exceptions-sparc.c

/*
 * exceptions-sparc.c: exception support for sparc
 *
 * Authors:
 *   Mark Crichton (crichton@gimp.org)
 *   Dietmar Maurer (dietmar@ximian.com)
 *
 * (C) 2003 Ximian, Inc.
 */

#include <config.h>
#include <glib.h>
#include <signal.h>
#include <string.h>
#include <sys/ucontext.h>

#include <mono/arch/sparc/sparc-codegen.h>
#include <mono/metadata/appdomain.h>
#include <mono/metadata/tabledefs.h>
#include <mono/metadata/threads.h>
#include <mono/metadata/debug-helpers.h>
#include <mono/metadata/exception.h>
#include <mono/metadata/mono-debug.h>
#include <mono/metadata/gc-internal.h>
#include <mono/metadata/tokentype.h>

#include "mini.h"
#include "mini-sparc.h"

#ifndef REG_SP
#define REG_SP REG_O6
#endif

#define MONO_SPARC_WINDOW_ADDR(sp) ((gpointer*)(((guint8*)(sp)) + MONO_SPARC_STACK_BIAS))

/*
 * mono_arch_get_restore_context:
 *
 * Returns a pointer to a method which restores a previously saved sigcontext.
 */
gpointer
mono_arch_get_restore_context (MonoTrampInfo **info, gboolean aot)
{
	static guint32 *start;
	static int inited = 0;
	guint32 *code;

	g_assert (!aot);
	if (info)
		*info = NULL;

	if (inited)
		return start;

	code = start = mono_global_codeman_reserve (32 * sizeof (guint32));

	sparc_ldi_imm (code, sparc_o0, G_STRUCT_OFFSET (MonoContext, ip), sparc_i7);
	sparc_ldi_imm (code, sparc_o0, G_STRUCT_OFFSET (MonoContext, sp), sparc_i6);

	sparc_jmpl_imm (code, sparc_i7, 0, sparc_g0);
	/* FIXME: This does not return to the correct window */
	sparc_restore_imm (code, sparc_g0, 0, sparc_g0);

	g_assert ((code - start) < 32);

	mono_arch_flush_icache ((guint8*)start, (guint8*)code - (guint8*)start);

	inited = 1;

	return start;
}

/*
 * mono_arch_get_call_filter:
 *
 * Returns a pointer to a method which calls an exception filter. We
 * also use this function to call finally handlers (we pass NULL as 
 * @exc object in this case).
 *
 * call_filter (MonoContext *ctx, gpointer ip)
 */
gpointer
mono_arch_get_call_filter (MonoTrampInfo **info, gboolean aot)
{
	static guint32 *start;
	static int inited = 0;
	guint32 *code;
	int i;

	g_assert (!aot);
	if (info)
		*info = NULL;

	if (inited)
		return start;

	code = start = mono_global_codeman_reserve (64 * sizeof (guint32));

	/*
	 * There are two frames here:
	 * - the first frame is used by call_filter
	 * - the second frame is used to run the filter code
	 */

	/* Create first frame */
	sparc_save_imm (code, sparc_sp, -256, sparc_sp);

	sparc_mov_reg_reg (code, sparc_i1, sparc_o0);
	sparc_ldi_imm (code, sparc_i0, G_STRUCT_OFFSET (MonoContext, sp), sparc_o1);

	/* Create second frame */
	sparc_save_imm (code, sparc_sp, -256, sparc_sp);

	sparc_mov_reg_reg (code, sparc_i0, sparc_o0);
	sparc_mov_reg_reg (code, sparc_i1, sparc_o1);

	/*
	 * We need to change %fp to point to the stack frame of the method
	 * containing the filter. But changing %fp also changes the %sp of
	 * the parent frame (the first frame), so if the OS saves the first frame,
	 * it saves it to the stack frame of the method, which is not good.
	 * So flush all register windows to memory before changing %fp.
	 */
	sparc_flushw (code);

	sparc_mov_reg_reg (code, sparc_fp, sparc_o7);

	/* 
	 * Modify the second frame so it is identical to the one used in the
	 * method containing the filter.
	 */
	for (i = 0; i < 16; ++i)
		sparc_ldi_imm (code, sparc_o1, MONO_SPARC_STACK_BIAS + i * sizeof (gpointer), sparc_l0 + i);

	/* Save %fp to a location reserved in mono_arch_allocate_vars */
	sparc_sti_imm (code, sparc_o7, sparc_fp, MONO_SPARC_STACK_BIAS - sizeof (gpointer));

	/* Call the filter code, after this returns, %o0 will hold the result */
	sparc_call_imm (code, sparc_o0, 0);
	sparc_nop (code);

	/* Restore original %fp */
	sparc_ldi_imm (code, sparc_fp, MONO_SPARC_STACK_BIAS - sizeof (gpointer), sparc_fp);

	sparc_mov_reg_reg (code, sparc_o0, sparc_i0);

	/* Return to first frame */
	sparc_restore (code, sparc_g0, sparc_g0, sparc_g0);

	/* FIXME: Save locals to the stack */

	/* Return to caller */
	sparc_ret (code);
	/* Return result in delay slot */
	sparc_restore (code, sparc_o0, sparc_g0, sparc_o0);

	g_assert ((code - start) < 64);

	mono_arch_flush_icache ((guint8*)start, (guint8*)code - (guint8*)start);

	inited = 1;

	return start;
}

static void
throw_exception (MonoObject *exc, gpointer sp, gpointer ip, gboolean rethrow)
{
	MonoContext ctx;
	static void (*restore_context) (MonoContext *);
	gpointer *window;
	
	if (!restore_context)
		restore_context = mono_get_restore_context ();

	window = MONO_SPARC_WINDOW_ADDR (sp);
	ctx.sp = (gpointer*)sp;
	ctx.ip = ip;
	ctx.fp = (gpointer*)(MONO_SPARC_WINDOW_ADDR (sp) [sparc_i6 - 16]);

	if (mono_object_isinst (exc, mono_defaults.exception_class)) {
		MonoException *mono_ex = (MonoException*)exc;
		if (!rethrow)
			mono_ex->stack_trace = NULL;
	}
	mono_handle_exception (&ctx, exc, ip, FALSE);
	restore_context (&ctx);

	g_assert_not_reached ();
}

static gpointer 
get_throw_exception (gboolean rethrow)
{
	guint32 *start, *code;

	code = start = mono_global_codeman_reserve (16 * sizeof (guint32));

	sparc_save_imm (code, sparc_sp, -512, sparc_sp);

	sparc_flushw (code);
	sparc_mov_reg_reg (code, sparc_i0, sparc_o0);
	sparc_mov_reg_reg (code, sparc_fp, sparc_o1);
	sparc_mov_reg_reg (code, sparc_i7, sparc_o2);
	sparc_set (code, rethrow, sparc_o3);
	sparc_set (code, throw_exception, sparc_o7);
	sparc_jmpl (code, sparc_o7, sparc_g0, sparc_callsite);
	sparc_nop (code);

	g_assert ((code - start) <= 16);

	mono_arch_flush_icache ((guint8*)start, (guint8*)code - (guint8*)start);

	return start;
}

/**
 * mono_arch_get_throw_exception:
 *
 * Returns a function pointer which can be used to raise exceptions.
 * The returned function has the following 
 * signature: void (*func) (MonoException *exc); 
 */
gpointer
mono_arch_get_throw_exception (MonoTrampInfo **info, gboolean aot)
{
	static guint32* start;
	static int inited = 0;

	g_assert (!aot);
	if (info)
		*info = NULL;

	if (inited)
		return start;

	inited = 1;

	start = get_throw_exception (FALSE);

	return start;
}

gpointer
mono_arch_get_rethrow_exception (MonoTrampInfo **info, gboolean aot)
{
	static guint32* start;
	static int inited = 0;

	g_assert (!aot);
	if (info)
		*info = NULL;

	if (inited)
		return start;

	inited = 1;

	start = get_throw_exception (TRUE);

	return start;
}

/**
 * mono_arch_get_throw_corlib_exception:
 *
 * Returns a function pointer which can be used to raise 
 * corlib exceptions. The returned function has the following 
 * signature: void (*func) (guint32 ex_token, guint32 offset); 
 * Here, offset is the offset which needs to be substracted from the caller IP 
 * to get the IP of the throw. Passing the offset has the advantage that it 
 * needs no relocations in the caller.
 */
gpointer
mono_arch_get_throw_corlib_exception (MonoTrampInfo **info, gboolean aot)
{
	static guint32 *start;
	static int inited = 0;
	guint32 *code;
	int reg;

	g_assert (!aot);
	if (info)
		*info = NULL;

	if (inited)
		return start;

	inited = 1;
	code = start = mono_global_codeman_reserve (64 * sizeof (guint32));

#ifdef SPARCV9
	reg = sparc_g4;
#else
	reg = sparc_g1;
#endif

	sparc_mov_reg_reg (code, sparc_o7, sparc_o2);
	sparc_save_imm (code, sparc_sp, -160, sparc_sp);

	sparc_set (code, MONO_TOKEN_TYPE_DEF, sparc_o7);
	sparc_add (code, FALSE, sparc_i0, sparc_o7, sparc_o1);
	sparc_set (code, mono_defaults.exception_class->image, sparc_o0);
	sparc_set (code, mono_exception_from_token, sparc_o7);
	sparc_jmpl (code, sparc_o7, sparc_g0, sparc_callsite);
	sparc_nop (code);

	/* Return to the caller, so exception handling does not see this frame */
	sparc_restore (code, sparc_o0, sparc_g0, sparc_o0);

	/* Compute throw ip */
	sparc_sll_imm (code, sparc_o1, 2, sparc_o1);
	sparc_sub (code, 0, sparc_o2, sparc_o1, sparc_o7);

	sparc_set (code, mono_arch_get_throw_exception (NULL, FALSE), reg);
	/* Use a jmp instead of a call so o7 is preserved */
	sparc_jmpl_imm (code, reg, 0, sparc_g0);
	sparc_nop (code);

	g_assert ((code - start) < 32);

	mono_arch_flush_icache ((guint8*)start, (guint8*)code - (guint8*)start);

	return start;
}

/* mono_arch_find_jit_info:
 *
 * This function is used to gather information from @ctx. It return the 
 * MonoJitInfo of the corresponding function, unwinds one stack frame and
 * stores the resulting context into @new_ctx. It also stores a string 
 * describing the stack location into @trace (if not NULL), and modifies
 * the @lmf if necessary. @native_offset return the IP offset from the 
 * start of the function or -1 if that info is not available.
 */
gboolean
mono_arch_find_jit_info (MonoDomain *domain, MonoJitTlsData *jit_tls, 
							 MonoJitInfo *ji, MonoContext *ctx, 
							 MonoContext *new_ctx, MonoLMF **lmf,
							 mgreg_t **save_locations,
							 StackFrameInfo *frame)
{
	gpointer *window;

	memset (frame, 0, sizeof (StackFrameInfo));
	frame->ji = ji;
	frame->managed = FALSE;

	*new_ctx = *ctx;

	if (ji != NULL) {
		frame->type = FRAME_TYPE_MANAGED;

		if (!ji->method->wrapper_type || ji->method->wrapper_type == MONO_WRAPPER_DYNAMIC_METHOD)
			frame->managed = TRUE;

		if (*lmf && (MONO_CONTEXT_GET_BP (ctx) >= (gpointer)(*lmf)->ebp)) {
			/* remove any unused lmf */
			*lmf = (*lmf)->previous_lmf;
		}

		/* Restore ip and sp from the saved register window */
		window = MONO_SPARC_WINDOW_ADDR (ctx->sp);
		new_ctx->ip = window [sparc_i7 - 16];
		new_ctx->sp = (gpointer*)(window [sparc_i6 - 16]);
		new_ctx->fp = (gpointer*)(MONO_SPARC_WINDOW_ADDR (new_ctx->sp) [sparc_i6 - 16]);

		return TRUE;
	}
	else {
		if (!(*lmf))
			return FALSE;

		if (!(*lmf)->method)
			return FALSE;

		ji = mini_jit_info_table_find (domain, (gpointer)(*lmf)->ip, NULL);
		if (!ji)
			return FALSE;

		frame->ji = ji;
		frame->type = FRAME_TYPE_MANAGED_TO_NATIVE;

		new_ctx->ip = (*lmf)->ip;
		new_ctx->sp = (*lmf)->sp;
		new_ctx->fp = (*lmf)->ebp;

		*lmf = (*lmf)->previous_lmf;

		return TRUE;
	}
}

gboolean
mono_arch_has_unwind_info (gconstpointer addr)
{
	return FALSE;
}

#ifdef __linux__

gboolean
mono_arch_handle_exception (void *sigctx, gpointer obj, gboolean test_only)
{
       MonoContext mctx;
       struct sigcontext *sc = sigctx;
       gpointer *window;

#ifdef SPARCV9
       mctx.ip = (gpointer) sc->sigc_regs.tpc;
       mctx.sp = (gpointer) sc->sigc_regs.u_regs[14];
#else
       mctx.ip = (gpointer) sc->si_regs.pc;
       mctx.sp = (gpointer) sc->si_regs.u_regs[14];
#endif

       window = (gpointer*)(((guint8*)mctx.sp) + MONO_SPARC_STACK_BIAS);
       mctx.fp = window [sparc_fp - 16];

       mono_handle_exception (&mctx, obj, mctx.ip, test_only);

#ifdef SPARCV9
       sc->sigc_regs.tpc = (unsigned long) mctx.ip;
       sc->sigc_regs.tnpc = (unsigned long) (mctx.ip + 4);
       sc->sigc_regs.u_regs[14] = (unsigned long) mctx.sp;
#else
       sc->si_regs.pc = (unsigned long) mctx.ip;
       sc->si_regs.npc = (unsigned long) (mctx.ip + 4);
       sc->si_regs.u_regs[14] = (unsigned long) mctx.sp;
#endif

       window = (gpointer*)(((guint8*)mctx.sp) + MONO_SPARC_STACK_BIAS);
       window [sparc_fp - 16] = mctx.fp;

       return TRUE;
}

gpointer
mono_arch_ip_from_context (void *sigctx)
{
       struct sigcontext *sc = sigctx;
       gpointer *ret;

#ifdef SPARCV9
       ret = (gpointer) sc->sigc_regs.tpc;
#else
       ret = (gpointer) sc->si_regs.pc;
#endif

       return ret;
}

#else /* !__linux__ */

gboolean
mono_arch_handle_exception (void *sigctx, gpointer obj, gboolean test_only)
{
	MonoContext mctx;
	ucontext_t *ctx = (ucontext_t*)sigctx;
	gpointer *window;

	/*
	 * Access to the machine state using the ucontext_t parameter is somewhat
	 * under documented under solaris. The code below seems to work under
	 * Solaris 9.
	 */
	g_assert (!ctx->uc_mcontext.gwins);

	mctx.ip = ctx->uc_mcontext.gregs [REG_PC];
	mctx.sp = ctx->uc_mcontext.gregs [REG_SP];
	window = (gpointer*)(((guint8*)mctx.sp) + MONO_SPARC_STACK_BIAS);
	mctx.fp = window [sparc_fp - 16];

	mono_handle_exception (&mctx, obj, mctx.ip, test_only);
	
	/* We can't use restore_context to return from a signal handler */
	ctx->uc_mcontext.gregs [REG_PC] = mctx.ip;
	ctx->uc_mcontext.gregs [REG_nPC] = mctx.ip + 4;
	ctx->uc_mcontext.gregs [REG_SP] = mctx.sp;
	window = (gpointer*)(((guint8*)mctx.sp) + MONO_SPARC_STACK_BIAS);
	window [sparc_fp - 16] = mctx.fp;

	return TRUE;
}

gpointer
mono_arch_ip_from_context (void *sigctx)
{
	ucontext_t *ctx = (ucontext_t*)sigctx;
	return (gpointer)ctx->uc_mcontext.gregs [REG_PC];
}

#endif