[PATCH] riscv: signal: handle syscall restart before get_signal

[patchwork-bot+linux-riscv at kernel.org]

Hello:

This patch was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer at rivosinc.com>:

On Thu,  3 Aug 2023 15:44:54 -0700 you wrote:
> In the current riscv implementation, blocking syscalls like read() may
> not correctly restart after being interrupted by ptrace. This problem
> arises when the syscall restart process in arch_do_signal_or_restart()
> is bypassed due to changes to the regs->cause register, such as an
> ebreak instruction.
> 
> Steps to reproduce:
> 1. Interrupt the tracee process with PTRACE_SEIZE & PTRACE_INTERRUPT.
> 2. Backup original registers and instruction at new_pc.
> 3. Change pc to new_pc, and inject an instruction (like ebreak) to this
>    address.
> 4. Resume with PTRACE_CONT and wait for the process to stop again after
>    executing ebreak.
> 5. Restore original registers and instructions, and detach from the
>    tracee process.
> 6. Now the read() syscall in tracee will return -1 with errno set to
>    ERESTARTSYS.
> 
> [...]

Here is the summary with links:
  - riscv: signal: handle syscall restart before get_signal
    https://git.kernel.org/riscv/c/ce4f78f1b53d

You are awesome, thank you!
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