gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
# Copyright (C) 2021-2022 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# This file is part of the GDB testsuite. It validates the Python
# disassembler API.
load_lib gdb-python.exp
standard_testfile
if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile} "debug"] } {
return -1
}
# Skip all tests if Python scripting is not enabled.
if { [skip_python_tests] } { continue }
if ![runto_main] then {
fail "can't run to main"
return 0
}
set pyfile [gdb_remote_download host ${srcdir}/${subdir}/${testfile}.py]
gdb_test "source ${pyfile}" "Python script imported" \
"import python scripts"
gdb_breakpoint [gdb_get_line_number "Break here."]
gdb_continue_to_breakpoint "Break here."
set curr_pc [get_valueof "/x" "\$pc" "*unknown*"]
gdb_test_no_output "python current_pc = ${curr_pc}"
# The current pc will be something like 0x1234 with no leading zeros.
# However, in the disassembler output addresses are padded with zeros.
# This substitution changes 0x1234 to 0x0*1234, which can then be used
# as a regexp in the disassembler output matching.
set curr_pc_pattern [string replace ${curr_pc} 0 1 "0x0*"]
# Grab the name of the current architecture, this is used in the tests
# patterns below.
set curr_arch [get_python_valueof "gdb.selected_inferior().architecture().name()" "*unknown*"]
# Helper proc that removes all registered disassemblers.
proc py_remove_all_disassemblers {} {
gdb_test_no_output "python remove_all_python_disassemblers()"
}
# A list of test plans. Each plan is a list of two elements, the
# first element is the name of a class in py-disasm.py, this is a
# disassembler class. The second element is a pattern that should be
# matched in the disassembler output.
#
# Each different disassembler tests some different feature of the
# Python disassembler API.
set unknown_error_pattern "unknown disassembler error \\(error = -1\\)"
set addr_pattern "\r\n=> ${curr_pc_pattern} <\[^>\]+>:\\s+"
set base_pattern "${addr_pattern}nop"
set test_plans \
[list \
[list "" "${base_pattern}\r\n.*"] \
[list "GlobalNullDisassembler" "${base_pattern}\r\n.*"] \
[list "GlobalPreInfoDisassembler" "${base_pattern}\\s+## ad = $hex, ar = ${curr_arch}\r\n.*"] \
[list "GlobalPostInfoDisassembler" "${base_pattern}\\s+## ad = $hex, ar = ${curr_arch}\r\n.*"] \
[list "GlobalReadDisassembler" "${base_pattern}\\s+## bytes =( $hex)+\r\n.*"] \
[list "GlobalAddrDisassembler" "${base_pattern}\\s+## addr = ${curr_pc_pattern} <\[^>\]+>\r\n.*"] \
[list "GdbErrorEarlyDisassembler" "${addr_pattern}GdbError instead of a result\r\n${unknown_error_pattern}"] \
[list "RuntimeErrorEarlyDisassembler" "${addr_pattern}Python Exception <class 'RuntimeError'>: RuntimeError instead of a result\r\n\r\n${unknown_error_pattern}"] \
[list "GdbErrorLateDisassembler" "${addr_pattern}GdbError after builtin disassembler\r\n${unknown_error_pattern}"] \
[list "RuntimeErrorLateDisassembler" "${addr_pattern}Python Exception <class 'RuntimeError'>: RuntimeError after builtin disassembler\r\n\r\n${unknown_error_pattern}"] \
[list "MemoryErrorEarlyDisassembler" "${base_pattern}\\s+## AFTER ERROR\r\n.*"] \
[list "MemoryErrorLateDisassembler" "${addr_pattern}Cannot access memory at address ${curr_pc_pattern}"] \
[list "RethrowMemoryErrorDisassembler" "${addr_pattern}Cannot access memory at address $hex"] \
[list "ReadMemoryMemoryErrorDisassembler" "${addr_pattern}Cannot access memory at address ${curr_pc_pattern}"] \
[list "ReadMemoryGdbErrorDisassembler" "${addr_pattern}read_memory raised GdbError\r\n${unknown_error_pattern}"] \
[list "ReadMemoryRuntimeErrorDisassembler" "${addr_pattern}Python Exception <class 'RuntimeError'>: read_memory raised RuntimeError\r\n\r\n${unknown_error_pattern}"] \
[list "ReadMemoryCaughtMemoryErrorDisassembler" "${addr_pattern}nop\r\n.*"] \
[list "ReadMemoryCaughtGdbErrorDisassembler" "${addr_pattern}nop\r\n.*"] \
[list "ReadMemoryCaughtRuntimeErrorDisassembler" "${addr_pattern}nop\r\n.*"] \
[list "MemorySourceNotABufferDisassembler" "${addr_pattern}Python Exception <class 'TypeError'>: Result from read_memory is not a buffer\r\n\r\n${unknown_error_pattern}"] \
[list "MemorySourceBufferTooLongDisassembler" "${addr_pattern}Python Exception <class 'ValueError'>: Buffer returned from read_memory is sized $decimal instead of the expected $decimal\r\n\r\n${unknown_error_pattern}"] \
[list "ResultOfWrongType" "${addr_pattern}Python Exception <class 'TypeError'>: Result is not a DisassemblerResult.\r\n.*"] \
[list "ResultWithInvalidLength" "${addr_pattern}Python Exception <class 'ValueError'>: Invalid length attribute: length must be greater than 0.\r\n.*"] \
[list "ResultWithInvalidString" "${addr_pattern}Python Exception <class 'ValueError'>: String attribute must not be empty.\r\n.*"]]
# Now execute each test plan.
foreach plan $test_plans {
set global_disassembler_name [lindex $plan 0]
set expected_pattern [lindex $plan 1]
with_test_prefix "global_disassembler=${global_disassembler_name}" {
# Remove all existing disassemblers.
py_remove_all_disassemblers
# If we have a disassembler to load, do it now.
if { $global_disassembler_name != "" } {
gdb_test_no_output "python add_global_disassembler($global_disassembler_name)"
}
2022-07-20 20:57:08 +08:00
# Disassemble test, and check the disassembler output.
gdb_test "disassemble test" $expected_pattern
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
}
}
# Check some errors relating to DisassemblerResult creation.
with_test_prefix "DisassemblerResult errors" {
gdb_test "python gdb.disassembler.DisassemblerResult(0, 'abc')" \
[multi_line \
"ValueError: Length must be greater than 0." \
"Error while executing Python code."]
gdb_test "python gdb.disassembler.DisassemblerResult(-1, 'abc')" \
[multi_line \
"ValueError: Length must be greater than 0." \
"Error while executing Python code."]
gdb_test "python gdb.disassembler.DisassemblerResult(1, '')" \
[multi_line \
"ValueError: String must not be empty." \
"Error while executing Python code."]
}
# Check that the architecture specific disassemblers can override the
# global disassembler.
#
# First, register a global disassembler, and check it is in place.
with_test_prefix "GLOBAL tagging disassembler" {
py_remove_all_disassemblers
gdb_test_no_output "python gdb.disassembler.register_disassembler(TaggingDisassembler(\"GLOBAL\"), None)"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\\s+## tag = GLOBAL\r\n.*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
}
# Now register an architecture specific disassembler, and check it
# overrides the global disassembler.
with_test_prefix "LOCAL tagging disassembler" {
gdb_test_no_output "python gdb.disassembler.register_disassembler(TaggingDisassembler(\"LOCAL\"), \"${curr_arch}\")"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\\s+## tag = LOCAL\r\n.*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
}
# Now remove the architecture specific disassembler, and check that
# the global disassembler kicks back in.
with_test_prefix "GLOBAL tagging disassembler again" {
gdb_test_no_output "python gdb.disassembler.register_disassembler(None, \"${curr_arch}\")"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\\s+## tag = GLOBAL\r\n.*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
}
# Check that a DisassembleInfo becomes invalid after the call into the
# disassembler.
with_test_prefix "DisassembleInfo becomes invalid" {
py_remove_all_disassemblers
gdb_test_no_output "python add_global_disassembler(GlobalCachingDisassembler)"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\\s+## CACHED\r\n.*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
gdb_test "python GlobalCachingDisassembler.check()" "PASS"
}
# Test the memory source aspect of the builtin disassembler.
with_test_prefix "memory source api" {
py_remove_all_disassemblers
gdb_test_no_output "python analyzing_disassembler = add_global_disassembler(AnalyzingDisassembler)"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\r\n.*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
gdb_test "python analyzing_disassembler.find_replacement_candidate()" \
"Replace from $hex to $hex with NOP"
2022-07-20 20:57:08 +08:00
gdb_test "disassemble test" "${base_pattern}\r\n.*" \
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
"second disassembler pass"
gdb_test "python analyzing_disassembler.check()" \
"PASS"
}
# Test the 'maint info python-disassemblers command.
with_test_prefix "maint info python-disassemblers" {
py_remove_all_disassemblers
gdb_test "maint info python-disassemblers" "No Python disassemblers registered\\." \
"list disassemblers, none registered"
gdb_test_no_output "python disasm = add_global_disassembler(BuiltinDisassembler)"
gdb_test "maint info python-disassemblers" \
[multi_line \
"Architecture\\s+Disassember Name" \
"GLOBAL\\s+BuiltinDisassembler\\s+\\(Matches current architecture\\)"] \
"list disassemblers, single global disassembler"
gdb_test_no_output "python arch = gdb.selected_inferior().architecture().name()"
gdb_test_no_output "python gdb.disassembler.register_disassembler(disasm, arch)"
gdb_test "maint info python-disassemblers" \
[multi_line \
"Architecture\\s+Disassember Name" \
"\[^\r\n\]+BuiltinDisassembler\\s+\\(Matches current architecture\\)" \
"GLOBAL\\s+BuiltinDisassembler"] \
"list disassemblers, multiple disassemblers registered"
2022-07-20 20:57:08 +08:00
# Check that disassembling main (with the BuiltinDisassembler in
# place) doesn't cause GDB to crash. The hope is that
# disassembling main will result in a call to print_address, which
# is where the problem was.
gdb_test "disassemble main" ".*"
gdb/python: implement the print_insn extension language hook
This commit extends the Python API to include disassembler support.
The motivation for this commit was to provide an API by which the user
could write Python scripts that would augment the output of the
disassembler.
To achieve this I have followed the model of the existing libopcodes
disassembler, that is, instructions are disassembled one by one. This
does restrict the type of things that it is possible to do from a
Python script, i.e. all additional output has to fit on a single line,
but this was all I needed, and creating something more complex would,
I think, require greater changes to how GDB's internal disassembler
operates.
The disassembler API is contained in the new gdb.disassembler module,
which defines the following classes:
DisassembleInfo
Similar to libopcodes disassemble_info structure, has read-only
properties: address, architecture, and progspace. And has methods:
__init__, read_memory, and is_valid.
Each time GDB wants an instruction disassembled, an instance of
this class is passed to a user written disassembler function, by
reading the properties, and calling the methods (and other support
methods in the gdb.disassembler module) the user can perform and
return the disassembly.
Disassembler
This is a base-class which user written disassemblers should
inherit from. This base class provides base implementations of
__init__ and __call__ which the user written disassembler should
override.
DisassemblerResult
This class can be used to hold the result of a call to the
disassembler, it's really just a wrapper around a string (the text
of the disassembled instruction) and a length (in bytes). The user
can return an instance of this class from Disassembler.__call__ to
represent the newly disassembled instruction.
The gdb.disassembler module also provides the following functions:
register_disassembler
This function registers an instance of a Disassembler sub-class
as a disassembler, either for one specific architecture, or, as a
global disassembler for all architectures.
builtin_disassemble
This provides access to GDB's builtin disassembler. A common
use case that I see is augmenting the existing disassembler output.
The user code can call this function to have GDB disassemble the
instruction in the normal way. The user gets back a
DisassemblerResult object, which they can then read in order to
augment the disassembler output in any way they wish.
This function also provides a mechanism to intercept the
disassemblers reads of memory, thus the user can adjust what GDB
sees when it is disassembling.
The included documentation provides a more detailed description of the
API.
There is also a new CLI command added:
maint info python-disassemblers
This command is defined in the Python gdb.disassemblers module, and
can be used to list the currently registered Python disassemblers.
2021-09-18 01:12:34 +08:00
}
# Check the attempt to create a "new" DisassembleInfo object fails.
with_test_prefix "Bad DisassembleInfo creation" {
gdb_test_no_output "python my_info = InvalidDisassembleInfo()"
gdb_test "python print(my_info.is_valid())" "True"
gdb_test "python gdb.disassembler.builtin_disassemble(my_info)" \
[multi_line \
"RuntimeError: DisassembleInfo is no longer valid\\." \
"Error while executing Python code\\."]
}
