ec7044437e
Disables allowing the python argparse library from automatically shortening command line arguments, this prevents issues whereby a new command is added and code that wrongly uses the shortened command of an existing argument which is the same as the new command being added will silently change script behaviour. Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>
315 lines
9.4 KiB
Python
Executable file
315 lines
9.4 KiB
Python
Executable file
#!/usr/bin/env python3
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#
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# Copyright (c) 2017 Intel Corporation
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#
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# SPDX-License-Identifier: Apache-2.0
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"""Generate Interrupt Descriptor Table for x86 CPUs.
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This script generates the interrupt descriptor table (IDT) for x86.
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Please consult the IA Architecture SW Developer Manual, volume 3,
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for more details on this data structure.
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This script accepts as input the zephyr_prebuilt.elf binary,
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which is a link of the Zephyr kernel without various build-time
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generated data structures (such as the IDT) inserted into it.
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This kernel image has been properly padded such that inserting
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these data structures will not disturb the memory addresses of
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other symbols. From the kernel binary we read a special section
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"intList" which contains the desired interrupt routing configuration
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for the kernel, populated by instances of the IRQ_CONNECT() macro.
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This script outputs three binary tables:
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1. The interrupt descriptor table itself.
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2. A bitfield indicating which vectors in the IDT are free for
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installation of dynamic interrupts at runtime.
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3. An array which maps configured IRQ lines to their associated
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vector entries in the IDT, used to program the APIC at runtime.
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"""
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import argparse
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import sys
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import struct
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import os
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import elftools
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from packaging import version
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from elftools.elf.elffile import ELFFile
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from elftools.elf.sections import SymbolTableSection
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if version.parse(elftools.__version__) < version.parse('0.24'):
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sys.exit("pyelftools is out of date, need version 0.24 or later")
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# This will never change, first selector in the GDT after the null selector
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KERNEL_CODE_SEG = 0x08
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# These exception vectors push an error code onto the stack.
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ERR_CODE_VECTORS = [8, 10, 11, 12, 13, 14, 17]
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def debug(text):
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if not args.verbose:
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return
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sys.stdout.write(os.path.basename(sys.argv[0]) + ": " + text + "\n")
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def error(text):
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sys.exit(os.path.basename(sys.argv[0]) + ": " + text)
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# See Section 6.11 of the Intel Architecture Software Developer's Manual
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gate_desc_format = "<HHBBH"
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def create_irq_gate(handler, dpl):
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present = 1
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gate_type = 0xE # 32-bit interrupt gate
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type_attr = gate_type | (dpl << 5) | (present << 7)
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offset_hi = handler >> 16
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offset_lo = handler & 0xFFFF
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data = struct.pack(gate_desc_format, offset_lo, KERNEL_CODE_SEG, 0,
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type_attr, offset_hi)
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return data
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def create_task_gate(tss, dpl):
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present = 1
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gate_type = 0x5 # 32-bit task gate
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type_attr = gate_type | (dpl << 5) | (present << 7)
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data = struct.pack(gate_desc_format, 0, tss, 0, type_attr, 0)
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return data
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def create_idt_binary(idt_config, filename):
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with open(filename, "wb") as fp:
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for handler, tss, dpl in idt_config:
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if handler and tss:
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error("entry specifies both handler function and tss")
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if not handler and not tss:
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error("entry does not specify either handler or tss")
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if handler:
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data = create_irq_gate(handler, dpl)
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else:
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data = create_task_gate(tss, dpl)
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fp.write(data)
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map_fmt = "<B"
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def create_irq_vec_map_binary(irq_vec_map, filename):
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with open(filename, "wb") as fp:
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for i in irq_vec_map:
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fp.write(struct.pack(map_fmt, i))
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def priority_range(prio):
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# Priority levels are represented as groups of 16 vectors within the IDT
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base = 32 + (prio * 16)
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return range(base, base + 16)
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def update_irq_vec_map(irq_vec_map, irq, vector, max_irq):
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# No IRQ associated; exception or software interrupt
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if irq == -1:
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return
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if irq >= max_irq:
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error("irq %d specified, but CONFIG_MAX_IRQ_LINES is %d" %
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(irq, max_irq))
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# This table will never have values less than 32 since those are for
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# exceptions; 0 means unconfigured
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if irq_vec_map[irq] != 0:
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error("multiple vector assignments for interrupt line %d" % irq)
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debug("assign IRQ %d to vector %d" % (irq, vector))
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irq_vec_map[irq] = vector
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def setup_idt(spur_code, spur_nocode, intlist, max_vec, max_irq):
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irq_vec_map = [0 for i in range(max_irq)]
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vectors = [None for i in range(max_vec)]
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# Pass 1: sanity check and set up hard-coded interrupt vectors
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for handler, irq, prio, vec, dpl, tss in intlist:
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if vec == -1:
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if prio == -1:
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error("entry does not specify vector or priority level")
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continue
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if vec >= max_vec:
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error("Vector %d specified, but size of IDT is only %d vectors" %
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(vec, max_vec))
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if vectors[vec] is not None:
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error("Multiple assignments for vector %d" % vec)
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vectors[vec] = (handler, tss, dpl)
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update_irq_vec_map(irq_vec_map, irq, vec, max_irq)
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# Pass 2: set up priority-based interrupt vectors
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for handler, irq, prio, vec, dpl, tss in intlist:
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if vec != -1:
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continue
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for vi in priority_range(prio):
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if vi >= max_vec:
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break
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if vectors[vi] is None:
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vec = vi
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break
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if vec == -1:
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error("can't find a free vector in priority level %d" % prio)
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vectors[vec] = (handler, tss, dpl)
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update_irq_vec_map(irq_vec_map, irq, vec, max_irq)
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# Pass 3: fill in unused vectors with spurious handler at dpl=0
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for i in range(max_vec):
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if vectors[i] is not None:
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continue
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if i in ERR_CODE_VECTORS:
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handler = spur_code
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else:
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handler = spur_nocode
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vectors[i] = (handler, 0, 0)
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return vectors, irq_vec_map
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def get_symbols(obj):
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for section in obj.iter_sections():
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if isinstance(section, SymbolTableSection):
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return {sym.name: sym.entry.st_value
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for sym in section.iter_symbols()}
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raise LookupError("Could not find symbol table")
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# struct genidt_header_s {
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# uint32_t spurious_addr;
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# uint32_t spurious_no_error_addr;
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# int32_t num_entries;
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# };
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intlist_header_fmt = "<II"
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# struct genidt_entry_s {
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# uint32_t isr;
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# int32_t irq;
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# int32_t priority;
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# int32_t vector_id;
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# int32_t dpl;
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# int32_t tss;
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# };
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intlist_entry_fmt = "<Iiiiii"
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def get_intlist(elf):
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intdata = elf.get_section_by_name("intList").data()
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header_sz = struct.calcsize(intlist_header_fmt)
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header = struct.unpack_from(intlist_header_fmt, intdata, 0)
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intdata = intdata[header_sz:]
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spurious_code = header[0]
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spurious_nocode = header[1]
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debug("spurious handler (code) : %s" % hex(header[0]))
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debug("spurious handler (no code) : %s" % hex(header[1]))
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intlist = [i for i in
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struct.iter_unpack(intlist_entry_fmt, intdata)]
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debug("Configured interrupt routing")
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debug("handler irq pri vec dpl")
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debug("--------------------------")
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for irq in intlist:
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debug("{0:<10} {1:<3} {2:<3} {3:<3} {4:<2}".format(
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hex(irq[0]),
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"-" if irq[1] == -1 else irq[1],
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"-" if irq[2] == -1 else irq[2],
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"-" if irq[3] == -1 else irq[3],
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irq[4]))
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return (spurious_code, spurious_nocode, intlist)
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def parse_args():
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global args
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parser = argparse.ArgumentParser(
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description=__doc__,
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formatter_class=argparse.RawDescriptionHelpFormatter, allow_abbrev=False)
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parser.add_argument("-m", "--vector-map", required=True,
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help="Output file mapping IRQ lines to IDT vectors")
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parser.add_argument("-o", "--output-idt", required=True,
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help="Output file containing IDT binary")
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parser.add_argument("-a", "--output-vectors-alloc", required=False,
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help="Output file indicating allocated vectors")
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parser.add_argument("-k", "--kernel", required=True,
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help="Zephyr kernel image")
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parser.add_argument("-v", "--verbose", action="store_true",
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help="Print extra debugging information")
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args = parser.parse_args()
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if "VERBOSE" in os.environ:
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args.verbose = 1
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def create_irq_vectors_allocated(vectors, spur_code, spur_nocode, filename):
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# Construct a bitfield over all the IDT vectors, where if bit n is 1,
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# that vector is free. those vectors have either of the two spurious
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# interrupt handlers installed, they are free for runtime installation
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# of interrupts
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num_chars = (len(vectors) + 7) // 8
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vbits = num_chars*[0]
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for i, (handler, _, _) in enumerate(vectors):
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if handler not in (spur_code, spur_nocode):
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continue
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vbit_index = i // 8
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vbit_val = 1 << (i % 8)
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vbits[vbit_index] = vbits[vbit_index] | vbit_val
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with open(filename, "wb") as fp:
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for char in vbits:
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fp.write(struct.pack("<B", char))
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def main():
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parse_args()
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with open(args.kernel, "rb") as fp:
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kernel = ELFFile(fp)
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syms = get_symbols(kernel)
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spur_code, spur_nocode, intlist = get_intlist(kernel)
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max_irq = syms["CONFIG_MAX_IRQ_LINES"]
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max_vec = syms["CONFIG_IDT_NUM_VECTORS"]
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vectors, irq_vec_map = setup_idt(spur_code, spur_nocode, intlist, max_vec,
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max_irq)
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create_idt_binary(vectors, args.output_idt)
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create_irq_vec_map_binary(irq_vec_map, args.vector_map)
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if args.output_vectors_alloc:
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create_irq_vectors_allocated(vectors, spur_code, spur_nocode,
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args.output_vectors_alloc)
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if __name__ == "__main__":
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main()
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