupt
	if irq == -1:
	return

	if irq >= max_irq:
	error("irq %d specified, but CONFIG_MAX_IRQ_LINES is %d" %
	(irq, max_irq))

	# This table will never have values less than 32 since those are for
	# exceptions; 0 means unconfigured
	if irq_vec_map[irq] != 0:
	error("multiple vector assignments for interrupt line %d" % irq)

	debug("assign IRQ %d to vector %d" % (irq, vector))
	irq_vec_map[irq] = vector


	def setup_idt(spur_code, spur_nocode, intlist, max_vec, max_irq):
	irq_vec_map = [0 for i in range(max_irq)]
	vectors = [None for i in range(max_vec)]

	# Pass 1: sanity check and set up hard-coded interrupt vectors
	for handler, irq, prio, vec, dpl, tss in intlist:
	if vec == -1:
	if prio == -1:
	error("entry does not specify vector or priority level")
	continue

	if vec >= max_vec:
	error("Vector %d specified, but size of IDT is only %d vectors" %
	(vec, max_vec))

	if vectors[vec] is not None:
	error("Multiple assignments for vector %d" % vec)

	vectors[vec] = (handler, tss, dpl)
	update_irq_vec_map(irq_vec_map, irq, vec, max_irq)

	# Pass 2: set up priority-based interrupt vectors
	for handler, irq, prio, vec, dpl, tss in intlist:
	if vec != -1:
	continue

	for vi in priority_range(prio):
	if vi >= max_vec:
	break
	if vectors[vi] is None:
	vec = vi
	break

	if vec == -1:
	error("can't find a free vector in priority level %d" % prio)

	vectors[vec] = (handler, tss, dpl)
	update_irq_vec_map(irq_vec_map, irq, vec, max_irq)

	# Pass 3: fill in unused vectors with spurious handler at dpl=0
	for i in range(max_vec):
	if vectors[i] is not None:
	continue

	if i in ERR_CODE_VECTORS:
	handler = spur_code
	else:
	handler = spur_nocode

	vectors[i] = (handler, 0, 0)

	return vectors, irq_vec_map


	def get_symbols(obj):
	for section in obj.iter_sections():
	if isinstance(section, SymbolTableSection):
	return {sym.name: sym.entry.st_value
	for sym in section.iter_symbols()}

	raise LookupError("Could not find symbol table")

	# struct genidt_header_s {
	# uint32_t spurious_addr;
	# uint32_t spurious_no_error_addr;
	# int32_t num_entries;
	# };


	intlist_header_fmt = "<II"

	# struct genidt_entry_s {
	# uint32_t isr;
	# int32_t irq;
	# int32_t priority;
	# int32_t vector_id;
	# int32_t dpl;
	# int32_t tss;
	# };

	intlist_entry_fmt = "<Iiiiii"


	def get_intlist(elf):
	intdata = elf.get_section_by_name("intList").data()

	header_sz = struct.calcsize(intlist_header_fmt)
	header = struct.unpack_from(intlist_header_fmt, intdata, 0)
	intdata = intdata[header_sz:]

	spurious_code = header[0]
	spurious_nocode = header[1]

	debug("spurious handler (code) : %s" % hex(header[0]))
	debug("spurious handler (no code) : %s" % hex(header[1]))

	intlist = [i for i in
	struct.iter_unpack(intlist_entry_fmt, intdata)]

	debug("Configured interrupt routing")
	debug("handler irq pri vec dpl")
	debug("--------------------------")

	for irq in intlist:
	debug("{0:<10} {1:<3} {2:<3} {3:<3} {4:<2}".format(
	hex(irq[0]),
	"-" if irq[1] == -1 else irq[1],
	"-" if irq[2] == -1 else irq[2],
	"-" if irq[3] == -1 else irq[3],
	irq[4]))

	return (spurious_code, spurious_nocode, intlist)


	def parse_args():
	global args
	parser = argparse.ArgumentParser(
	description=__doc__,
	formatter_class=argparse.RawDescriptionHelpFormatter, allow_abbrev=False)

	parser.add_argument("-m", "--vector-map", required=True,
	help="Output file mapping IRQ lines to IDT vectors")
	parser.add_argument("-o", "--output-idt", required=True,
	help="Output file containing IDT binary")
	parser.add_argument("-a", "--output-vectors-alloc", required=False,
	help="Output file indicating allocated vectors")
	parser.add_argument("-k", "--kernel", required=True,
	help="Zephyr kernel image")
	parser.add_argument("-v", "--verbose", action="store_true",
	help="Print extra debugging information")
	args = parser.parse_args()
	if "VERBOSE" in os.environ:
	args.verbose = 1


	def create_irq_vectors_allocated(vectors, spur_code, spur_nocode, filename):
	# Construct a bitfield over all the IDT vectors, where if bit n is 1,
	# that vector is free. those vectors have either of the two spurious
	# interrupt handlers installed, they are free for runtime installation
	# of interrupts
	num_chars = (len(vectors) + 7) // 8
	vbits = num_chars*[0]
	for i, (handler, _, _) in enumerate(vectors):
	if handler not in (spur_code, spur_nocode):
	continue

	vbit_index = i // 8
	vbit_val = 1 << (i % 8)
	vbits[vbit_index] = vbits[vbit_index] \| vbit_val

	with open(filename, "wb") as fp:
	for char in vbits:
	fp.write(struct.pack("<B", char))


	def main():
	parse_args()

	with open(args.kernel, "rb") as fp:
	kernel = ELFFile(fp)

	syms = get_symbols(kernel)
	spur_code, spur_nocode, intlist = get_intlist(kernel)

	max_irq = syms["CONFIG_MAX_IRQ_LINES"]
	max_vec = syms["CONFIG_IDT_NUM_VECTORS"]

	vectors, irq_vec_map = setup_idt(spur_code, spur_nocode, intlist, max_vec,
	max_irq)

	create_idt_binary(vectors, args.output_idt)
	create_irq_vec_map_binary(irq_vec_map, args.vector_map)
	if args.output_vectors_alloc:
	create_irq_vectors_allocated(vectors, spur_code, spur_nocode,
	args.output_vectors_alloc)


	if __name__ == "__main__":
	main()