1 files changed, 9 insertions, 69 deletions

diff --git a/absl/debugging/internal/stacktrace_riscv-inl.inc b/absl/debugging/internal/stacktrace_riscv-inl.inc
index a0f23739..a9e2c323 100644
--- a/absl/debugging/internal/stacktrace_riscv-inl.inc
+++ b/absl/debugging/internal/stacktrace_riscv-inl.inc
@@ -32,54 +32,10 @@
 #include <iostream>
 
 #include "absl/base/attributes.h"
-#include "absl/debugging/internal/address_is_readable.h"
-#include "absl/debugging/internal/vdso_support.h"
 #include "absl/debugging/stacktrace.h"
 
 static const uintptr_t kUnknownFrameSize = 0;
 
-#if defined(__linux__)
-// Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
-static const unsigned char *GetKernelRtSigreturnAddress() {
-  constexpr uintptr_t kImpossibleAddress = 0;
-  ABSL_CONST_INIT static std::atomic<uintptr_t> memoized(kImpossibleAddress);
-  uintptr_t address = memoized.load(std::memory_order_relaxed);
-  if (address != kImpossibleAddress) {
-    return reinterpret_cast<const unsigned char *>(address);
-  }
-
-  address = reinterpret_cast<uintptr_t>(nullptr);
-
-#if ABSL_HAVE_VDSO_SUPPORT
-  absl::debugging_internal::VDSOSupport vdso;
-  if (vdso.IsPresent()) {
-    absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info;
-    // Symbol versioning pulled from arch/riscv/kernel/vdso/vdso.lds at v5.10.
-    auto lookup = [&](int type) {
-      return vdso.LookupSymbol("__vdso_rt_sigreturn", "LINUX_4.15", type,
-                               &symbol_info);
-    };
-    if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) ||
-        symbol_info.address == nullptr) {
-      // Unexpected: VDSO is present, yet the expected symbol is missing or
-      // null.
-      assert(false && "VDSO is present, but doesn't have expected symbol");
-    } else {
-      if (reinterpret_cast<uintptr_t>(symbol_info.address) !=
-          kImpossibleAddress) {
-        address = reinterpret_cast<uintptr_t>(symbol_info.address);
-      } else {
-        assert(false && "VDSO returned invalid address");
-      }
-    }
-  }
-#endif
-
-  memoized.store(address, std::memory_order_relaxed);
-  return reinterpret_cast<const unsigned char *>(address);
-}
-#endif  // __linux__
-
 // Compute the size of a stack frame in [low..high).  We assume that low < high.
 // Return size of kUnknownFrameSize.
 template <typename T>
@@ -115,40 +71,23 @@ static void ** NextStackFrame(void **old_frame_pointer, const void *uc,
   // $sp ->|      ...       |
   //       +----------------+
   void **new_frame_pointer = reinterpret_cast<void **>(old_frame_pointer[-2]);
+  uintptr_t frame_pointer = reinterpret_cast<uintptr_t>(new_frame_pointer);
 
   // The RISCV ELF psABI mandates that the stack pointer is always 16-byte
   // aligned.
   // TODO(#1236) this doesn't hold for ILP32E which only mandates a 4-byte
   // alignment.
-  if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 15) != 0)
+  if (frame_pointer & 15)
     return nullptr;
 
-#if defined(__linux__)
-  if (WITH_CONTEXT && uc != nullptr) {
-    // Check to see if next frame's return address is __kernel_rt_sigreturn.
-    if (old_frame_pointer[-1] == GetKernelRtSigreturnAddress()) {
-      const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
-      // old_frame_pointer is not suitable for unwinding, look at ucontext to
-      // discover frame pointer before signal.
-      //
+  // If the new frame pointer matches the signal context, avoid terminating
+  // early to deal with alternate signal stacks.
+  if (WITH_CONTEXT)
+    if (const ucontext_t *ucv = static_cast<const ucontext_t *>(uc))
       // RISCV ELF psABI has the frame pointer at x8/fp/s0.
       // -- RISCV psABI Table 18.2
-      void **const pre_signal_frame_pointer =
-          reinterpret_cast<void **>(ucv->uc_mcontext.__gregs[8]);
-
-      // Check the alleged frame pointer is actually readable. This is to
-      // prevent "double fault" in case we hit the first fault due to stack
-      // corruption.
-      if (!absl::debugging_internal::AddressIsReadable(
-              pre_signal_frame_pointer))
-        return nullptr;
-
-      // Alleged frame pointer is readable, use it for further unwinding.
-      new_frame_pointer = pre_signal_frame_pointer;
-    }
-    return new_frame_pointer;
-  }
-#endif
+      if (ucv->uc_mcontext.__gregs[8] == frame_pointer)
+        return new_frame_pointer;
 
   // Check frame size.  In strict mode, we assume frames to be under 100,000
   // bytes.  In non-strict mode, we relax the limit to 1MB.
@@ -165,6 +104,7 @@ static void ** NextStackFrame(void **old_frame_pointer, const void *uc,
         reinterpret_cast<uintptr_t>(new_frame_pointer) > range.second)
       return nullptr;
   }
+
   if (frame_size > max_size)
     return nullptr;