RISC-V: add support for restartable sequences

Add support for RSEQ, restartable sequences, for RISC-V.  This also adds
support for the related selftests.

Note: the selftests require a linker with 3e7bd7f2414 ("RISC-V: Fix
linker problems with tls copy relocs."), which was first released in
2.33 (from 2019).

* palmer/riscv-rseq:
  rseq/selftests: Add support for RISC-V
  RISC-V: Add support for restartable sequence

2 files changed, 6 insertions, 0 deletions

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index ed29e9c8f660..56ada2a583fa 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -225,6 +225,10 @@ ret_from_syscall:
 	 * (If it was configured with SECCOMP_RET_ERRNO/TRACE)
 	 */
 ret_from_syscall_rejected:
+#ifdef CONFIG_DEBUG_RSEQ
+	move a0, sp
+	call rseq_syscall
+#endif
 	/* Trace syscalls, but only if requested by the user. */
 	REG_L t0, TASK_TI_FLAGS(tp)
 	andi t0, t0, _TIF_SYSCALL_WORK
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index c2d5ecbe5526..16da3c3b53a1 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -258,6 +258,8 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 		}
 	}
 
+	rseq_signal_deliver(ksig, regs);
+
 	/* Set up the stack frame */
 	ret = setup_rt_frame(ksig, oldset, regs);