1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* 22 * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved. 23 * Copyright 2020 OmniOS Community Edition (OmniOSce) Association. 24 */ 25 26 #ifndef _COMMON_BRAND_ASM_H 27 #define _COMMON_BRAND_ASM_H 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 #ifndef lint 34 35 #include <sys/asm_linkage.h> 36 #include <sys/privregs.h> 37 #include <sys/segments.h> 38 #include "assym.h" 39 40 #endif /* lint */ 41 42 #ifdef _ASM /* The remainder of this file is only for assembly files */ 43 44 #if defined(__amd64) 45 /* 46 * Common to all 64-bit callbacks: 47 * 48 * We're running on the kernel's %gs. 49 * 50 * We return directly to userland, bypassing the _update_sregs logic, so 51 * the routine must NOT do anything that could cause a context switch. 52 * 53 * %rax - syscall number 54 * 55 * When called, all general registers, except for %r15, are as they were when 56 * the user process made the system call. %r15 is available to the callback as 57 * a scratch register. If the callback returns to the kernel path, %r15 does 58 * not have to be restored to the user value. If the callback returns to the 59 * userlevel emulation code, the callback should restore %r15 if the emulation 60 * depends on the original userlevel value. 61 * 62 * 64-BIT INTERPOSITION STACK 63 * On entry to the callback the stack looks like this: 64 * -------------------------------------- 65 * 32 | callback pointer | 66 * 24 | saved stack pointer | 67 * | 16 | lwp pointer | 68 * v 8 | user return address | 69 * 0 | BRAND_CALLBACK()'s return addr | 70 * -------------------------------------- 71 */ 72 73 #define V_COUNT 5 74 #define V_END (CLONGSIZE * 5) 75 #define V_SSP (CLONGSIZE * 3) 76 #define V_LWP (CLONGSIZE * 2) 77 #define V_URET_ADDR (CLONGSIZE * 1) 78 #define V_CB_ADDR (CLONGSIZE * 0) 79 80 #define SP_REG %rsp 81 #define SCR_REG %r15 82 #define SCR_REGB %r15b 83 #define SYSCALL_REG %rax 84 85 /* 86 * 64-BIT INT STACK 87 * For int callbacks (e.g. int91) the saved stack pointer (V_SSP) points at 88 * the state saved when we took the interrupt: 89 * -------------------------------------- 90 * | 32 | user's %ss | 91 * | 24 | user's %esp | 92 * | 16 | EFLAGS register | 93 * v 8 | user's %cs | 94 * 0 | user's %eip (user return address) | 95 * -------------------------------------- 96 */ 97 #define V_U_EIP (CLONGSIZE * 0) 98 99 #else /* !__amd64 */ 100 /* 101 * 32-BIT INTERPOSITION STACK 102 * When our syscall interposition callback entry point gets invoked the 103 * stack looks like this: 104 * -------------------------------------- 105 * | 16 | 'scratch space' | 106 * | 12 | user's %ebx | 107 * | 8 | user's %gs selector | 108 * v 4 | lwp pointer | 109 * 0 | callback wrapper return addr | 110 * -------------------------------------- 111 */ 112 113 #define V_COUNT 5 114 #define V_END (CLONGSIZE * 5) 115 #define V_U_EBX (CLONGSIZE * 3) 116 #define V_LWP (CLONGSIZE * 1) 117 #define V_CB_ADDR (CLONGSIZE * 0) 118 119 #define SP_REG %esp 120 #define SCR_REG %ebx 121 #define SCR_REGB %bl 122 #define SYSCALL_REG %eax 123 124 /* 125 * 32-BIT INT STACK 126 * For the lcall handler for 32-bit OS (i.e. xxx_brand_syscall_callback) 127 * above the stack contents common to all callbacks is the int/lcall-specific 128 * state: 129 * -------------------------------------- 130 * | 36 | user's %ss | 131 * | 32 | user's %esp | 132 * | 28 | EFLAGS register | 133 * v 24 | user's %cs | 134 * 20 | user's %eip (user return address) | 135 * -------------------------------------- 136 */ 137 #define V_U_EIP (V_END + (CLONGSIZE * 0)) 138 139 #endif /* !__amd64 */ 140 141 /* 142 * The following macros allow us to access to variables/parameters passed 143 * in on the stack. They take the following variables: 144 * sp - a register with the current stack pointer value 145 * pcnt - the number of words currently pushed onto the stack 146 * var - the variable to lookup 147 * reg - a register to read the variable into, or 148 * a register to write to the variable 149 */ 150 #define V_OFFSET(pcnt, var) \ 151 (var + (pcnt * CLONGSIZE)) 152 153 #define GET_V(sp, pcnt, var, reg) \ 154 mov V_OFFSET(pcnt, var)(sp), reg 155 156 #define SET_V(sp, pcnt, var, reg) \ 157 mov reg, V_OFFSET(pcnt, var)(sp) 158 159 #define GET_PROCP(sp, pcnt, reg) \ 160 GET_V(sp, pcnt, V_LWP, reg); /* get lwp pointer */ \ 161 mov LWP_PROCP(reg), reg /* get proc pointer */ 162 163 #define GET_P_BRAND_DATA(sp, pcnt, reg) \ 164 GET_PROCP(sp, pcnt, reg); \ 165 mov P_BRAND_DATA(reg), reg /* get p_brand_data */ 166 167 /* 168 * Each of the following macros returns to the standard syscall codepath if 169 * it detects that this process is not able, or intended, to emulate this 170 * system call. They all assume that the routine provides a 'bail-out' 171 * label of '9'. 172 */ 173 174 /* 175 * See if this process has a user-space handler registered for it. For the 176 * brand, the per-process brand data holds the address of the handler. 177 * As shown in the stack diagrams above, the callback code leaves the lwp 178 * pointer at well-defined offsets, so check if proc_data_t->X_handler is 179 * non-NULL. For each brand, the handler parameter refers to the brand's 180 * user-space handler variable name. 181 */ 182 #define CHECK_FOR_HANDLER(scr, handler) \ 183 GET_P_BRAND_DATA(SP_REG, 0, scr); /* get p_brand_data */ \ 184 cmp $0, scr; \ 185 je 9f; \ 186 cmpq $0, handler(scr); /* check handler */ \ 187 je 9f 188 189 /* 190 * If the system call number is >= 1024, then it is coming from the 191 * emulation support library. As such we should handle it natively instead 192 * of sending it back to the emulation library. 193 */ 194 #define CHECK_FOR_NATIVE(reg) \ 195 cmp $1024, reg; \ 196 jl 1f; \ 197 sub $1024, reg; \ 198 jmp 9f; \ 199 1: 200 201 /* 202 * Check to see if we want to interpose on this system call. If not, we 203 * jump back into the normal syscall path and pretend nothing happened. 204 * This macro is usable for brands which have the same number of syscalls 205 * as the base OS. 206 */ 207 #define CHECK_FOR_INTERPOSITION(emul_table, call, scr, scr_low) \ 208 cmp $NSYSCALL, call; /* is 0 <= syscall <= MAX? */ \ 209 ja 9f; /* no, take normal ret path */ \ 210 lea emul_table, scr; \ 211 /*CSTYLED*/ \ 212 mov (scr), scr; \ 213 add call, scr; \ 214 /*CSTYLED*/ \ 215 movb (scr), scr_low; \ 216 cmpb $0, scr_low; \ 217 je 9f /* no, take normal ret path */ 218 219 #define CALLBACK_PROLOGUE(emul_table, handler, call, scr, scr_low) \ 220 CHECK_FOR_HANDLER(scr, handler); \ 221 CHECK_FOR_NATIVE(call); \ 222 CHECK_FOR_INTERPOSITION(emul_table, call, scr, scr_low) 223 224 /* 225 * Rather than returning to the instruction after the syscall, we need to 226 * transfer control into the brand library's handler table at 227 * table_addr + (16 * syscall_num), thus encoding the system call number in the 228 * instruction pointer. The CALC_TABLE_ADDR macro performs that calculation. 229 * 230 * This macro assumes the syscall number is in SYSCALL_REG and it clobbers 231 * that register. It leaves the calculated handler table return address in 232 * the scratch reg. 233 */ 234 #define CALC_TABLE_ADDR(scr, handler) \ 235 GET_P_BRAND_DATA(SP_REG, 0, scr); /* get p_brand_data ptr */ \ 236 mov handler(scr), scr; /* get p_brand_data->XX_handler */ \ 237 shl $4, SYSCALL_REG; /* syscall_num * 16 */ \ 238 add SYSCALL_REG, scr /* leave return addr in scr reg. */ 239 240 #endif /* _ASM */ 241 242 #ifdef __cplusplus 243 } 244 #endif 245 246 #endif /* _COMMON_BRAND_ASM_H */ 247