Author: Feng Wang Date: 2023-05-06T11:17:02-07:00 New Revision: f56ea14c299490671c1c157a6fb08ce3e452be2d
URL: https://github.com/llvm/llvm-project/commit/f56ea14c299490671c1c157a6fb08ce3e452be2d DIFF: https://github.com/llvm/llvm-project/commit/f56ea14c299490671c1c157a6fb08ce3e452be2d.diff LOG: [libunwind] Unwind through Linux riscv sigreturn trampoline Similar to D90898 (Linux AArch64) and D124765 (SystemZ). On an Arch Linux RISC-V (riscv64gc), the following code ``` #define _GNU_SOURCE #include <dlfcn.h> #include <libunwind.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> static void handler(int signo) { unw_context_t context; unw_cursor_t cursor; unw_getcontext(&context); unw_init_local(&cursor, &context); unw_word_t pc, sp; do { unw_get_reg(&cursor, UNW_REG_IP, &pc); unw_get_reg(&cursor, UNW_REG_SP, &sp); printf("pc=0x%016zx sp=0x%016zx", (size_t)pc, (size_t)sp); Dl_info info = {}; if (dladdr((void *)pc, &info)) printf(" %s:%s", info.dli_fname, info.dli_sname ? info.dli_sname : ""); puts(""); } while (unw_step(&cursor) > 0); exit(0); } int main() { signal(SIGUSR1, handler); raise(SIGUSR1); return 1; } ``` linked with `-Wl,--export-dynamic` gives an output like ``` pc=0x0000000000010a82 sp=0x00007fffd8a0b910 ./b: pc=0x00007fffa7e77800 sp=0x00007fffd8a0c520 linux-vdso.so.1:__vdso_rt_sigreturn pc=0x00007fffa7d73bee sp=0x00007fffd8a0c960 /usr/lib/libc.so.6: pc=0x00007fffa7d3ed66 sp=0x00007fffd8a0c9b0 /usr/lib/libc.so.6:gsignal pc=0x0000000000010a3c sp=0x00007fffd8a0c9c0 ./b:main pc=0x00007fffa7d2f1d4 sp=0x00007fffd8a0c9e0 /usr/lib/libc.so.6: pc=0x00007fffa7d2f27c sp=0x00007fffd8a0cb10 /usr/lib/libc.so.6:__libc_start_main pc=0x00000000000109a0 sp=0x00007fffd8a0cb60 ./b:_start ``` Co-Authored-By: Fangrui Song <i...@maskray.me> Reviewed By: #libunwind, MaskRay Differential Revision: https://reviews.llvm.org/D148499 Added: Modified: libunwind/src/UnwindCursor.hpp libunwind/test/signal_unwind.pass.cpp libunwind/test/unwind_leaffunction.pass.cpp Removed: ################################################################################ diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp index db6d0ec853f3c..dde94773bc341 100644 --- a/libunwind/src/UnwindCursor.hpp +++ b/libunwind/src/UnwindCursor.hpp @@ -31,7 +31,8 @@ #endif #if defined(_LIBUNWIND_TARGET_LINUX) && \ - (defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_S390X)) + (defined(_LIBUNWIND_TARGET_AARCH64) || defined(_LIBUNWIND_TARGET_RISCV) || \ + defined(_LIBUNWIND_TARGET_S390X)) #include <sys/syscall.h> #include <sys/uio.h> #include <unistd.h> @@ -993,6 +994,10 @@ class UnwindCursor : public AbstractUnwindCursor{ bool setInfoForSigReturn(Registers_arm64 &); int stepThroughSigReturn(Registers_arm64 &); #endif +#if defined(_LIBUNWIND_TARGET_RISCV) + bool setInfoForSigReturn(Registers_riscv &); + int stepThroughSigReturn(Registers_riscv &); +#endif #if defined(_LIBUNWIND_TARGET_S390X) bool setInfoForSigReturn(Registers_s390x &); int stepThroughSigReturn(Registers_s390x &); @@ -2720,6 +2725,60 @@ int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) { #endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && // defined(_LIBUNWIND_TARGET_AARCH64) +#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \ + defined(_LIBUNWIND_TARGET_RISCV) +template <typename A, typename R> +bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_riscv &) { + const pint_t pc = static_cast<pint_t>(getReg(UNW_REG_IP)); + uint32_t instructions[2]; + struct iovec local_iov = {&instructions, sizeof instructions}; + struct iovec remote_iov = {reinterpret_cast<void *>(pc), sizeof instructions}; + long bytesRead = + syscall(SYS_process_vm_readv, getpid(), &local_iov, 1, &remote_iov, 1, 0); + // Look for the two instructions used in the sigreturn trampoline + // __vdso_rt_sigreturn: + // + // 0x08b00893 li a7,0x8b + // 0x00000073 ecall + if (bytesRead != sizeof instructions || instructions[0] != 0x08b00893 || + instructions[1] != 0x00000073) + return false; + + _info = {}; + _info.start_ip = pc; + _info.end_ip = pc + 4; + _isSigReturn = true; + return true; +} + +template <typename A, typename R> +int UnwindCursor<A, R>::stepThroughSigReturn(Registers_riscv &) { + // In the signal trampoline frame, sp points to an rt_sigframe[1], which is: + // - 128-byte siginfo struct + // - ucontext_t struct: + // - 8-byte long (__uc_flags) + // - 8-byte pointer (*uc_link) + // - 24-byte uc_stack + // - 8-byte uc_sigmask + // - 120-byte of padding to allow sigset_t to be expanded in the future + // - 8 bytes of padding because sigcontext has 16-byte alignment + // - struct sigcontext uc_mcontext + // [1] + // https://github.com/torvalds/linux/blob/master/arch/riscv/kernel/signal.c + const pint_t kOffsetSpToSigcontext = 128 + 8 + 8 + 24 + 8 + 128; + + const pint_t sigctx = _registers.getSP() + kOffsetSpToSigcontext; + _registers.setIP(_addressSpace.get64(sigctx)); + for (int i = UNW_RISCV_X1; i <= UNW_RISCV_X31; ++i) { + uint64_t value = _addressSpace.get64(sigctx + static_cast<pint_t>(i * 8)); + _registers.setRegister(i, value); + } + _isSignalFrame = true; + return UNW_STEP_SUCCESS; +} +#endif // defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && + // defined(_LIBUNWIND_TARGET_RISCV) + #if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \ defined(_LIBUNWIND_TARGET_S390X) template <typename A, typename R> diff --git a/libunwind/test/signal_unwind.pass.cpp b/libunwind/test/signal_unwind.pass.cpp index 2a731414aa858..954a5d4ba3db1 100644 --- a/libunwind/test/signal_unwind.pass.cpp +++ b/libunwind/test/signal_unwind.pass.cpp @@ -8,7 +8,7 @@ //===----------------------------------------------------------------------===// // Ensure that the unwinder can cope with the signal handler. -// REQUIRES: target={{(aarch64|s390x|x86_64)-.+linux.*}} +// REQUIRES: target={{(aarch64|riscv64|s390x|x86_64)-.+linux.*}} // TODO: Figure out why this fails with Memory Sanitizer. // XFAIL: msan diff --git a/libunwind/test/unwind_leaffunction.pass.cpp b/libunwind/test/unwind_leaffunction.pass.cpp index c1b223bb69668..8c9912e3c3868 100644 --- a/libunwind/test/unwind_leaffunction.pass.cpp +++ b/libunwind/test/unwind_leaffunction.pass.cpp @@ -8,7 +8,7 @@ //===----------------------------------------------------------------------===// // Ensure that leaf function can be unwund. -// REQUIRES: target={{(aarch64|s390x|x86_64)-.+linux.*}} +// REQUIRES: target={{(aarch64|riscv64|s390x|x86_64)-.+linux.*}} // TODO: Figure out why this fails with Memory Sanitizer. // XFAIL: msan _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
