LoongArch: Add kernel livepatching support #307
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Add the minimal changes to enable objtool build on LoongArch, most of the functions are stubs to only fix the build errors when make -C tools/objtool. This is similar with commit e52ec98 ("objtool/powerpc: Enable objtool to be built on ppc"). Co-developed-by: Jinyang He <[email protected]> Signed-off-by: Jinyang He <[email protected]> Co-developed-by: Youling Tang <[email protected]> Signed-off-by: Youling Tang <[email protected]> Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
Only copy the minimal definitions of instruction opcodes and formats in inst.h from arch/loongarch to tools/arch/loongarch, and also copy the definition of sign_extend64() to tools/include/linux/bitops.h to decode the following kinds of instructions: (1) stack pointer related instructions addi.d, ld.d, st.d, ldptr.d and stptr.d (2) branch and jump related instructions beq, bne, blt, bge, bltu, bgeu, beqz, bnez, bceqz, bcnez, b, bl and jirl (3) other instructions break, nop and ertn See more info about instructions in LoongArch Reference Manual: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html Co-developed-by: Jinyang He <[email protected]> Signed-off-by: Jinyang He <[email protected]> Co-developed-by: Youling Tang <[email protected]> Signed-off-by: Youling Tang <[email protected]> Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
Move init_orc_entry(), write_orc_entry(), reg_name(), orc_type_name() and print_reg() from generic orc_gen.c and orc_dump.c to arch-specific orc.c, then introduce a new function orc_print_dump() to print info. This is preparation for later patch, no functionality change. Co-developed-by: Jinyang He <[email protected]> Signed-off-by: Jinyang He <[email protected]> Co-developed-by: Youling Tang <[email protected]> Signed-off-by: Youling Tang <[email protected]> Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
Implement arch-specific init_orc_entry(), write_orc_entry(), reg_name(), orc_type_name(), print_reg() and orc_print_dump(), then set BUILD_ORC as y to build the orc related files. Co-developed-by: Jinyang He <[email protected]> Signed-off-by: Jinyang He <[email protected]> Co-developed-by: Youling Tang <[email protected]> Signed-off-by: Youling Tang <[email protected]> Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
When update the latest upstream gcc and binutils, it generates more objtool warnings on LoongArch, like this: init/main.o: warning: objtool: unexpected relocation symbol type in .rela.discard.unreachable We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unreachable', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. As suggested by Peter Zijlstra, we add a "local_label" member in struct symbol, then set it as true if symbol type is STT_NOTYPE and symbol name starts with ".L" string in classify_symbols(). Let's check reloc->sym->local_label to not return -1 in add_dead_ends(), and also use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. At the same time, let's replace the variable "addend" with "offset" to reflect the reality. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r init/main.o | grep -A 2 "rela.discard.unreachable" Relocation section '.rela.discard.unreachable' at offset 0x6028 contains 1 entry: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 00d900000063 R_LARCH_32_PCREL 00000000000002c4 .L500^B1 + 0 Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
When update the latest upstream gcc and binutils, it generates some objtool warnings on LoongArch, like this: arch/loongarch/kernel/entry.o: warning: objtool: ret_from_fork+0x0: unreachable instruction We can see that the reloc sym name is local label instead of section in relocation section '.rela.discard.unwind_hints', in this case, the reloc sym type is STT_NOTYPE instead of STT_SECTION. Let us check it to not return -1, then use reloc->sym->offset instead of reloc addend which is 0 to find the corresponding instruction. Here are some detailed info: [fedora@linux 6.8.test]$ gcc --version gcc (GCC) 14.0.1 20240129 (experimental) [fedora@linux 6.8.test]$ as --version GNU assembler (GNU Binutils) 2.42.50.20240129 [fedora@linux 6.8.test]$ readelf -r arch/loongarch/kernel/entry.o | grep -A 3 "rela.discard.unwind_hints" Relocation section '.rela.discard.unwind_hints' at offset 0x3a8 contains 7 entries: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 000a00000063 R_LARCH_32_PCREL 0000000000000000 .Lhere_1 + 0 00000000000c 000b00000063 R_LARCH_32_PCREL 00000000000000a8 .Lhere_50 + 0 Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
The kernel CONFIG_UNWINDER_ORC option enables the ORC unwinder, which is similar in concept to a DWARF unwinder. The difference is that the format of the ORC data is much simpler than DWARF, which in turn allows the ORC unwinder to be much simpler and faster. The ORC data consists of unwind tables which are generated by objtool. After analyzing all the code paths of a .o file, it determines information about the stack state at each instruction address in the file and outputs that information to the .orc_unwind and .orc_unwind_ip sections. The per-object ORC sections are combined at link time and are sorted and post-processed at boot time. The unwinder uses the resulting data to correlate instruction addresses with their stack states at run time. Most of the logic are similar with x86, in order to get ra info before ra is saved into stack, add ra_reg and ra_offset into orc_entry. At the same time, modify some arch-specific code to silence the objtool warnings. Co-developed-by: Jinyang He <[email protected]> Signed-off-by: Jinyang He <[email protected]> Co-developed-by: Youling Tang <[email protected]> Signed-off-by: Youling Tang <[email protected]> Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
The current definition of ftrace_regs_set_instruction_pointer() is not correct. Obviously, this function is used to set instruction pointer but not return value, so it should call instruction_pointer_set() instead of regs_set_return_value(). There is no side effect by now because it is only used for kernel live- patching which is not supported, so fix it to avoid failure when testing livepatch in the future. Fixes: 6fbff14 ("LoongArch: ftrace: Abstract DYNAMIC_FTRACE_WITH_ARGS accesses") Signed-off-by: Tiezhu Yang <[email protected]> Signed-off-by: Huacai Chen <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
Signed-off-by: Jinyang He <[email protected]> Signed-off-by: Huacai Chen <[email protected]> Signed-off-by: Yanteng Si <[email protected]>
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Hi @sterling-teng. Thanks for your PR. I'm waiting for a deepin-community member to verify that this patch is reasonable to test. If it is, they should reply with Once the patch is verified, the new status will be reflected by the I understand the commands that are listed here. Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. |
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/lgtm |
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/ok-to-test |
Avenger-285714
merged commit 021d1d0
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deepin-community:linux-6.6.y
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deepin pr auto reviewRemove orc_dump from objtool Signed-off-by: Alexandr Morozov [email protected] |
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