diff options
author | Feng Wang <wangfeng@eswincomputing.com> | 2023-05-06 11:17:02 -0700 |
---|---|---|
committer | Fangrui Song <i@maskray.me> | 2023-05-06 11:17:02 -0700 |
commit | f56ea14c299490671c1c157a6fb08ce3e452be2d (patch) | |
tree | e5bf5b63d9b4f78eee9e14a23b3324165b65f156 /libunwind | |
parent | 6b4bb103db37ec11507bf3f3fa26731bd16501a5 (diff) | |
download | llvm-f56ea14c299490671c1c157a6fb08ce3e452be2d.zip llvm-f56ea14c299490671c1c157a6fb08ce3e452be2d.tar.gz llvm-f56ea14c299490671c1c157a6fb08ce3e452be2d.tar.bz2 |
[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
Diffstat (limited to 'libunwind')
-rw-r--r-- | libunwind/src/UnwindCursor.hpp | 61 | ||||
-rw-r--r-- | libunwind/test/signal_unwind.pass.cpp | 2 | ||||
-rw-r--r-- | libunwind/test/unwind_leaffunction.pass.cpp | 2 |
3 files changed, 62 insertions, 3 deletions
diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp index db6d0ec..dde9477 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 @@ private: 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 &); @@ -2721,6 +2726,60 @@ int UnwindCursor<A, R>::stepThroughSigReturn(Registers_arm64 &) { // 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> bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_s390x &) { diff --git a/libunwind/test/signal_unwind.pass.cpp b/libunwind/test/signal_unwind.pass.cpp index 2a73141..954a5d4 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 c1b223bb..8c9912e 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 |