1 /* 2 * Copyright (c) 1992 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This software was developed by the Computer Systems Engineering group 6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 7 * contributed to Berkeley. 8 * 9 * All advertising materials mentioning features or use of this software 10 * must display the following acknowledgement: 11 * This product includes software developed by the University of 12 * California, Lawrence Berkeley Laboratory. 13 * 14 * %sccs.include.redist.c% 15 * 16 * @(#)pcb.h 7.3 (Berkeley) 04/20/93 17 * 18 * from: $Header: pcb.h,v 1.6 92/11/26 02:04:39 torek Exp $ 19 */ 20 21 #include <machine/reg.h> 22 23 #ifdef notyet 24 #define PCB_MAXWIN 32 /* architectural limit */ 25 #else 26 #define PCB_MAXWIN 8 /* worried about u area sizes ... */ 27 #endif 28 29 /* 30 * SPARC Process Control Block. 31 * 32 * pcb_uw is positive if there are any user windows that are 33 * are currently in the CPU windows rather than on the user 34 * stack. Whenever we are running in the kernel with traps 35 * enabled, we decrement pcb_uw for each ``push'' of a CPU 36 * register window into the stack, and we increment it for 37 * each ``pull'' from the stack into the CPU. (If traps are 38 * disabled, or if we are in user mode, pcb_uw is junk.) 39 * 40 * To ease computing pcb_uw on traps from user mode, we keep track 41 * of the log base 2 of the single bit that is set in %wim. 42 * 43 * If an overflow occurs while the associated user stack pages 44 * are invalid (paged out), we have to store the registers 45 * in a page that is locked in core while the process runs, 46 * i.e., right here in the pcb. We also need the stack pointer 47 * for the last such window (but only the last, as the others 48 * are in each window) and the count of windows saved. We 49 * cheat by having a whole window structure for that one %sp. 50 * Thus, to save window pcb_rw[i] to memory, we write it at 51 * pcb_rw[i + 1].rw_in[6]. 52 * 53 * pcb_nsaved has three `kinds' of values. If 0, it means no 54 * registers are in the PCB (though if pcb_uw is positive, 55 * there may be the next time you look). If positive, it means 56 * there are no user registers in the CPU, but there are some 57 * saved in pcb_rw[]. As a special case, traps that needed 58 * assistance to pull user registers from the stack also store 59 * the registers in pcb_rw[], and set pcb_nsaved to -1. This 60 * special state is normally short-term: it can only last until the 61 * trap returns, and it can never persist across entry to user code. 62 */ 63 struct pcb { 64 int pcb_sp; /* sp (%o6) when swtch() was called */ 65 int pcb_pc; /* pc (%o7) when swtch() was called */ 66 int pcb_psr; /* %psr when swtch() was called */ 67 68 caddr_t pcb_onfault; /* for copyin/out */ 69 70 int pcb_uw; /* user windows inside CPU */ 71 int pcb_wim; /* log2(%wim) */ 72 int pcb_nsaved; /* number of windows saved in pcb */ 73 74 #ifdef notdef 75 int pcb_winof; /* number of window overflow traps */ 76 int pcb_winuf; /* number of window underflow traps */ 77 #endif 78 int pcb_pad; /* pad to doubleword boundary */ 79 80 /* the following MUST be aligned on a doubleword boundary */ 81 struct rwindow pcb_rw[PCB_MAXWIN]; /* saved windows */ 82 }; 83 84 /* 85 * The pcb is augmented with machine-dependent additional data for 86 * core dumps. Note that the trapframe here is a copy of the one 87 * from the top of the kernel stack (included here so that the kernel 88 * stack itself need not be dumped). 89 */ 90 struct md_coredump { 91 struct trapframe md_tf; 92 struct fpstate md_fpstate; 93 }; 94 95 #ifdef KERNEL 96 extern struct pcb *cpcb; 97 #endif /* KERNEL */ 98