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Index: head/sys/amd64/linux/linux_sysvec.c
===================================================================
--- head/sys/amd64/linux/linux_sysvec.c
+++ head/sys/amd64/linux/linux_sysvec.c
@@ -206,24 +206,45 @@
static void
linux_set_syscall_retval(struct thread *td, int error)
{
- struct trapframe *frame = td->td_frame;
+ struct trapframe *frame;
- /*
- * On Linux only %rcx and %r11 values are not preserved across
- * the syscall. So, do not clobber %rdx and %r10.
- */
- td->td_retval[1] = frame->tf_rdx;
- if (error != EJUSTRETURN)
- frame->tf_r10 = frame->tf_rcx;
+ frame = td->td_frame;
- cpu_set_syscall_retval(td, error);
+ switch (error) {
+ case 0:
+ frame->tf_rax = td->td_retval[0];
+ frame->tf_r10 = frame->tf_rcx;
+ break;
- if (__predict_false(error != 0)) {
- if (error != ERESTART && error != EJUSTRETURN)
- frame->tf_rax = linux_to_bsd_errno(error);
+ case ERESTART:
+ /*
+ * Reconstruct pc, we know that 'syscall' is 2 bytes,
+ * lcall $X,y is 7 bytes, int 0x80 is 2 bytes.
+ * We saved this in tf_err.
+ *
+ */
+ frame->tf_rip -= frame->tf_err;
+ frame->tf_r10 = frame->tf_rcx;
+ break;
+
+ case EJUSTRETURN:
+ break;
+
+ default:
+ frame->tf_rax = linux_to_bsd_errno(error);
+ frame->tf_r10 = frame->tf_rcx;
+ break;
}
- /* Restore all registers. */
+ /*
+ * Differently from FreeBSD native ABI, on Linux only %rcx
+ * and %r11 values are not preserved across the syscall.
+ * Require full context restore to get all registers except
+ * those two restored at return to usermode.
+ *
+ * XXX: Would be great to be able to avoid PCB_FULL_IRET
+ * for the error == 0 case.
+ */
set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
}

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