csky: Add support for restartable sequence (9866d141) · Commits · 戴 / test

Copied and adapted from vincent's patch, but modified for csky. ref: https://lore.kernel.org/linux-riscv/1572919114-3886-3-git-send-email-vincent.chen@sifive.com/raw Add calls to rseq_signal_deliver(), rseq_handle_notify_resume() and rseq_syscall() to introduce RSEQ support. 1. Call the rseq_handle_notify_resume() function on return to userspace if TIF_NOTIFY_RESUME thread flag is set. 2. Call the rseq_signal_deliver() function to fixup on the pre-signal frame when a signal is delivered on top of a restartable sequence critical section. 3. Check that system calls are not invoked from within rseq critical sections by invoking rseq_signal() from ret_from_syscall(). With CONFIG_DEBUG_RSEQ, such behavior results in termination of the process with SIGSEGV. Signed-off-by:

Guo Ren <guoren@linux.alibaba.com>

arch/csky/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -49,6 +49,7 @@ config CSKY
		select HAVE_PERF_USER_STACK_DUMP
		select HAVE_DMA_CONTIGUOUS
		select HAVE_REGS_AND_STACK_ACCESS_API
		select HAVE_RSEQ
		select HAVE_STACKPROTECTOR
		select HAVE_SYSCALL_TRACEPOINTS
		select MAY_HAVE_SPARSE_IRQ

arch/csky/kernel/entry.S

+4 −1

Original line number	Diff line number	Diff line
		@@ -128,7 +128,10 @@ tlbop_end 1
		ENTRY(csky_systemcall)
		SAVE_ALL TRAP0_SIZE
		zero_fp

		#ifdef CONFIG_RSEQ_DEBUG
		mov a0, sp
		jbsr rseq_syscall
		#endif
		psrset ee, ie

		lrw r11, __NR_syscalls

arch/csky/kernel/signal.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -175,6 +175,8 @@ static void handle_signal(struct ksignal ksig, struct pt_regs regs)
		sigset_t *oldset = sigmask_to_save();
		int ret;

		rseq_signal_deliver(ksig, regs);

		/* Are we from a system call? */
		if (in_syscall(regs)) {
		/* Avoid additional syscall restarting via ret_from_exception */
		@@ -258,5 +260,6 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
		if (thread_info_flags & _TIF_NOTIFY_RESUME) {
		clear_thread_flag(TIF_NOTIFY_RESUME);
		tracehook_notify_resume(regs);
		rseq_handle_notify_resume(NULL, regs);
		}
		}

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