| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* | 
|  | 2 | * Linux/PA-RISC Project (http://www.parisc-linux.org/) | 
|  | 3 | * | 
|  | 4 | * System call entry code Copyright (c) Matthew Wilcox 1999 <willy@bofh.ai> | 
|  | 5 | * Licensed under the GNU GPL. | 
|  | 6 | * thanks to Philipp Rumpf, Mike Shaver and various others | 
|  | 7 | * sorry about the wall, puffin.. | 
|  | 8 | */ | 
|  | 9 |  | 
|  | 10 | #include <asm/offsets.h> | 
|  | 11 | #include <asm/unistd.h> | 
|  | 12 | #include <asm/errno.h> | 
|  | 13 | #include <asm/psw.h> | 
|  | 14 | #include <asm/thread_info.h> | 
|  | 15 |  | 
|  | 16 | #include <asm/assembly.h> | 
|  | 17 | #include <asm/processor.h> | 
|  | 18 |  | 
|  | 19 | /* We fill the empty parts of the gateway page with | 
|  | 20 | * something that will kill the kernel or a | 
|  | 21 | * userspace application. | 
|  | 22 | */ | 
|  | 23 | #define KILL_INSN	break	0,0 | 
|  | 24 |  | 
|  | 25 | #include <linux/config.h> /* for CONFIG_SMP */ | 
|  | 26 |  | 
|  | 27 | #ifdef __LP64__ | 
|  | 28 | .level          2.0w | 
|  | 29 | #else | 
|  | 30 | .level		1.1 | 
|  | 31 | #endif | 
|  | 32 |  | 
|  | 33 | #ifndef __LP64__ | 
|  | 34 | .macro fixup_branch,lbl | 
|  | 35 | b	    \lbl | 
|  | 36 | .endm | 
|  | 37 | #else | 
|  | 38 | .macro fixup_branch,lbl | 
|  | 39 | ldil	    L%\lbl, %r1 | 
|  | 40 | ldo	    R%\lbl(%r1), %r1 | 
|  | 41 | bv,n        %r0(%r1) | 
|  | 42 | .endm | 
|  | 43 | #endif | 
|  | 44 |  | 
|  | 45 | .text | 
|  | 46 |  | 
|  | 47 | .import syscall_exit,code | 
|  | 48 | .import syscall_exit_rfi,code | 
|  | 49 | .export linux_gateway_page | 
|  | 50 |  | 
|  | 51 | /* Linux gateway page is aliased to virtual page 0 in the kernel | 
|  | 52 | * address space. Since it is a gateway page it cannot be | 
|  | 53 | * dereferenced, so null pointers will still fault. We start | 
|  | 54 | * the actual entry point at 0x100. We put break instructions | 
|  | 55 | * at the beginning of the page to trap null indirect function | 
|  | 56 | * pointers. | 
|  | 57 | */ | 
|  | 58 |  | 
|  | 59 | .align 4096 | 
|  | 60 | linux_gateway_page: | 
|  | 61 |  | 
|  | 62 | /* ADDRESS 0x00 to 0xb0 = 176 bytes / 4 bytes per insn = 44 insns */ | 
|  | 63 | .rept 44 | 
|  | 64 | KILL_INSN | 
|  | 65 | .endr | 
|  | 66 |  | 
|  | 67 | /* ADDRESS 0xb0 to 0xb4, lws uses 1 insns for entry */ | 
|  | 68 | /* Light-weight-syscall entry must always be located at 0xb0 */ | 
|  | 69 | /* WARNING: Keep this number updated with table size changes */ | 
|  | 70 | #define __NR_lws_entries (2) | 
|  | 71 |  | 
|  | 72 | lws_entry: | 
|  | 73 | /* Unconditional branch to lws_start, located on the | 
|  | 74 | same gateway page */ | 
|  | 75 | b,n	lws_start | 
|  | 76 |  | 
|  | 77 | /* Fill from 0xb4 to 0xe0 */ | 
|  | 78 | .rept 11 | 
|  | 79 | KILL_INSN | 
|  | 80 | .endr | 
|  | 81 |  | 
|  | 82 | /* This function MUST be located at 0xe0 for glibc's threading | 
|  | 83 | mechanism to work. DO NOT MOVE THIS CODE EVER! */ | 
|  | 84 | set_thread_pointer: | 
|  | 85 | gate	.+8, %r0		/* increase privilege */ | 
|  | 86 | depi	3, 31, 2, %r31		/* Ensure we return into user mode. */ | 
|  | 87 | be	0(%sr7,%r31)		/* return to user space */ | 
|  | 88 | mtctl	%r26, %cr27		/* move arg0 to the control register */ | 
|  | 89 |  | 
|  | 90 | /* Increase the chance of trapping if random jumps occur to this | 
|  | 91 | address, fill from 0xf0 to 0x100 */ | 
|  | 92 | .rept 4 | 
|  | 93 | KILL_INSN | 
|  | 94 | .endr | 
|  | 95 |  | 
|  | 96 | /* This address must remain fixed at 0x100 for glibc's syscalls to work */ | 
|  | 97 | .align 256 | 
|  | 98 | linux_gateway_entry: | 
|  | 99 | gate	.+8, %r0			/* become privileged */ | 
|  | 100 | mtsp	%r0,%sr4			/* get kernel space into sr4 */ | 
|  | 101 | mtsp	%r0,%sr5			/* get kernel space into sr5 */ | 
|  | 102 | mtsp	%r0,%sr6			/* get kernel space into sr6 */ | 
|  | 103 | mfsp    %sr7,%r1                        /* save user sr7 */ | 
|  | 104 | mtsp    %r1,%sr3                        /* and store it in sr3 */ | 
|  | 105 |  | 
|  | 106 | #ifdef __LP64__ | 
|  | 107 | /* for now we can *always* set the W bit on entry to the syscall | 
|  | 108 | * since we don't support wide userland processes.  We could | 
|  | 109 | * also save the current SM other than in r0 and restore it on | 
|  | 110 | * exit from the syscall, and also use that value to know | 
|  | 111 | * whether to do narrow or wide syscalls. -PB | 
|  | 112 | */ | 
|  | 113 | ssm	PSW_SM_W, %r1 | 
|  | 114 | extrd,u	%r1,PSW_W_BIT,1,%r1 | 
|  | 115 | /* sp must be aligned on 4, so deposit the W bit setting into | 
|  | 116 | * the bottom of sp temporarily */ | 
|  | 117 | or,ev	%r1,%r30,%r30 | 
|  | 118 | b,n	1f | 
|  | 119 | /* The top halves of argument registers must be cleared on syscall | 
|  | 120 | * entry from narrow executable. | 
|  | 121 | */ | 
|  | 122 | depdi	0, 31, 32, %r26 | 
|  | 123 | depdi	0, 31, 32, %r25 | 
|  | 124 | depdi	0, 31, 32, %r24 | 
|  | 125 | depdi	0, 31, 32, %r23 | 
|  | 126 | depdi	0, 31, 32, %r22 | 
|  | 127 | depdi	0, 31, 32, %r21 | 
|  | 128 | 1: | 
|  | 129 | #endif | 
|  | 130 | mfctl   %cr30,%r1 | 
|  | 131 | xor     %r1,%r30,%r30                   /* ye olde xor trick */ | 
|  | 132 | xor     %r1,%r30,%r1 | 
|  | 133 | xor     %r1,%r30,%r30 | 
|  | 134 |  | 
|  | 135 | ldo     THREAD_SZ_ALGN+FRAME_SIZE(%r30),%r30  /* set up kernel stack */ | 
|  | 136 |  | 
|  | 137 | /* N.B.: It is critical that we don't set sr7 to 0 until r30 | 
|  | 138 | *       contains a valid kernel stack pointer. It is also | 
|  | 139 | *       critical that we don't start using the kernel stack | 
|  | 140 | *       until after sr7 has been set to 0. | 
|  | 141 | */ | 
|  | 142 |  | 
|  | 143 | mtsp	%r0,%sr7			/* get kernel space into sr7 */ | 
|  | 144 | STREGM	%r1,FRAME_SIZE(%r30)		/* save r1 (usp) here for now */ | 
|  | 145 | mfctl	%cr30,%r1			/* get task ptr in %r1 */ | 
|  | 146 | LDREG	TI_TASK(%r1),%r1 | 
|  | 147 |  | 
|  | 148 | /* Save some registers for sigcontext and potential task | 
|  | 149 | switch (see entry.S for the details of which ones are | 
|  | 150 | saved/restored).  TASK_PT_PSW is zeroed so we can see whether | 
|  | 151 | a process is on a syscall or not.  For an interrupt the real | 
|  | 152 | PSW value is stored.  This is needed for gdb and sys_ptrace. */ | 
|  | 153 | STREG	%r0,  TASK_PT_PSW(%r1) | 
|  | 154 | STREG	%r2,  TASK_PT_GR2(%r1)		/* preserve rp */ | 
|  | 155 | STREG	%r19, TASK_PT_GR19(%r1) | 
|  | 156 |  | 
|  | 157 | LDREGM	-FRAME_SIZE(%r30), %r2		/* get users sp back */ | 
|  | 158 | #ifdef __LP64__ | 
|  | 159 | extrd,u	%r2,63,1,%r19			/* W hidden in bottom bit */ | 
|  | 160 | #if 0 | 
|  | 161 | xor	%r19,%r2,%r2			/* clear bottom bit */ | 
|  | 162 | depd,z	%r19,1,1,%r19 | 
|  | 163 | std	%r19,TASK_PT_PSW(%r1) | 
|  | 164 | #endif | 
|  | 165 | #endif | 
|  | 166 | STREG	%r2,  TASK_PT_GR30(%r1)		/* ... and save it */ | 
|  | 167 |  | 
|  | 168 | STREG	%r20, TASK_PT_GR20(%r1) | 
|  | 169 | STREG	%r21, TASK_PT_GR21(%r1) | 
|  | 170 | STREG	%r22, TASK_PT_GR22(%r1) | 
|  | 171 | STREG	%r23, TASK_PT_GR23(%r1)		/* 4th argument */ | 
|  | 172 | STREG	%r24, TASK_PT_GR24(%r1)		/* 3rd argument */ | 
|  | 173 | STREG	%r25, TASK_PT_GR25(%r1)		/* 2nd argument */ | 
|  | 174 | STREG	%r26, TASK_PT_GR26(%r1)	 	/* 1st argument */ | 
|  | 175 | STREG	%r27, TASK_PT_GR27(%r1)		/* user dp */ | 
|  | 176 | STREG   %r28, TASK_PT_GR28(%r1)         /* return value 0 */ | 
|  | 177 | STREG   %r28, TASK_PT_ORIG_R28(%r1)     /* return value 0 (saved for signals) */ | 
|  | 178 | STREG	%r29, TASK_PT_GR29(%r1)		/* return value 1 */ | 
|  | 179 | STREG	%r31, TASK_PT_GR31(%r1)		/* preserve syscall return ptr */ | 
|  | 180 |  | 
|  | 181 | ldo	TASK_PT_FR0(%r1), %r27		/* save fpregs from the kernel */ | 
|  | 182 | save_fp	%r27				/* or potential task switch  */ | 
|  | 183 |  | 
|  | 184 | mfctl	%cr11, %r27			/* i.e. SAR */ | 
|  | 185 | STREG	%r27, TASK_PT_SAR(%r1) | 
|  | 186 |  | 
|  | 187 | loadgp | 
|  | 188 |  | 
|  | 189 | #ifdef __LP64__ | 
|  | 190 | ldo	-16(%r30),%r29			/* Reference param save area */ | 
|  | 191 | copy	%r19,%r2			/* W bit back to r2 */ | 
|  | 192 | #else | 
|  | 193 | /* no need to save these on stack in wide mode because the first 8 | 
|  | 194 | * args are passed in registers */ | 
|  | 195 | stw     %r22, -52(%r30)                 /* 5th argument */ | 
|  | 196 | stw     %r21, -56(%r30)                 /* 6th argument */ | 
|  | 197 | #endif | 
|  | 198 |  | 
|  | 199 | /* Are we being ptraced? */ | 
|  | 200 | mfctl	%cr30, %r1 | 
|  | 201 | LDREG	TI_TASK(%r1),%r1 | 
|  | 202 | LDREG	TASK_PTRACE(%r1), %r1 | 
|  | 203 | bb,<,n	%r1,31,.Ltracesys | 
|  | 204 |  | 
|  | 205 | /* Note!  We cannot use the syscall table that is mapped | 
|  | 206 | nearby since the gateway page is mapped execute-only. */ | 
|  | 207 |  | 
|  | 208 | #ifdef __LP64__ | 
|  | 209 | ldil	L%sys_call_table, %r1 | 
|  | 210 | or,=	%r2,%r2,%r2 | 
|  | 211 | addil	L%(sys_call_table64-sys_call_table), %r1 | 
|  | 212 | ldo	R%sys_call_table(%r1), %r19 | 
|  | 213 | or,=	%r2,%r2,%r2 | 
|  | 214 | ldo	R%sys_call_table64(%r1), %r19 | 
|  | 215 | #else | 
|  | 216 | ldil	L%sys_call_table, %r1 | 
|  | 217 | ldo     R%sys_call_table(%r1), %r19 | 
|  | 218 | #endif | 
|  | 219 | comiclr,>>=	__NR_Linux_syscalls, %r20, %r0 | 
|  | 220 | b,n	.Lsyscall_nosys | 
|  | 221 |  | 
|  | 222 | LDREGX  %r20(%r19), %r19 | 
|  | 223 |  | 
|  | 224 | /* If this is a sys_rt_sigreturn call, and the signal was received | 
|  | 225 | * when not in_syscall, then we want to return via syscall_exit_rfi, | 
|  | 226 | * not syscall_exit.  Signal no. in r20, in_syscall in r25 (see | 
|  | 227 | * trampoline code in signal.c). | 
|  | 228 | */ | 
|  | 229 | ldi	__NR_rt_sigreturn,%r2 | 
|  | 230 | comb,=	%r2,%r20,.Lrt_sigreturn | 
|  | 231 | .Lin_syscall: | 
|  | 232 | ldil	L%syscall_exit,%r2 | 
|  | 233 | be      0(%sr7,%r19) | 
|  | 234 | ldo	R%syscall_exit(%r2),%r2 | 
|  | 235 | .Lrt_sigreturn: | 
|  | 236 | comib,<> 0,%r25,.Lin_syscall | 
|  | 237 | ldil	L%syscall_exit_rfi,%r2 | 
|  | 238 | be      0(%sr7,%r19) | 
|  | 239 | ldo	R%syscall_exit_rfi(%r2),%r2 | 
|  | 240 |  | 
|  | 241 | /* Note!  Because we are not running where we were linked, any | 
|  | 242 | calls to functions external to this file must be indirect.  To | 
|  | 243 | be safe, we apply the opposite rule to functions within this | 
|  | 244 | file, with local labels given to them to ensure correctness. */ | 
|  | 245 |  | 
|  | 246 | .Lsyscall_nosys: | 
|  | 247 | syscall_nosys: | 
|  | 248 | ldil	L%syscall_exit,%r1 | 
|  | 249 | be	R%syscall_exit(%sr7,%r1) | 
|  | 250 | ldo	-ENOSYS(%r0),%r28		   /* set errno */ | 
|  | 251 |  | 
|  | 252 |  | 
|  | 253 | /* Warning! This trace code is a virtual duplicate of the code above so be | 
|  | 254 | * sure to maintain both! */ | 
|  | 255 | .Ltracesys: | 
|  | 256 | tracesys: | 
|  | 257 | /* Need to save more registers so the debugger can see where we | 
|  | 258 | * are.  This saves only the lower 8 bits of PSW, so that the C | 
|  | 259 | * bit is still clear on syscalls, and the D bit is set if this | 
|  | 260 | * full register save path has been executed.  We check the D | 
|  | 261 | * bit on syscall_return_rfi to determine which registers to | 
|  | 262 | * restore.  An interrupt results in a full PSW saved with the | 
|  | 263 | * C bit set, a non-straced syscall entry results in C and D clear | 
|  | 264 | * in the saved PSW. | 
|  | 265 | */ | 
|  | 266 | ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */ | 
|  | 267 | LDREG	TI_TASK(%r1), %r1 | 
|  | 268 | ssm	0,%r2 | 
|  | 269 | STREG	%r2,TASK_PT_PSW(%r1)		/* Lower 8 bits only!! */ | 
|  | 270 | mfsp	%sr0,%r2 | 
|  | 271 | STREG	%r2,TASK_PT_SR0(%r1) | 
|  | 272 | mfsp	%sr1,%r2 | 
|  | 273 | STREG	%r2,TASK_PT_SR1(%r1) | 
|  | 274 | mfsp	%sr2,%r2 | 
|  | 275 | STREG	%r2,TASK_PT_SR2(%r1) | 
|  | 276 | mfsp	%sr3,%r2 | 
|  | 277 | STREG	%r2,TASK_PT_SR3(%r1) | 
|  | 278 | STREG	%r2,TASK_PT_SR4(%r1) | 
|  | 279 | STREG	%r2,TASK_PT_SR5(%r1) | 
|  | 280 | STREG	%r2,TASK_PT_SR6(%r1) | 
|  | 281 | STREG	%r2,TASK_PT_SR7(%r1) | 
|  | 282 | STREG	%r2,TASK_PT_IASQ0(%r1) | 
|  | 283 | STREG	%r2,TASK_PT_IASQ1(%r1) | 
|  | 284 | LDREG	TASK_PT_GR31(%r1),%r2 | 
|  | 285 | STREG	%r2,TASK_PT_IAOQ0(%r1) | 
|  | 286 | ldo	4(%r2),%r2 | 
|  | 287 | STREG	%r2,TASK_PT_IAOQ1(%r1) | 
|  | 288 | ldo	TASK_REGS(%r1),%r2 | 
|  | 289 | /* reg_save %r2 */ | 
|  | 290 | STREG	%r3,PT_GR3(%r2) | 
|  | 291 | STREG	%r4,PT_GR4(%r2) | 
|  | 292 | STREG	%r5,PT_GR5(%r2) | 
|  | 293 | STREG	%r6,PT_GR6(%r2) | 
|  | 294 | STREG	%r7,PT_GR7(%r2) | 
|  | 295 | STREG	%r8,PT_GR8(%r2) | 
|  | 296 | STREG	%r9,PT_GR9(%r2) | 
|  | 297 | STREG	%r10,PT_GR10(%r2) | 
|  | 298 | STREG	%r11,PT_GR11(%r2) | 
|  | 299 | STREG	%r12,PT_GR12(%r2) | 
|  | 300 | STREG	%r13,PT_GR13(%r2) | 
|  | 301 | STREG	%r14,PT_GR14(%r2) | 
|  | 302 | STREG	%r15,PT_GR15(%r2) | 
|  | 303 | STREG	%r16,PT_GR16(%r2) | 
|  | 304 | STREG	%r17,PT_GR17(%r2) | 
|  | 305 | STREG	%r18,PT_GR18(%r2) | 
|  | 306 | /* Finished saving things for the debugger */ | 
|  | 307 |  | 
|  | 308 | ldil	L%syscall_trace,%r1 | 
|  | 309 | ldil	L%tracesys_next,%r2 | 
|  | 310 | be	R%syscall_trace(%sr7,%r1) | 
|  | 311 | ldo	R%tracesys_next(%r2),%r2 | 
|  | 312 |  | 
|  | 313 | tracesys_next: | 
|  | 314 | ldil	L%sys_call_table,%r1 | 
|  | 315 | ldo     R%sys_call_table(%r1), %r19 | 
|  | 316 |  | 
|  | 317 | ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */ | 
|  | 318 | LDREG	TI_TASK(%r1), %r1 | 
|  | 319 | LDREG   TASK_PT_GR20(%r1), %r20 | 
|  | 320 | LDREG   TASK_PT_GR26(%r1), %r26		/* Restore the users args */ | 
|  | 321 | LDREG   TASK_PT_GR25(%r1), %r25 | 
|  | 322 | LDREG   TASK_PT_GR24(%r1), %r24 | 
|  | 323 | LDREG   TASK_PT_GR23(%r1), %r23 | 
|  | 324 | #ifdef __LP64__ | 
|  | 325 | LDREG   TASK_PT_GR22(%r1), %r22 | 
|  | 326 | LDREG   TASK_PT_GR21(%r1), %r21 | 
|  | 327 | ldo	-16(%r30),%r29			/* Reference param save area */ | 
|  | 328 | #endif | 
|  | 329 |  | 
|  | 330 | comiclr,>>=	__NR_Linux_syscalls, %r20, %r0 | 
|  | 331 | b,n	.Lsyscall_nosys | 
|  | 332 |  | 
|  | 333 | LDREGX  %r20(%r19), %r19 | 
|  | 334 |  | 
|  | 335 | /* If this is a sys_rt_sigreturn call, and the signal was received | 
|  | 336 | * when not in_syscall, then we want to return via syscall_exit_rfi, | 
|  | 337 | * not syscall_exit.  Signal no. in r20, in_syscall in r25 (see | 
|  | 338 | * trampoline code in signal.c). | 
|  | 339 | */ | 
|  | 340 | ldi	__NR_rt_sigreturn,%r2 | 
|  | 341 | comb,=	%r2,%r20,.Ltrace_rt_sigreturn | 
|  | 342 | .Ltrace_in_syscall: | 
|  | 343 | ldil	L%tracesys_exit,%r2 | 
|  | 344 | be      0(%sr7,%r19) | 
|  | 345 | ldo	R%tracesys_exit(%r2),%r2 | 
|  | 346 |  | 
|  | 347 | /* Do *not* call this function on the gateway page, because it | 
|  | 348 | makes a direct call to syscall_trace. */ | 
|  | 349 |  | 
|  | 350 | tracesys_exit: | 
|  | 351 | ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */ | 
|  | 352 | LDREG	TI_TASK(%r1), %r1 | 
|  | 353 | #ifdef __LP64__ | 
|  | 354 | ldo	-16(%r30),%r29			/* Reference param save area */ | 
|  | 355 | #endif | 
|  | 356 | bl	syscall_trace, %r2 | 
|  | 357 | STREG   %r28,TASK_PT_GR28(%r1)          /* save return value now */ | 
|  | 358 | ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */ | 
|  | 359 | LDREG	TI_TASK(%r1), %r1 | 
|  | 360 | LDREG   TASK_PT_GR28(%r1), %r28		/* Restore return val. */ | 
|  | 361 |  | 
|  | 362 | ldil	L%syscall_exit,%r1 | 
|  | 363 | be,n	R%syscall_exit(%sr7,%r1) | 
|  | 364 |  | 
|  | 365 | .Ltrace_rt_sigreturn: | 
|  | 366 | comib,<> 0,%r25,.Ltrace_in_syscall | 
|  | 367 | ldil	L%tracesys_sigexit,%r2 | 
|  | 368 | be      0(%sr7,%r19) | 
|  | 369 | ldo	R%tracesys_sigexit(%r2),%r2 | 
|  | 370 |  | 
|  | 371 | tracesys_sigexit: | 
|  | 372 | ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */ | 
|  | 373 | LDREG	0(%r1), %r1 | 
|  | 374 | #ifdef __LP64__ | 
|  | 375 | ldo	-16(%r30),%r29			/* Reference param save area */ | 
|  | 376 | #endif | 
|  | 377 | bl	syscall_trace, %r2 | 
|  | 378 | nop | 
|  | 379 |  | 
|  | 380 | ldil	L%syscall_exit_rfi,%r1 | 
|  | 381 | be,n	R%syscall_exit_rfi(%sr7,%r1) | 
|  | 382 |  | 
|  | 383 |  | 
|  | 384 | /********************************************************* | 
|  | 385 | Light-weight-syscall code | 
|  | 386 |  | 
|  | 387 | r20 - lws number | 
|  | 388 | r26,r25,r24,r23,r22 - Input registers | 
|  | 389 | r28 - Function return register | 
|  | 390 | r21 - Error code. | 
|  | 391 |  | 
|  | 392 | Scracth: Any of the above that aren't being | 
|  | 393 | currently used, including r1. | 
|  | 394 |  | 
|  | 395 | Return pointer: r31 (Not usable) | 
|  | 396 |  | 
|  | 397 | Error codes returned by entry path: | 
|  | 398 |  | 
|  | 399 | ENOSYS - r20 was an invalid LWS number. | 
|  | 400 |  | 
|  | 401 | *********************************************************/ | 
|  | 402 | lws_start: | 
|  | 403 | /* Gate and ensure we return to userspace */ | 
|  | 404 | gate	.+8, %r0 | 
|  | 405 | depi	3, 31, 2, %r31	/* Ensure we return to userspace */ | 
|  | 406 |  | 
|  | 407 | #ifdef __LP64__ | 
|  | 408 | /* FIXME: If we are a 64-bit kernel just | 
|  | 409 | *        turn this on unconditionally. | 
|  | 410 | */ | 
|  | 411 | ssm	PSW_SM_W, %r1 | 
|  | 412 | extrd,u	%r1,PSW_W_BIT,1,%r1 | 
|  | 413 | /* sp must be aligned on 4, so deposit the W bit setting into | 
|  | 414 | * the bottom of sp temporarily */ | 
|  | 415 | or,ev	%r1,%r30,%r30 | 
|  | 416 |  | 
|  | 417 | /* Clip LWS number to a 32-bit value always */ | 
|  | 418 | depdi	0, 31, 32, %r20 | 
|  | 419 | #endif | 
|  | 420 |  | 
|  | 421 | /* Is the lws entry number valid? */ | 
|  | 422 | comiclr,>>=	__NR_lws_entries, %r20, %r0 | 
|  | 423 | b,n	lws_exit_nosys | 
|  | 424 |  | 
|  | 425 | /* WARNING: Trashing sr2 and sr3 */ | 
|  | 426 | mfsp	%sr7,%r1			/* get userspace into sr3 */ | 
|  | 427 | mtsp	%r1,%sr3 | 
|  | 428 | mtsp	%r0,%sr2			/* get kernel space into sr2 */ | 
|  | 429 |  | 
|  | 430 | /* Load table start */ | 
|  | 431 | ldil	L%lws_table, %r1 | 
|  | 432 | ldo	R%lws_table(%r1), %r28	/* Scratch use of r28 */ | 
|  | 433 | LDREGX	%r20(%sr2,r28), %r21	/* Scratch use of r21 */ | 
|  | 434 |  | 
|  | 435 | /* Jump to lws, lws table pointers already relocated */ | 
|  | 436 | be,n	0(%sr2,%r21) | 
|  | 437 |  | 
|  | 438 | lws_exit_nosys: | 
|  | 439 | ldo	-ENOSYS(%r0),%r21		   /* set errno */ | 
|  | 440 | /* Fall through: Return to userspace */ | 
|  | 441 |  | 
|  | 442 | lws_exit: | 
|  | 443 | #ifdef __LP64__ | 
|  | 444 | /* decide whether to reset the wide mode bit | 
|  | 445 | * | 
|  | 446 | * For a syscall, the W bit is stored in the lowest bit | 
|  | 447 | * of sp.  Extract it and reset W if it is zero */ | 
|  | 448 | extrd,u,*<>	%r30,63,1,%r1 | 
|  | 449 | rsm	PSW_SM_W, %r0 | 
|  | 450 | /* now reset the lowest bit of sp if it was set */ | 
|  | 451 | xor	%r30,%r1,%r30 | 
|  | 452 | #endif | 
|  | 453 | be,n	0(%sr3, %r31) | 
|  | 454 |  | 
|  | 455 |  | 
|  | 456 |  | 
|  | 457 | /*************************************************** | 
|  | 458 | Implementing CAS as an atomic operation: | 
|  | 459 |  | 
|  | 460 | %r26 - Address to examine | 
|  | 461 | %r25 - Old value to check (old) | 
|  | 462 | %r24 - New value to set (new) | 
|  | 463 | %r28 - Return prev through this register. | 
|  | 464 | %r21 - Kernel error code | 
|  | 465 |  | 
|  | 466 | If debugging is DISabled: | 
|  | 467 |  | 
|  | 468 | %r21 has the following meanings: | 
|  | 469 |  | 
|  | 470 | EAGAIN - CAS is busy, ldcw failed, try again. | 
|  | 471 | EFAULT - Read or write failed. | 
|  | 472 |  | 
|  | 473 | If debugging is enabled: | 
|  | 474 |  | 
|  | 475 | EDEADLOCK - CAS called recursively. | 
|  | 476 | EAGAIN && r28 == 1 - CAS is busy. Lock contended. | 
|  | 477 | EAGAIN && r28 == 2 - CAS is busy. ldcw failed. | 
|  | 478 | EFAULT - Read or write failed. | 
|  | 479 |  | 
|  | 480 | Scratch: r20, r28, r1 | 
|  | 481 |  | 
|  | 482 | ****************************************************/ | 
|  | 483 |  | 
|  | 484 | /* Do not enable LWS debugging */ | 
|  | 485 | #define ENABLE_LWS_DEBUG 0 | 
|  | 486 |  | 
|  | 487 | /* ELF64 Process entry path */ | 
|  | 488 | lws_compare_and_swap64: | 
|  | 489 | #ifdef __LP64__ | 
|  | 490 | b,n	lws_compare_and_swap | 
|  | 491 | #else | 
|  | 492 | /* If we are not a 64-bit kernel, then we don't | 
|  | 493 | * implement having 64-bit input registers | 
|  | 494 | */ | 
|  | 495 | b,n	lws_exit_nosys | 
|  | 496 | #endif | 
|  | 497 |  | 
|  | 498 | /* ELF32 Process entry path */ | 
|  | 499 | lws_compare_and_swap32: | 
|  | 500 | #ifdef __LP64__ | 
|  | 501 | /* Clip all the input registers */ | 
|  | 502 | depdi	0, 31, 32, %r26 | 
|  | 503 | depdi	0, 31, 32, %r25 | 
|  | 504 | depdi	0, 31, 32, %r24 | 
|  | 505 | #endif | 
|  | 506 |  | 
|  | 507 | lws_compare_and_swap: | 
|  | 508 | #ifdef CONFIG_SMP | 
|  | 509 | /* Load start of lock table */ | 
|  | 510 | ldil	L%lws_lock_start, %r20 | 
|  | 511 | ldo	R%lws_lock_start(%r20), %r28 | 
|  | 512 |  | 
|  | 513 | /* Extract four bits from r26 and hash lock (Bits 4-7) */ | 
|  | 514 | extru  %r26, 27, 4, %r20 | 
|  | 515 |  | 
|  | 516 | /* Find lock to use, the hash is either one of 0 to | 
|  | 517 | 15, multiplied by 16 (keep it 16-byte aligned) | 
|  | 518 | and add to the lock table offset. */ | 
|  | 519 | shlw	%r20, 4, %r20 | 
|  | 520 | add	%r20, %r28, %r20 | 
|  | 521 |  | 
|  | 522 | # ifdef ENABLE_LWS_DEBUG | 
|  | 523 | /* | 
|  | 524 | DEBUG, check for deadlock! | 
|  | 525 | If the thread register values are the same | 
|  | 526 | then we were the one that locked it last and | 
|  | 527 | this is a recurisve call that will deadlock. | 
|  | 528 | We *must* giveup this call and fail. | 
|  | 529 | */ | 
|  | 530 | ldw	4(%sr2,%r20), %r28			/* Load thread register */ | 
|  | 531 | mfctl	%cr27, %r21				/* Get current thread register */ | 
|  | 532 | cmpb,<>,n	%r21, %r28, cas_lock		/* Called recursive? */ | 
|  | 533 | b	lws_exit				/* Return error! */ | 
|  | 534 | ldo	-EDEADLOCK(%r0), %r21 | 
|  | 535 | cas_lock: | 
|  | 536 | cmpb,=,n	%r0, %r28, cas_nocontend	/* Is nobody using it? */ | 
|  | 537 | ldo	1(%r0), %r28				/* 1st case */ | 
|  | 538 | b	lws_exit				/* Contended... */ | 
|  | 539 | ldo	-EAGAIN(%r0), %r21			/* Spin in userspace */ | 
|  | 540 | cas_nocontend: | 
|  | 541 | # endif | 
|  | 542 | /* ENABLE_LWS_DEBUG */ | 
|  | 543 |  | 
|  | 544 | ldcw	0(%sr2,%r20), %r28			/* Try to acquire the lock */ | 
|  | 545 | cmpb,<>,n	%r0, %r28, cas_action		/* Did we get it? */ | 
|  | 546 | cas_wouldblock: | 
|  | 547 | ldo	2(%r0), %r28				/* 2nd case */ | 
|  | 548 | b	lws_exit				/* Contended... */ | 
|  | 549 | ldo	-EAGAIN(%r0), %r21			/* Spin in userspace */ | 
|  | 550 | #endif | 
|  | 551 | /* CONFIG_SMP */ | 
|  | 552 |  | 
|  | 553 | /* | 
|  | 554 | prev = *addr; | 
|  | 555 | if ( prev == old ) | 
|  | 556 | *addr = new; | 
|  | 557 | return prev; | 
|  | 558 | */ | 
|  | 559 |  | 
|  | 560 | /* NOTES: | 
|  | 561 | This all works becuse intr_do_signal | 
|  | 562 | and schedule both check the return iasq | 
|  | 563 | and see that we are on the kernel page | 
|  | 564 | so this process is never scheduled off | 
|  | 565 | or is ever sent any signal of any sort, | 
|  | 566 | thus it is wholly atomic from usrspaces | 
|  | 567 | perspective | 
|  | 568 | */ | 
|  | 569 | cas_action: | 
|  | 570 | #if defined CONFIG_SMP && defined ENABLE_LWS_DEBUG | 
|  | 571 | /* DEBUG */ | 
|  | 572 | mfctl	%cr27, %r1 | 
|  | 573 | stw	%r1, 4(%sr2,%r20) | 
|  | 574 | #endif | 
|  | 575 | /* The load and store could fail */ | 
|  | 576 | 1:	ldw	0(%sr3,%r26), %r28 | 
|  | 577 | sub,<>	%r28, %r25, %r0 | 
|  | 578 | 2:	stw	%r24, 0(%sr3,%r26) | 
|  | 579 | #ifdef CONFIG_SMP | 
|  | 580 | /* Free lock */ | 
|  | 581 | stw	%r20, 0(%sr2,%r20) | 
|  | 582 | # ifdef ENABLE_LWS_DEBUG | 
|  | 583 | /* Clear thread register indicator */ | 
|  | 584 | stw	%r0, 4(%sr2,%r20) | 
|  | 585 | # endif | 
|  | 586 | #endif | 
|  | 587 | /* Return to userspace, set no error */ | 
|  | 588 | b	lws_exit | 
|  | 589 | copy	%r0, %r21 | 
|  | 590 |  | 
|  | 591 | 3: | 
|  | 592 | /* Error occured on load or store */ | 
|  | 593 | #ifdef CONFIG_SMP | 
|  | 594 | /* Free lock */ | 
|  | 595 | stw	%r20, 0(%sr2,%r20) | 
|  | 596 | # ifdef ENABLE_LWS_DEBUG | 
|  | 597 | stw	%r0, 4(%sr2,%r20) | 
|  | 598 | # endif | 
|  | 599 | #endif | 
|  | 600 | b	lws_exit | 
|  | 601 | ldo	-EFAULT(%r0),%r21	/* set errno */ | 
|  | 602 | nop | 
|  | 603 | nop | 
|  | 604 | nop | 
|  | 605 | nop | 
|  | 606 |  | 
|  | 607 | /* Two exception table entries, one for the load, | 
|  | 608 | the other for the store. Either return -EFAULT. | 
|  | 609 | Each of the entries must be relocated. */ | 
|  | 610 | .section __ex_table,"aw" | 
|  | 611 | #ifdef __LP64__ | 
|  | 612 | /* Pad the address calculation */ | 
|  | 613 | .word	0,(2b - linux_gateway_page) | 
|  | 614 | .word	0,(3b - linux_gateway_page) | 
|  | 615 | #else | 
|  | 616 | .word	(2b - linux_gateway_page) | 
|  | 617 | .word	(3b - linux_gateway_page) | 
|  | 618 | #endif | 
|  | 619 | .previous | 
|  | 620 |  | 
|  | 621 | .section __ex_table,"aw" | 
|  | 622 | #ifdef __LP64__ | 
|  | 623 | /* Pad the address calculation */ | 
|  | 624 | .word	0,(1b - linux_gateway_page) | 
|  | 625 | .word	0,(3b - linux_gateway_page) | 
|  | 626 | #else | 
|  | 627 | .word	(1b - linux_gateway_page) | 
|  | 628 | .word	(3b - linux_gateway_page) | 
|  | 629 | #endif | 
|  | 630 | .previous | 
|  | 631 |  | 
|  | 632 | end_compare_and_swap: | 
|  | 633 |  | 
|  | 634 | /* Make sure nothing else is placed on this page */ | 
|  | 635 | .align 4096 | 
|  | 636 | .export end_linux_gateway_page | 
|  | 637 | end_linux_gateway_page: | 
|  | 638 |  | 
|  | 639 | /* Relocate symbols assuming linux_gateway_page is mapped | 
|  | 640 | to virtual address 0x0 */ | 
|  | 641 | #ifdef __LP64__ | 
|  | 642 | /* FIXME: The code will always be on the gateay page | 
|  | 643 | and thus it will be on the first 4k, the | 
|  | 644 | assembler seems to think that the final | 
|  | 645 | subtraction result is only a word in | 
|  | 646 | length, so we pad the value. | 
|  | 647 | */ | 
|  | 648 | #define LWS_ENTRY(_name_) .word 0,(lws_##_name_ - linux_gateway_page) | 
|  | 649 | #else | 
|  | 650 | #define LWS_ENTRY(_name_) .word  (lws_##_name_ - linux_gateway_page) | 
|  | 651 | #endif | 
|  | 652 |  | 
|  | 653 | .align 4096 | 
|  | 654 | /* Light-weight-syscall table */ | 
|  | 655 | /* Start of lws table. */ | 
|  | 656 | .export lws_table | 
|  | 657 | .Llws_table: | 
|  | 658 | lws_table: | 
|  | 659 | LWS_ENTRY(compare_and_swap32)	/* 0 - ELF32 Atomic compare and swap */ | 
|  | 660 | LWS_ENTRY(compare_and_swap64)	/* 1 - ELF64 Atomic compare and swap */ | 
|  | 661 | /* End of lws table */ | 
|  | 662 |  | 
|  | 663 | .align 4096 | 
|  | 664 | .export sys_call_table | 
|  | 665 | .Lsys_call_table: | 
|  | 666 | sys_call_table: | 
|  | 667 | #include "syscall_table.S" | 
|  | 668 |  | 
|  | 669 | #ifdef __LP64__ | 
|  | 670 | .align 4096 | 
|  | 671 | .export sys_call_table64 | 
|  | 672 | .Lsys_call_table64: | 
|  | 673 | sys_call_table64: | 
|  | 674 | #define SYSCALL_TABLE_64BIT | 
|  | 675 | #include "syscall_table.S" | 
|  | 676 | #endif | 
|  | 677 |  | 
|  | 678 | #ifdef CONFIG_SMP | 
|  | 679 | /* | 
|  | 680 | All light-weight-syscall atomic operations | 
|  | 681 | will use this set of locks | 
|  | 682 | */ | 
|  | 683 | .section .data | 
|  | 684 | .align 4096 | 
|  | 685 | .export lws_lock_start | 
|  | 686 | .Llws_lock_start: | 
|  | 687 | lws_lock_start: | 
|  | 688 | /* lws locks */ | 
|  | 689 | .align 16 | 
|  | 690 | .rept 16 | 
|  | 691 | /* Keep locks aligned at 16-bytes */ | 
|  | 692 | .word 1 | 
|  | 693 | .word 0 | 
|  | 694 | .word 0 | 
|  | 695 | .word 0 | 
|  | 696 | .endr | 
|  | 697 | .previous | 
|  | 698 | #endif | 
|  | 699 | /* CONFIG_SMP for lws_lock_start */ | 
|  | 700 |  | 
|  | 701 | .end | 
|  | 702 |  | 
|  | 703 |  |