141 lines
3.9 KiB
Python
Executable File
141 lines
3.9 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Copyright (c) 2017 Linaro Limited
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#
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# SPDX-License-Identifier: Apache-2.0
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"""
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Script to generate gperf tables mapping threads to their privileged mode stacks
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Some MPU devices require that memory region definitions be aligned to their
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own size, which must be a power of two. This introduces difficulties in
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reserving memory for the thread's supervisor mode stack inline with the
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K_THREAD_STACK_DEFINE() macro.
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Instead, the stack used when a user thread elevates privileges is allocated
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elsewhere in memory, and a gperf table is created to be able to quickly
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determine where the supervisor mode stack is in memory. This is accomplished
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by scanning the DWARF debug information in zephyr_prebuilt.elf, identifying
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instances of 'struct k_thread', and emitting a gperf configuration file which
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allocates memory for each thread's privileged stack and creates the table
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mapping thread addresses to these stacks.
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"""
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import sys
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import argparse
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import struct
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from elf_helper import ElfHelper
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kobjects = {
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"_k_thread_stack_element": (None, False)
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}
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header = """%compare-lengths
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%define lookup-function-name z_priv_stack_map_lookup
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%language=ANSI-C
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%global-table
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%struct-type
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"""
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# Each privilege stack buffer needs to respect the alignment
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# constraints as specified in arm/arch.h.
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priv_stack_decl_temp = ("static u8_t __used"
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" __aligned(Z_PRIVILEGE_STACK_ALIGN)"
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" priv_stack_%x[CONFIG_PRIVILEGED_STACK_SIZE];\n")
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includes = """#include <kernel.h>
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#include <string.h>
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"""
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structure = """struct _k_priv_stack_map {
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char *name;
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u8_t *priv_stack_addr;
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};
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%%
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"""
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# Different versions of gperf have different prototypes for the lookup
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# function, best to implement the wrapper here. The pointer value itself is
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# turned into a string, we told gperf to expect binary strings that are not
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# NULL-terminated.
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footer = """%%
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u8_t *z_priv_stack_find(void *obj)
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{
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const struct _k_priv_stack_map *map =
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z_priv_stack_map_lookup((const char *)obj, sizeof(void *));
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return map->priv_stack_addr;
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}
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"""
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def write_gperf_table(fp, eh, objs):
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fp.write(header)
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# priv stack declarations
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fp.write("%{\n")
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fp.write(includes)
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for obj_addr in objs:
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fp.write(priv_stack_decl_temp % (obj_addr))
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fp.write("%}\n")
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# structure declaration
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fp.write(structure)
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for obj_addr in objs:
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byte_str = struct.pack("<I" if eh.little_endian else ">I", obj_addr)
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fp.write("\"")
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for byte in byte_str:
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val = "\\x%02x" % byte
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fp.write(val)
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fp.write("\",priv_stack_%x\n" % obj_addr)
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fp.write(footer)
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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)
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parser.add_argument("-k", "--kernel", required=True,
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help="Input zephyr ELF binary")
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parser.add_argument(
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"-o", "--output", required=True,
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help="Output list of kernel object addresses for gperf use")
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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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def main():
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parse_args()
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eh = ElfHelper(args.kernel, args.verbose, kobjects, [])
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syms = eh.get_symbols()
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max_threads = syms["CONFIG_MAX_THREAD_BYTES"] * 8
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objs = eh.find_kobjects(syms)
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if not objs:
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sys.stderr.write("WARNING: zero kobject found in %s\n"
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% args.kernel)
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thread_counter = eh.get_thread_counter()
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if thread_counter > max_threads:
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sys.exit("Too many thread objects ({})\n"
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"Increase CONFIG_MAX_THREAD_BYTES to {}"
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.format(thread_counter, -(-thread_counter // 8)))
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with open(args.output, "w") as fp:
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write_gperf_table(fp, eh, objs)
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if __name__ == "__main__":
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main()
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