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-rw-r--r--tools/dump-auxv.py141
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diff --git a/tools/dump-auxv.py b/tools/dump-auxv.py
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+++ b/tools/dump-auxv.py
@@ -0,0 +1,141 @@
+#!/usr/bin/python
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# Note: the no-value-for-parameter here is expected, as the click module
+# decorators modify function arguments which pylint doesn't know
+# pylint: disable=no-value-for-parameter
+
+"""
+A program to parse auxv (e.g. /proc/self/auxv).
+
+By default, current arch is assumed, but options can be used to override the
+endianness and word size.
+"""
+
+import struct
+
+import click
+
+# From /usr/include/elf.h
+AT_AUXV = {
+ 'AT_NULL' : 0, # End of vector
+ 'AT_IGNORE' : 1, # Entry should be ignored
+ 'AT_EXECFD' : 2, # File descriptor of program
+ 'AT_PHDR' : 3, # Program headers for program
+ 'AT_PHENT' : 4, # Size of program header entry
+ 'AT_PHNUM' : 5, # Number of program headers
+ 'AT_PAGESZ' : 6, # System page size
+ 'AT_BASE' : 7, # Base address of interpreter
+ 'AT_FLAGS' : 8, # Flags
+ 'AT_ENTRY' : 9, # Entry point of program
+ 'AT_NOTELF' : 10, # Program is not ELF
+ 'AT_UID' : 11, # Real uid
+ 'AT_EUID' : 12, # Effective uid
+ 'AT_GID' : 13, # Real gid
+ 'AT_EGID' : 14, # Effective gid
+ 'AT_CLKTCK' : 17, # Frequency of times()
+
+ # Some more special a_type values describing the hardware.
+ 'AT_PLATFORM' : 15, # String identifying platform.
+ 'AT_HWCAP' : 16, # Machine-dependent hints about processor capabilities.
+
+ # This entry gives some information about the FPU initialization performed by the kernel.
+ 'AT_FPUCW' : 18, # Used FPU control word.
+
+ # Cache block sizes.
+ 'AT_DCACHEBSIZE' : 19, # Data cache block size.
+ 'AT_ICACHEBSIZE' : 20, # Instruction cache block size.
+ 'AT_UCACHEBSIZE' : 21, # Unified cache block size.
+
+ # A special ignored value for PPC, used by the kernel to control the
+ # interpretation of the AUXV. Must be > 16.
+ 'AT_IGNOREPPC' : 22, # Entry should be ignored.
+
+ 'AT_SECURE' : 23, # Boolean, was exec setuid-like?
+
+ 'AT_BASE_PLATFORM' : 24, # String identifying real platforms.
+
+ 'AT_RANDOM' : 25, # Address of 16 random bytes.
+
+ 'AT_HWCAP2' : 26, # More machine-dependent hints about processor capabilities.
+
+ 'AT_EXECFN' : 31, # Filename of executable.
+
+ # Pointer to the global system page used for system calls and other nice things.
+ 'AT_SYSINFO' : 32,
+ 'AT_SYSINFO_EHDR' : 33,
+
+ # Shapes of the caches. Bits 0-3 contains associativity; bits 4-7 contains
+ # log2 of line size; mask those to get cache size.
+ 'AT_L1I_CACHESHAPE' : 34,
+ 'AT_L1D_CACHESHAPE' : 35,
+ 'AT_L2_CACHESHAPE' : 36,
+ 'AT_L3_CACHESHAPE' : 37,
+
+ # Shapes of the caches, with more room to describe them.
+ # GEOMETRY are comprised of cache line size in bytes in the bottom 16 bits
+ # and the cache associativity in the next 16 bits.
+ 'AT_L1I_CACHESIZE' : 40,
+ 'AT_L1I_CACHEGEOMETRY' : 41,
+ 'AT_L1D_CACHESIZE' : 42,
+ 'AT_L1D_CACHEGEOMETRY' : 43,
+ 'AT_L2_CACHESIZE' : 44,
+ 'AT_L2_CACHEGEOMETRY' : 45,
+ 'AT_L3_CACHESIZE' : 46,
+ 'AT_L3_CACHEGEOMETRY' : 47,
+
+ 'AT_MINSIGSTKSZ' : 51, # Stack needed for signal delivery
+}
+AT_AUXV_NAMES = {v:k for k,v in AT_AUXV.items()}
+
+@click.command(help=__doc__)
+@click.option('-b', '--big-endian', 'endian',
+ flag_value='>',
+ help='Input is big-endian')
+@click.option('-l', '--little-endian', 'endian',
+ flag_value='<',
+ help='Input is little-endian')
+@click.option('-3', '--32', 'field_width',
+ flag_value=32,
+ help='Input is 32-bit')
+@click.option('-6', '--64', 'field_width',
+ flag_value=64,
+ help='Input is 64-bit')
+@click.argument('file',
+ type=click.File(mode='rb'))
+def dump(endian, field_width, file):
+ data = file.read()
+
+ if field_width is None:
+ field_width = struct.calcsize('P') * 8
+ if endian is None:
+ endian = '@'
+
+ width = {32:'II', 64:'QQ'}[field_width]
+
+ format_str = f'{endian}{width}'
+ print(f'# {format_str=}')
+
+ seen_null = False
+
+ for item in struct.iter_unpack(format_str, data):
+ key, val = item
+ name = AT_AUXV_NAMES.get(key, f'unknown ({key})')
+ if name.endswith(('UID', 'GID')):
+ pref, fmt = '', 'd'
+ else:
+ pref, fmt = '0x', 'x'
+
+ if seen_null:
+ print('# trailing garbage after AT_NULL')
+
+ print(f'{name:18} = {pref}{val:{fmt}}')
+
+ if name == 'AT_NULL':
+ seen_null = True
+
+ if not seen_null:
+ print('# array not terminated with AT_NULL')
+
+if __name__ == '__main__':
+ dump()