1 // SPDX-License-Identifier: GPL-2.0 2 /* windows.c: Routines to deal with register window management 3 * at the C-code level. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/sched.h> 10 #include <linux/string.h> 11 #include <linux/mm.h> 12 #include <linux/smp.h> 13 14 #include <asm/cacheflush.h> 15 #include <linux/uaccess.h> 16 17 #include "kernel.h" 18 19 /* Do save's until all user register windows are out of the cpu. */ 20 void flush_user_windows(void) 21 { 22 register int ctr asm("g5"); 23 24 ctr = 0; 25 __asm__ __volatile__( 26 "\n1:\n\t" 27 "ld [%%g6 + %2], %%g4\n\t" 28 "orcc %%g0, %%g4, %%g0\n\t" 29 "add %0, 1, %0\n\t" 30 "bne 1b\n\t" 31 " save %%sp, -64, %%sp\n" 32 "2:\n\t" 33 "subcc %0, 1, %0\n\t" 34 "bne 2b\n\t" 35 " restore %%g0, %%g0, %%g0\n" 36 : "=&r" (ctr) 37 : "0" (ctr), 38 "i" ((const unsigned long)TI_UWINMASK) 39 : "g4", "cc"); 40 } 41 42 static inline void shift_window_buffer(int first_win, int last_win, struct thread_info *tp) 43 { 44 int i; 45 46 for(i = first_win; i < last_win; i++) { 47 tp->rwbuf_stkptrs[i] = tp->rwbuf_stkptrs[i+1]; 48 memcpy(&tp->reg_window[i], &tp->reg_window[i+1], sizeof(struct reg_window32)); 49 } 50 } 51 52 /* Place as many of the user's current register windows 53 * on the stack that we can. Even if the %sp is unaligned 54 * we still copy the window there, the only case that we don't 55 * succeed is if the %sp points to a bum mapping altogether. 56 * setup_frame() and do_sigreturn() use this before shifting 57 * the user stack around. Future instruction and hardware 58 * bug workaround routines will need this functionality as 59 * well. 60 */ 61 void synchronize_user_stack(void) 62 { 63 struct thread_info *tp = current_thread_info(); 64 int window; 65 66 flush_user_windows(); 67 if(!tp->w_saved) 68 return; 69 70 /* Ok, there is some dirty work to do. */ 71 for(window = tp->w_saved - 1; window >= 0; window--) { 72 unsigned long sp = tp->rwbuf_stkptrs[window]; 73 74 /* Ok, let it rip. */ 75 if (copy_to_user((char __user *) sp, &tp->reg_window[window], 76 sizeof(struct reg_window32))) 77 continue; 78 79 shift_window_buffer(window, tp->w_saved - 1, tp); 80 tp->w_saved--; 81 } 82 } 83 84 #if 0 85 /* An optimization. */ 86 static inline void copy_aligned_window(void *dest, const void *src) 87 { 88 __asm__ __volatile__("ldd [%1], %%g2\n\t" 89 "ldd [%1 + 0x8], %%g4\n\t" 90 "std %%g2, [%0]\n\t" 91 "std %%g4, [%0 + 0x8]\n\t" 92 "ldd [%1 + 0x10], %%g2\n\t" 93 "ldd [%1 + 0x18], %%g4\n\t" 94 "std %%g2, [%0 + 0x10]\n\t" 95 "std %%g4, [%0 + 0x18]\n\t" 96 "ldd [%1 + 0x20], %%g2\n\t" 97 "ldd [%1 + 0x28], %%g4\n\t" 98 "std %%g2, [%0 + 0x20]\n\t" 99 "std %%g4, [%0 + 0x28]\n\t" 100 "ldd [%1 + 0x30], %%g2\n\t" 101 "ldd [%1 + 0x38], %%g4\n\t" 102 "std %%g2, [%0 + 0x30]\n\t" 103 "std %%g4, [%0 + 0x38]\n\t" : : 104 "r" (dest), "r" (src) : 105 "g2", "g3", "g4", "g5"); 106 } 107 #endif 108 109 /* Try to push the windows in a threads window buffer to the 110 * user stack. Unaligned %sp's are not allowed here. 111 */ 112 113 void try_to_clear_window_buffer(struct pt_regs *regs, int who) 114 { 115 struct thread_info *tp = current_thread_info(); 116 int window; 117 118 flush_user_windows(); 119 for(window = 0; window < tp->w_saved; window++) { 120 unsigned long sp = tp->rwbuf_stkptrs[window]; 121 122 if ((sp & 7) || 123 copy_to_user((char __user *) sp, &tp->reg_window[window], 124 sizeof(struct reg_window32))) { 125 force_fatal_sig(SIGILL); 126 return; 127 } 128 } 129 tp->w_saved = 0; 130 } 131