mach: Define MACHINE_THREAD_STATE_SETUP_CALL

The existing two macros, MACHINE_THREAD_STATE_SET_PC and
MACHINE_THREAD_STATE_SET_SP, can be used to set program counter and the
stack pointer registers in a machine-specific thread state structure.

Useful as it is, this may not be enough to set up the thread to make a
function call, because the machine-specific ABI may impose additional
requirements. In particular, x86_64 ABI requires that upon function
entry, the stack pointer is 8 less than 16-byte aligned (sp & 15 == 8).

To deal with this, introduce a new macro,
MACHINE_THREAD_STATE_SETUP_CALL (), which sets both stack and
instruction pointers, and also applies any machine-specific requirements
to make a valid function call. The default implementation simply
forwards to MACHINE_THREAD_STATE_SET_PC and MACHINE_THREAD_STATE_SET_SP,
but on x86_64 we additionally align the stack pointer.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230517191436.73636-3-bugaevc@gmail.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/sysdeps/mach/thread_state.h b/sysdeps/mach/thread_state.h
index 9fa3d4e161..431aaf82ed 100644
--- a/sysdeps/mach/thread_state.h
+++ b/sysdeps/mach/thread_state.h
@@ -38,6 +38,15 @@
 #endif
 #endif
 
+/* Set up the thread state to call the given function on the given state.
+   Dependning on architecture, this may imply more than just setting PC
+   and SP.  */
+#ifndef MACHINE_THREAD_STATE_SETUP_CALL
+#define MACHINE_THREAD_STATE_SETUP_CALL(ts, stack, size, func) \
+  (MACHINE_THREAD_STATE_SET_PC (ts, func), \
+   MACHINE_THREAD_STATE_SET_SP (ts, stack, size))
+#endif
+
 /* This copies architecture-specific bits from the current thread to the new
    thread state.  */
 #ifndef MACHINE_THREAD_STATE_FIX_NEW