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