print kernel stacktrace for exceptions in kernel

fpu alignment check feature, checksum feature

common/include/arch/i386/archtypes.h

@@ -37,6 +37,7 @@ struct fpu_state_s {
 	/* fpu_image includes 512 bytes of image itself and
 	 * additional 15 bytes required for manual 16-byte alignment. */
 	char fpu_image[527];
+	u32_t checksum;
 };
 
 #define INMEMORY(p) (!p->p_seg.p_cr3 || get_cpulocal_var(ptproc) == p)

kernel/Makefile

@@ -14,7 +14,7 @@ SRCS += smp.c
 .endif
 
 DPADD+=	${LIBTIMERS} ${LIBSYS} ${LIBEXEC}
-LDADD+=	-ltimers -lsys -lexec
+LDADD+=	-ltimers -lsys -lexec -lz
 
 CFLAGS += -D__kernel__
 

kernel/arch/i386/arch_system.c

@@ -58,6 +58,27 @@ FORWARD _PROTOTYPE( void ser_dump_proc_cpu, (void));
 FORWARD _PROTOTYPE( void ser_init, (void));
 #endif
 
+PRIVATE u32_t fpusum(struct proc *p)
+{
+	void *save_area = p->p_fpu_state.fpu_save_area_p;
+	return crc32(0, save_area, FPU_XFP_SIZE);
+}
+
+PUBLIC void fpu_makechecksum(struct proc *p)
+{
+	p->p_fpu_state.checksum = fpusum(p);
+}
+
+PUBLIC void fpu_verifychecksum(struct proc *p)
+{
+	static int n;
+	n++;
+	if(p->p_fpu_state.checksum != fpusum(p)) {
+		printf("%d / %s fpu state broken!", p->p_endpoint, p->p_name);
+		util_stacktrace();
+	}
+}
+
 PUBLIC __dead void arch_monitor(void)
 {
 	monitor();
@@ -252,16 +273,23 @@ PUBLIC void fpu_init(void)
 
 PUBLIC void save_local_fpu(struct proc *pr)
 {
+	static int n;
+	phys_bytes save_area = (phys_bytes) pr->p_fpu_state.fpu_save_area_p;
 	if(!is_fpu())
 		return;
 
+	/* save area must be 16-byte aligned */
+	assert(!(save_area % FPUALIGN));
+
 	/* Save changed FPU context. */
 	if(osfxsr_feature) {
-		fxsave(pr->p_fpu_state.fpu_save_area_p);
+		fxsave(save_area);
 		fninit();
 	} else {
-		fnsave(pr->p_fpu_state.fpu_save_area_p);
+		fnsave(save_area);
 	}
+
+	fpu_makechecksum(pr);
 }
 
 PUBLIC void save_fpu(struct proc *pr)
@@ -304,10 +332,14 @@ PUBLIC void restore_fpu(struct proc *pr)
 		fninit();
 		pr->p_misc_flags |= MF_FPU_INITIALIZED;
 	} else {
+		phys_bytes save_area = (phys_bytes) pr->p_fpu_state.fpu_save_area_p;
+		/* save area must be 16-byte aligned */
+		assert(!(save_area % FPUALIGN));
+		fpu_verifychecksum(pr);
 		if(osfxsr_feature) {
-			fxrstor(pr->p_fpu_state.fpu_save_area_p);
+			fxrstor(save_area);
 		} else {
-			frstor(pr->p_fpu_state.fpu_save_area_p);
+			frstor(save_area);
 		}
 	}
 }

kernel/arch/i386/include/arch_proto.h

@@ -95,10 +95,10 @@ _PROTOTYPE( void ia32_msr_read, (u32_t reg, u32_t * hi, u32_t * lo)	);
 _PROTOTYPE( void ia32_msr_write, (u32_t reg, u32_t hi, u32_t lo)	);
 _PROTOTYPE( void fninit, (void));
 _PROTOTYPE( void clts, (void));
-_PROTOTYPE( void fxsave, (void *));
-_PROTOTYPE( void fnsave, (void *));
-_PROTOTYPE( void fxrstor, (void *));
-_PROTOTYPE( void frstor, (void *));
+_PROTOTYPE( void fxsave, (vir_bytes));
+_PROTOTYPE( void fnsave, (vir_bytes));
+_PROTOTYPE( void fxrstor, (vir_bytes));
+_PROTOTYPE( void frstor, (vir_bytes));
 _PROTOTYPE( unsigned short fnstsw, (void));
 _PROTOTYPE( void fnstcw, (unsigned short* cw));
 

kernel/arch/i386/sconst.h

@@ -28,7 +28,7 @@
 	SSREG = SPREG+W
 	P_STACKTOP = SSREG+W
 	FP_SAVE_AREA_P = P_STACKTOP
-	P_LDT_SEL = FP_SAVE_AREA_P + 532
+	P_LDT_SEL = FP_SAVE_AREA_P + 536
 	P_CR3 = P_LDT_SEL+W
 	P_CR3_V = P_CR3+4
 	P_LDT = P_CR3_V+W

kernel/debug.h

@@ -37,6 +37,8 @@
  */
 #define DEBUG_RACE			0
 
+#define DEBUG_FPUCHECK			1
+
 /* DEBUG_DUMPIPC dumps all IPC to serial; due to the amount of logging it is 
  * strongly recommended to set "ctty 0" in the boot monitor and run inside a 
  * virtual machine if you enable this; on the hardware it would take forever 

kernel/proc.c

@@ -257,6 +257,10 @@ PUBLIC void switch_to_user(void)
 	int tlb_must_refresh = 0;
 #endif
 
+	char buf[100];
+	u32_t c;
+	c = crc32(0, buf, 100);
+
 	p = get_cpulocal_var(proc_ptr);
 	/*
 	 * if the current process is still runnable check the misc flags and let

kernel/proto.h

@@ -223,6 +223,9 @@ _PROTOTYPE( int copy_msg_to_user, (struct proc * p, message * src,
 _PROTOTYPE(void switch_address_space, (struct proc * p));
 _PROTOTYPE(void release_address_space, (struct proc *pr));
 
+_PROTOTYPE(void fpu_makechecksum, (struct proc *p));
+_PROTOTYPE(void fpu_verifychecksum, (struct proc *p));
+
 _PROTOTYPE(void enable_fpu_exception, (void));
 _PROTOTYPE(void disable_fpu_exception, (void));
 _PROTOTYPE(void release_fpu, (struct proc * p));

kernel/system/do_fork.c

@@ -65,10 +65,13 @@ PUBLIC int do_fork(struct proc * caller, message * m_ptr)
 #if (_MINIX_CHIP == _CHIP_INTEL)
   rpc->p_seg.p_ldt_sel = old_ldt_sel;	/* restore descriptors */
   rpc->p_fpu_state.fpu_save_area_p = old_fpu_save_area_p;
-  if(proc_used_fpu(rpp))
+  if(proc_used_fpu(rpp)) {
+  	fpu_verifychecksum(rpp);
 	memcpy(rpc->p_fpu_state.fpu_save_area_p,
 	       rpp->p_fpu_state.fpu_save_area_p,
 	       FPU_XFP_SIZE);
+  	fpu_verifychecksum(rpc);
+  }
 #endif
   if(++gen >= _ENDPOINT_MAX_GENERATION)	/* increase generation */
 	gen = 1;			/* generation number wraparound */

kernel/system/do_mcontext.c

@@ -86,6 +86,7 @@ PUBLIC int do_setmcontext(struct proc * caller, message * m_ptr)
 	rp->p_misc_flags |= MF_FPU_INITIALIZED;
 	memcpy(rp->p_fpu_state.fpu_save_area_p, &(mc.mc_fpu_state),
 								FPU_XFP_SIZE);
+	fpu_makechecksum(rp);
   } else
 	rp->p_misc_flags &= ~MF_FPU_INITIALIZED;
   /* force reloading FPU in either case */

kernel/system/do_sigreturn.c

@@ -56,8 +56,10 @@ PUBLIC int do_sigreturn(struct proc * caller, message * m_ptr)
 #if (_MINIX_CHIP == _CHIP_INTEL)
   if(sc.sc_flags & MF_FPU_INITIALIZED)
   {
+	fpu_verifychecksum(rp);
 	memcpy(rp->p_fpu_state.fpu_save_area_p, &sc.sc_fpu_state,
 		FPU_XFP_SIZE);
+	fpu_makechecksum(rp);
 	rp->p_misc_flags |=  MF_FPU_INITIALIZED; /* Restore math usage flag. */
 	/* force reloading FPU */
 	release_fpu(rp);