diff --git a/api/samples/opcodes.c b/api/samples/opcodes.c
index 86827d20719..1249ef7ca64 100644
--- a/api/samples/opcodes.c
+++ b/api/samples/opcodes.c
@@ -203,6 +203,8 @@ get_count_isa_idx(void *drcontext)
     case DR_ISA_ARM_THUMB: return ISA_ARM_THUMB;
 #elif defined(AARCH64)
     case DR_ISA_ARM_A64: return ISA_ARM_A64;
+#elif defined(RISCV64)
+    case DR_ISA_RV64IMAFDC: return ISA_RV64IMAFDC;
 #endif
     default: DR_ASSERT(false); /* NYI */
     }
diff --git a/core/unix/os_public.h b/core/unix/os_public.h
index 193dfcb6471..84899bcec88 100644
--- a/core/unix/os_public.h
+++ b/core/unix/os_public.h
@@ -205,7 +205,17 @@ typedef kernel_sigcontext_t sigcontext_t;
 #    define SC_SYSNUM_REG SC_R7
 #    define SC_RETURN_REG SC_R0
 #elif defined(RISCV64)
+#    define SC_XIP SC_FIELD(sc_regs.pc)
+#    define SC_RA SC_FIELD(sc_regs.ra)
+#    define SC_XSP SC_FIELD(sc_regs.sp)
+#    define SC_GP SC_FIELD(sc_regs.gp)
 #    define SC_TP SC_FIELD(sc_regs.tp)
+#    define SC_T0 SC_FIELD(sc_regs.t0)
+#    define SC_T1 SC_FIELD(sc_regs.t1)
+#    define SC_T2 SC_FIELD(sc_regs.t2)
+#    define SC_S0 SC_FIELD(sc_regs.s0)
+#    define SC_FP SC_FIELD(sc_regs.s0)
+#    define SC_S1 SC_FIELD(sc_regs.s1)
 #    define SC_A0 SC_FIELD(sc_regs.a0)
 #    define SC_A1 SC_FIELD(sc_regs.a1)
 #    define SC_A2 SC_FIELD(sc_regs.a2)
@@ -214,11 +224,20 @@ typedef kernel_sigcontext_t sigcontext_t;
 #    define SC_A5 SC_FIELD(sc_regs.a5)
 #    define SC_A6 SC_FIELD(sc_regs.a6)
 #    define SC_A7 SC_FIELD(sc_regs.a7)
-#    define SC_FP SC_FIELD(sc_regs.s0)
+#    define SC_S2 SC_FIELD(sc_regs.s2)
+#    define SC_S3 SC_FIELD(sc_regs.s3)
+#    define SC_S4 SC_FIELD(sc_regs.s4)
+#    define SC_S5 SC_FIELD(sc_regs.s5)
+#    define SC_S6 SC_FIELD(sc_regs.s6)
+#    define SC_S7 SC_FIELD(sc_regs.s7)
+#    define SC_S8 SC_FIELD(sc_regs.s8)
+#    define SC_S9 SC_FIELD(sc_regs.s9)
+#    define SC_S10 SC_FIELD(sc_regs.s10)
 #    define SC_S11 SC_FIELD(sc_regs.s11)
-#    define SC_RA SC_FIELD(sc_regs.ra)
-#    define SC_XIP SC_FIELD(sc_regs.pc)
-#    define SC_XSP SC_FIELD(sc_regs.sp)
+#    define SC_T3 SC_FIELD(sc_regs.t3)
+#    define SC_T4 SC_FIELD(sc_regs.t4)
+#    define SC_T5 SC_FIELD(sc_regs.t5)
+#    define SC_T6 SC_FIELD(sc_regs.t6)
 #    define SC_SYSNUM_REG SC_A7
 #    define SC_RETURN_REG SC_A0
 #endif /* X86/ARM */
diff --git a/ext/drcallstack/drcallstack.c b/ext/drcallstack/drcallstack.c
index 6812b7d1a88..03c8cb67b48 100644
--- a/ext/drcallstack/drcallstack.c
+++ b/ext/drcallstack/drcallstack.c
@@ -125,6 +125,13 @@ drcallstack_init_walk(dr_mcontext_t *mc, DR_PARAM_OUT drcallstack_walk_t **walk_
 #    elif defined(ARM)
     /* libunwind defines its own struct of 16 regs. */
     memcpy(&walk->uc.regs[0], &mc->r0, 16 * sizeof(walk->uc.regs[0]));
+#    elif defined(RISCV64)
+    /* unw_context_t is an alias of ucontext_t. */
+    sigcontext_t *sc = SIGCXT_FROM_UCXT(&walk->uc);
+    sc->SC_XIP = (ptr_uint_t)mc->pc;
+    /* x1..x31 is in the same order with no padding. */
+    memcpy(&sc->SC_RA, &mc->ra, 31 * sizeof(sc->SC_RA));
+    sc->SC_XSP = mc->xsp;
 #    else
     return DRCALLSTACK_ERROR_FEATURE_NOT_AVAILABLE;
 #    endif
diff --git a/suite/tests/CMakeLists.txt b/suite/tests/CMakeLists.txt
index 5b5d316baed..77723d43877 100644
--- a/suite/tests/CMakeLists.txt
+++ b/suite/tests/CMakeLists.txt
@@ -3585,7 +3585,7 @@ if (BUILD_SAMPLES)
             samples/${sample}_repstr "-log_to_stderr" "" "")
         endif ()
       elseif (sample STREQUAL "callstack")
-        set(sample.${sample}_expectbase "sample.callstack.control_flags")
+        set(sample.${sample}_expectbase "sample.callstack")
       endif()
     endforeach ()
   endif (NOT ANDROID)
@@ -6204,6 +6204,7 @@ if (RISCV64)
     code_api|sample.inscount.cleancall
     code_api|sample.inscount.prof-pcs.cleancall
     code_api|sample.opcode_count
+    code_api|sample.opcodes
     code_api|sample.signal
     code_api|sample.stl_test
     code_api|sample.syscall
diff --git a/suite/tests/common/sample.callstack.control_flags.templatex b/suite/tests/common/sample.callstack.templatex
similarity index 79%
rename from suite/tests/common/sample.callstack.control_flags.templatex
rename to suite/tests/common/sample.callstack.templatex
index 5c5d58f8633..2cedf77eae2 100644
--- a/suite/tests/common/sample.callstack.control_flags.templatex
+++ b/suite/tests/common/sample.callstack.templatex
@@ -1,7 +1,9 @@
 wrapping .*malloc
 malloc called from:
 .*
-#ifdef AARCHXX
+#if defined(RISCV64)
+Hello world!
+#elif defined(AARCHXX)
 OK 1 N
 OK 0 N
 OK 1 Z