FP emulator patch

diff -u -r1.36 signal.c
@@ -220,6 +220,8 @@
 
 	err |= __get_user(owned_fp, &sc->sc_ownedfp);
 	if (owned_fp) {
+		if (last_task_used_math && (last_task_used_math != current))
+			last_task_used_math->thread.cp0_status &= ~ST0_CU1;
 		err |= restore_fp_context(sc);
 		last_task_used_math = current;
 	}

@@ -353,12 +355,11 @@
 	owned_fp = (current == last_task_used_math);
 	err |= __put_user(owned_fp, &sc->sc_ownedfp);
 
-	if (current->used_math) {	/* fp is active.  */
+	if (owned_fp) { /* fp is active.  */
 		set_cp0_status(ST0_CU1);
 		err |= save_fp_context(sc);
 		last_task_used_math = NULL;
 		regs->cp0_status &= ~ST0_CU1;
-		current->used_math = 0;
 	}
 
 	return err;

@@ -375,6 +376,13 @@
 	/* Default to using normal stack */
 	sp = regs->regs[29];
 
+	/* 
+	 * FPU emulator may have it's own trampoline active just
+	 * above the user stack, 16-bytes before the next lowest
+	 * 16 byte boundary.  Try to avoid trashing it.
+	 */
+	sp -= 32;
+
 	/* This is the X/Open sanctioned signal stack switching.  */
 	if ((ka->sa.sa_flags & SA_ONSTACK) && ! on_sig_stack(sp))
                 sp = current->sas_ss_sp + current->sas_ss_size;

@@ -435,7 +443,7 @@
 
 #if DEBUG_SIG
 	printk("SIG deliver (%s:%d): sp=0x%p pc=0x%p ra=0x%p\n",
-	       current->comm, current->pid, frame, regs->cp0_epc, frame->code);
+	       current->comm, current->pid, frame, regs->cp0_epc, frame->sf_code);
 #endif
         return;
 

diff -u -r1.12 unaligned.c
@@ -365,15 +365,12 @@
 		return;
 	}
 
-	die_if_kernel ("Unhandled kernel unaligned access", regs);
 	send_sig(SIGSEGV, current, 1);
 	return;
 sigbus:
-	die_if_kernel ("Unhandled kernel unaligned access", regs);
 	send_sig(SIGBUS, current, 1);
 	return;
 sigill:
-	die_if_kernel ("Unhandled kernel unaligned access or invalid instruction", regs);
 	send_sig(SIGILL, current, 1);
 	return;
 }

@@ -391,11 +388,10 @@
 	 * of the CPU after executing the instruction
 	 * in the delay slot of an emulated branch.
 	 */
+	/* Terminate if exception was recognized as a delay slot return */
+	if(do_dsemulret(regs)) return;
 
-	if ((unsigned long)regs->cp0_epc == current->thread.dsemul_aerpc) {
-		do_dsemulret(regs);
-		return;
-	}
+	/* Otherwise handle as normal */
 
 	/*
 	 * Did we catch a fault trying to load an instruction?

@@ -417,7 +413,6 @@
 	return;
 
 sigbus:
-	die_if_kernel ("Kernel unaligned instruction access", regs);
 	force_sig(SIGBUS, current);
 
 	return;

165 lines not on this page · raw message

diff -u -r1.3 kernel_linkage.c
@@ -3,7 +3,7 @@
  *  arch/mips/math_emu/kernel_linkage.c
  *
  *  Kevin D. Kissell, kevink@mips and Carsten Langgaard, [email protected]
- *  Copyright (C) 2000 MIPS Technologies, Inc.  All rights reserved.
+ *  Copyright (C) 2000-2001 MIPS Technologies, Inc.  All rights reserved.
  *
  * ########################################################################
  *

@@ -45,7 +45,7 @@
  
 	if (first) {
 		first = 0;
-		printk("Algorithmics/MIPS FPU Emulator v1.4\n");
+		printk("Algorithmics/MIPS FPU Emulator v1.5\n");
 	}
 
 	current->thread.fpu.soft.sr = 0;

diff -u -r1.16 offset.c
@@ -121,10 +121,6 @@
 	       thread.irix_trampoline);
 	offset("#define THREAD_OLDCTX  ", struct task_struct, \
 	       thread.irix_oldctx);
-	offset("#define THREAD_DSEEPC  ", struct task_struct, \
-	       thread.dsemul_epc);
-	offset("#define THREAD_DSEAERPC ", struct task_struct, \
-	       thread.dsemul_aerpc);
 	linefeed;
 }
 

diff -u -r1.37 processor.h
@@ -151,21 +151,6 @@
 	mm_segment_t current_ds;
 	unsigned long irix_trampoline;  /* Wheee... */
 	unsigned long irix_oldctx;
-
-	/*
-	 * These are really only needed if the full FPU emulator is configured.
-	 * Would be made conditional on MIPS_FPU_EMULATOR if it weren't for the
-	 * fact that having offset.h rebuilt differently for different config
-	 * options would be asking for trouble.
-	 *
-	 * Saved EPC during delay-slot emulation (see math-emu/cp1emu.c)
-	 */
-	unsigned long dsemul_epc;
-
-	/*
-	 * Pointer to instruction used to induce address error
-	 */
-	unsigned long dsemul_aerpc;
 };
 
 #endif /* !defined (_LANGUAGE_ASSEMBLY) */

@@ -195,11 +180,6 @@
 	 * For now the default is to fix address errors \
 	 */ \
 	MF_FIXADE, { 0 }, 0, 0, \
-	/* \
-	 * dsemul_epc and dsemul_aerpc should never be used uninitialized, \
-	 * but... \
-	 */ \
-	0 ,0 \
 }
 
 #ifdef __KERNEL__

@@ -235,8 +215,8 @@
  * Do necessary setup to start up a newly executed thread.
  */
 #define start_thread(regs, new_pc, new_sp) do {				\
-	/* New thread looses kernel privileges. */			\
-	regs->cp0_status = (regs->cp0_status & ~(ST0_CU0|ST0_KSU)) | KU_USER;\
+	/* New thread loses kernel and FPU privileges. */               \
+        regs->cp0_status = (regs->cp0_status & ~(ST0_CU0|ST0_KSU|ST0_CU1)) | KU_USER;\
 	regs->cp0_epc = new_pc;						\
 	regs->regs[29] = new_sp;					\
 	current->thread.current_ds = USER_DS;				\

diff -ur linux.sgi/arch/mips/kernel/signal.c linux/arch/mips/kernel/signal.c
@@ -350,11 +350,18 @@
 	err |= __put_user(regs->cp0_cause, &sc->sc_cause);
 	err |= __put_user(regs->cp0_badvaddr, &sc->sc_badvaddr);
 
-	owned_fp = (current == last_task_used_math);
+	/* restore_sigcontext must restore the fp context even if this
+	   process was not last_task_used_math. */
+	owned_fp = current->used_math;
 	err |= __put_user(owned_fp, &sc->sc_ownedfp);
 
 	if (current->used_math) {	/* fp is active.  */
+#if 0
+		/* Do not set CU1 here.  If this process does not
+		   owned fp, save_fp_context causes lazy_fpu_switch
+		   (and fp-owner's context will saved). */
 		set_cp0_status(ST0_CU1);
+#endif
 		err |= save_fp_context(sc);
 		last_task_used_math = NULL;
 		regs->cp0_status &= ~ST0_CU1;

diff -ur linux.sgi/arch/mips/math-emu/cp1emu.c linux/arch/mips/math-emu/cp1emu.c
@@ -686,7 +686,7 @@
 					 * branch likely nullifies dslot if not
 					 * taken
 					 */
-					xcp->cp0_epc += 4;
+					contpc += 4;
 					/* else continue & execute dslot as normal insn */
 			}
 			break;