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csky: Add support for restartable sequence

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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>
This commit is contained in:
Guo Ren 2019-11-05 09:58:33 +08:00
parent bfe47f358a
commit 9866d141a0
3 changed files with 8 additions and 1 deletions
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1
arch/csky/Kconfig
View File

@ -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

5
arch/csky/kernel/entry.S
View File

@ -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

3
arch/csky/kernel/signal.c
View File

@ -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);
}
}