Richard Henderson <richard.hender...@linaro.org> writes:
> This allows the tests generated by debian-powerpc-user-cross
> to function properly, especially tests/test-coroutine.
>
> Technically this syscall is available to both ppc32 and ppc64,
> but only ppc32 glibc actually uses it. Thus the ppc64 path is
> untested.
>
> Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
Tested-by: Alex Bennée <alex.ben...@linaro.org>
and a caveat-ed:
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
I'm confused by the lock_user_struct/unlock_user_struct which AFAICT are
basically access checks. Is there an implied locking I'm missing?
> ---
> linux-user/qemu.h | 2 ++
> linux-user/ppc/signal.c | 56 +++++++++++++++++++++++++++++++++++++++++
> linux-user/syscall.c | 6 +++++
> 3 files changed, 64 insertions(+)
>
> diff --git a/linux-user/qemu.h b/linux-user/qemu.h
> index bb85c81aa4..e0963676c7 100644
> --- a/linux-user/qemu.h
> +++ b/linux-user/qemu.h
> @@ -395,6 +395,8 @@ long do_sigreturn(CPUArchState *env);
> long do_rt_sigreturn(CPUArchState *env);
> abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong
> sp);
> int do_sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
> +abi_long do_swapcontext(CPUArchState *env, abi_ulong uold_ctx,
> + abi_ulong unew_ctx, abi_long ctx_size);
> /**
> * block_signals: block all signals while handling this guest syscall
> *
> diff --git a/linux-user/ppc/signal.c b/linux-user/ppc/signal.c
> index ef4c518f11..2ae120a2bc 100644
> --- a/linux-user/ppc/signal.c
> +++ b/linux-user/ppc/signal.c
> @@ -675,3 +675,59 @@ sigsegv:
> force_sig(TARGET_SIGSEGV);
> return -TARGET_QEMU_ESIGRETURN;
> }
> +
> +/* This syscall implements {get,set,swap}context for userland. */
> +abi_long do_swapcontext(CPUArchState *env, abi_ulong uold_ctx,
> + abi_ulong unew_ctx, abi_long ctx_size)
> +{
> + struct target_ucontext *uctx;
> + struct target_mcontext *mctx;
> +
> + /* For ppc32, ctx_size is "reserved for future use".
> + * For ppc64, we do not yet support the VSX extension.
> + */
> + if (ctx_size < sizeof(struct target_ucontext)) {
> + return -TARGET_EINVAL;
> + }
> +
> + if (uold_ctx) {
> + TaskState *ts = (TaskState *)thread_cpu->opaque;
> +
> + if (!lock_user_struct(VERIFY_WRITE, uctx, uold_ctx, 1)) {
> + return -TARGET_EFAULT;
> + }
> +
> +#ifdef TARGET_PPC64
> + mctx = &uctx->tuc_sigcontext.mcontext;
> +#else
> + /* ??? The kernel aligns the pointer down here into padding, but
> + * in setup_rt_frame we don't. Be self-compatible for now.
> + */
> + mctx = &uctx->tuc_mcontext;
> + __put_user(h2g(mctx), &uctx->tuc_regs);
> +#endif
> +
> + save_user_regs(env, mctx);
> + host_to_target_sigset(&uctx->tuc_sigmask, &ts->signal_mask);
> +
> + unlock_user_struct(uctx, uold_ctx, 1);
> + }
> +
> + if (unew_ctx) {
> + int err;
> +
> + if (!lock_user_struct(VERIFY_READ, uctx, unew_ctx, 1)) {
> + return -TARGET_EFAULT;
> + }
> + err = do_setcontext(uctx, env, 0);
> + unlock_user_struct(uctx, unew_ctx, 1);
> +
> + if (err) {
> + /* We cannot return to a partially updated context. */
> + force_sig(TARGET_SIGSEGV);
> + }
> + return -TARGET_QEMU_ESIGRETURN;
> + }
> +
> + return 0;
> +}
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 3df3bdffb2..dfc851cc35 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -12790,6 +12790,12 @@ abi_long do_syscall(void *cpu_env, int num, abi_long
> arg1,
> ret = get_errno(kcmp(arg1, arg2, arg3, arg4, arg5));
> break;
> #endif
> +#ifdef TARGET_NR_swapcontext
> + case TARGET_NR_swapcontext:
> + /* PowerPC specific. */
> + ret = do_swapcontext(cpu_env, arg1, arg2, arg3);
> + break;
> +#endif
>
> default:
> unimplemented:
--
Alex Bennée
