| 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 |  |