kernel/linux.git/tools/objtool/orc_dump.c, branch v6.6.131

x86,objtool: Split UNWIND_HINT_EMPTY in two

2023-03-23T22:18:58+00:00

Mark reported that the ORC unwinder incorrectly marks an unwind as reliable when the unwind terminates prematurely in the dark corners of return_to_handler() due to lack of information about the next frame. The problem is UNWIND_HINT_EMPTY is used in two different situations: 1) The end of the kernel stack unwind before hitting user entry, boot code, or fork entry 2) A blind spot in ORC coverage where the unwinder has to bail due to lack of information about the next frame The ORC unwinder has no way to tell the difference between the two. When it encounters an undefined stack state with 'end=1', it blindly marks the stack reliable, which can break the livepatch consistency model. Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and UNWIND_HINT_END_OF_STACK. Reported-by: Mark Rutland Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Acked-by: Steven Rostedt (Google) Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org

x86,objtool: Introduce ORC_TYPE_*

2023-03-23T22:18:57+00:00

Unwind hints and ORC entry types are two distinct things. Separate them out more explicitly. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/cc879d38fff8a43f8f7beb2fd56e35a5a384d7cd.1677683419.git.jpoimboe@kernel.org

objtool: Add objtool_types.h

2023-03-23T22:18:56+00:00

Reduce the amount of header sync churn by splitting the shared objtool.h types into a new file. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/dec622720851210ceafa12d4f4c5f9e73c832152.1677683419.git.jpoimboe@kernel.org

x86/unwind/orc: Add 'signal' field to ORC metadata

2023-02-11T11:37:51+00:00

Add a 'signal' field which allows unwind hints to specify whether the instruction pointer should be taken literally (like for most interrupts and exceptions) rather than decremented (like for call stack return addresses) when used to find the next ORC entry. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/d2c5ec4d83a45b513d8fd72fab59f1a8cfa46871.1676068346.git.jpoimboe@kernel.org

objtool: Use target file endianness instead of a compiled constant

2022-11-18T08:00:15+00:00

Some architectures like powerpc support both endianness, it's therefore not possible to fix the endianness via arch/endianness.h because there is no easy way to get the target endianness at build time. Use the endianness recorded in the file objtool is working on. Tested-by: Naveen N. Rao Reviewed-by: Naveen N. Rao Acked-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221114175754.1131267-10-sv@linux.ibm.com

x86/unwind/orc: Change REG_SP_INDIRECT

2021-02-10T19:53:51+00:00

Currently REG_SP_INDIRECT is unused but means (%rsp + offset), change it to mean (%rsp) + offset. The reason is that we're going to swizzle stack in the middle of a C function with non-trivial stack footprint. This means that when the unwinder finds the ToS, it needs to dereference it (%rsp) and then add the offset to the next frame, resulting in: (%rsp) + offset This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP) and thus needs to retain the current (%rbp + offset). Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf

objtool: Rework header include paths

2021-01-14T00:13:14+00:00

Currently objtool headers are being included either by their base name or included via ../ from a parent directory. In case of a base name usage: #include "warn.h" #include "arch_elf.h" it does not make it apparent from which directory the file comes from. To make it slightly better, and actually to avoid name clashes some arch specific files have "arch_" suffix. And files from an arch folder have to revert to including via ../ e.g: #include "../../elf.h" With additional architectures support and the code base growth there is a need for clearer headers naming scheme for multiple reasons: 1. to make it instantly obvious where these files come from (objtool itself / objtool arch|generic folders / some other external files), 2. to avoid name clashes of objtool arch specific headers, potential obtool arch generic headers and the system header files (there is /usr/include/elf.h already), 3. to avoid ../ includes and improve code readability. 4. to give a warm fuzzy feeling to developers who are mostly kernel developers and are accustomed to linux kernel headers arranging scheme. Doesn't this make it instantly obvious where are these files come from? #include #include And doesn't it look nicer to avoid ugly ../ includes? Which also guarantees this is elf.h from the objtool and not /usr/include/elf.h. #include This patch defines and implements new objtool headers arranging scheme. Which is: - all generic headers go to include/objtool (similar to include/linux) - all arch headers go to arch/$(SRCARCH)/include/arch (to get arch prefix). This is similar to linux arch specific "asm/*" headers but we are not abusing "asm" name and calling it what it is. This also helps to prevent name clashes (arch is not used in system headers or kernel exports). To bring objtool to this state the following things are done: 1. current top level tools/objtool/ headers are moved into include/objtool/ subdirectory, 2. arch specific headers, currently only arch/x86/include/ are moved into arch/x86/include/arch/ and were stripped of "arch_" suffix, 3. new -I$(srctree)/tools/objtool/include include path to make includes like possible, 4. rewriting file includes, 5. make git not to ignore include/objtool/ subdirectory. Signed-off-by: Vasily Gorbik Acked-by: Peter Zijlstra (Intel) Acked-by: Masami Hiramatsu Signed-off-by: Josh Poimboeuf

objtool: Fix x86 orc generation on big endian cross-compiles

2021-01-14T00:13:13+00:00

Correct objtool orc generation endianness problems to enable fully functional x86 cross-compiles on big endian hardware. Introduce bswap_if_needed() macro, which does a byte swap if target endianness doesn't match the host, i.e. cross-compilation for little endian on big endian and vice versa. The macro is used for conversion of multi-byte values which are read from / about to be written to a target native endianness ELF file. Signed-off-by: Vasily Gorbik Acked-by: Peter Zijlstra (Intel) Acked-by: Masami Hiramatsu Signed-off-by: Josh Poimboeuf

objtool: Make unwind hint definitions available to other architectures

2020-09-10T15:43:13+00:00

Unwind hints are useful to provide objtool with information about stack states in non-standard functions/code. While the type of information being provided might be very arch specific, the mechanism to provide the information can be useful for other architectures. Move the relevant unwint hint definitions for all architectures to see. [ jpoimboe: REGS_IRET -> REGS_PARTIAL ] Signed-off-by: Julien Thierry Signed-off-by: Josh Poimboeuf

objtool: Enable compilation of objtool for all architectures

2020-05-20T14:17:28+00:00

Objtool currently only compiles for x86 architectures. This is fine as it presently does not support tooling for other architectures. However, we would like to be able to convert other kernel tools to run as objtool sub commands because they too process ELF object files. This will allow us to convert tools such as recordmcount to use objtool's ELF code. Since much of recordmcount's ELF code is copy-paste code to/from a variety of other kernel tools (look at modpost for example) this means that if we can convert recordmcount we can convert more. We define weak definitions for subcommand entry functions and other weak definitions for shared functions critical to building existing subcommands. These return 127 when the command is missing which signify tools that do not exist on all architectures. In this case the "check" and "orc" tools do not exist on all architectures so we only add them for x86. Future changes adding support for "check", to arm64 for example, can then modify the SUBCMD_CHECK variable when building for arm64. Objtool is not currently wired in to KConfig to be built for other architectures because it's not needed for those architectures and there are no commands it supports other than those for x86. As more command support is enabled on various architectures the necessary KConfig changes can be made (e.g. adding "STACK_VALIDATION") to trigger building objtool. [ jpoimboe: remove aliases, add __weak macro, add error messages ] Cc: Julien Thierry Signed-off-by: Matt Helsley Signed-off-by: Josh Poimboeuf