| blob | 245d3e1ec7e1b00dc97f125f4ef0cc90e45b0aa8 |
1 /*
2 * This file contains the code that gets mapped at the upper end of each task's text
3 * region. For now, it contains the signal trampoline code only.
4 *
5 * Copyright (C) 1999-2003 Hewlett-Packard Co
6 * David Mosberger-Tang <davidm@hpl.hp.com>
7 */
10 #include <asm/asmmacro.h>
11 #include <asm/errno.h>
12 #include <asm/asm-offsets.h>
13 #include <asm/sigcontext.h>
14 #include <asm/system.h>
15 #include <asm/unistd.h>
16 #include "paravirt_inst.h"
18 /*
19 * We can't easily refer to symbols inside the kernel. To avoid full runtime relocation,
20 * complications with the linker (which likes to create PLT stubs for branches
21 * to targets outside the shared object) and to avoid multi-phase kernel builds, we
22 * simply create minimalistic "patch lists" in special ELF sections.
23 */
24 .section ".data..patch.fsyscall_table", "a"
25 .previous
26 #define LOAD_FSYSCALL_TABLE(reg) \
27 [1:] movl reg=0; \
28 .xdata4 ".data..patch.fsyscall_table", 1b-.
30 .section ".data..patch.brl_fsys_bubble_down", "a"
31 .previous
32 #define BRL_COND_FSYS_BUBBLE_DOWN(pr) \
33 [1:](pr)brl.cond.sptk 0; \
34 ;; \
35 .xdata4 ".data..patch.brl_fsys_bubble_down", 1b-.
37 GLOBAL_ENTRY(__kernel_syscall_via_break)
38 .prologue
39 .altrp b6
40 .body
41 /*
42 * Note: for (fast) syscall restart to work, the break instruction must be
43 * the first one in the bundle addressed by syscall_via_break.
44 */
45 { .mib
46 break 0x100000
47 nop.i 0
48 br.ret.sptk.many b6
49 }
50 END(__kernel_syscall_via_break)
52 # define ARG0_OFF (16 + IA64_SIGFRAME_ARG0_OFFSET)
53 # define ARG1_OFF (16 + IA64_SIGFRAME_ARG1_OFFSET)
54 # define ARG2_OFF (16 + IA64_SIGFRAME_ARG2_OFFSET)
55 # define SIGHANDLER_OFF (16 + IA64_SIGFRAME_HANDLER_OFFSET)
56 # define SIGCONTEXT_OFF (16 + IA64_SIGFRAME_SIGCONTEXT_OFFSET)
58 # define FLAGS_OFF IA64_SIGCONTEXT_FLAGS_OFFSET
59 # define CFM_OFF IA64_SIGCONTEXT_CFM_OFFSET
60 # define FR6_OFF IA64_SIGCONTEXT_FR6_OFFSET
61 # define BSP_OFF IA64_SIGCONTEXT_AR_BSP_OFFSET
62 # define RNAT_OFF IA64_SIGCONTEXT_AR_RNAT_OFFSET
63 # define UNAT_OFF IA64_SIGCONTEXT_AR_UNAT_OFFSET
64 # define FPSR_OFF IA64_SIGCONTEXT_AR_FPSR_OFFSET
65 # define PR_OFF IA64_SIGCONTEXT_PR_OFFSET
66 # define RP_OFF IA64_SIGCONTEXT_IP_OFFSET
67 # define SP_OFF IA64_SIGCONTEXT_R12_OFFSET
68 # define RBS_BASE_OFF IA64_SIGCONTEXT_RBS_BASE_OFFSET
69 # define LOADRS_OFF IA64_SIGCONTEXT_LOADRS_OFFSET
70 # define base0 r2
71 # define base1 r3
72 /*
73 * When we get here, the memory stack looks like this:
74 *
75 * +===============================+
76 * | |
77 * // struct sigframe //
78 * | |
79 * +-------------------------------+ <-- sp+16
80 * | 16 byte of scratch |
81 * | space |
82 * +-------------------------------+ <-- sp
83 *
84 * The register stack looks _exactly_ the way it looked at the time the signal
85 * occurred. In other words, we're treading on a potential mine-field: each
86 * incoming general register may be a NaT value (including sp, in which case the
87 * process ends up dying with a SIGSEGV).
88 *
89 * The first thing need to do is a cover to get the registers onto the backing
90 * store. Once that is done, we invoke the signal handler which may modify some
91 * of the machine state. After returning from the signal handler, we return
92 * control to the previous context by executing a sigreturn system call. A signal
93 * handler may call the rt_sigreturn() function to directly return to a given
94 * sigcontext. However, the user-level sigreturn() needs to do much more than
95 * calling the rt_sigreturn() system call as it needs to unwind the stack to
96 * restore preserved registers that may have been saved on the signal handler's
97 * call stack.
98 */
100 #define SIGTRAMP_SAVES \
101 .unwabi 3, 's'; /* mark this as a sigtramp handler (saves scratch regs) */ \
102 .unwabi @svr4, 's'; /* backwards compatibility with old unwinders (remove in v2.7) */ \
103 .savesp ar.unat, UNAT_OFF+SIGCONTEXT_OFF; \
104 .savesp ar.fpsr, FPSR_OFF+SIGCONTEXT_OFF; \
105 .savesp pr, PR_OFF+SIGCONTEXT_OFF; \
106 .savesp rp, RP_OFF+SIGCONTEXT_OFF; \
107 .savesp ar.pfs, CFM_OFF+SIGCONTEXT_OFF; \
108 .vframesp SP_OFF+SIGCONTEXT_OFF
110 GLOBAL_ENTRY(__kernel_sigtramp)
111 // describe the state that is active when we get here:
112 .prologue
113 SIGTRAMP_SAVES
114 .body
116 .label_state 1
118 adds base0=SIGHANDLER_OFF,sp
119 adds base1=RBS_BASE_OFF+SIGCONTEXT_OFF,sp
120 br.call.sptk.many rp=1f
121 1:
122 ld8 r17=[base0],(ARG0_OFF-SIGHANDLER_OFF) // get pointer to signal handler's plabel
123 ld8 r15=[base1] // get address of new RBS base (or NULL)
124 cover // push args in interrupted frame onto backing store
125 ;;
126 cmp.ne p1,p0=r15,r0 // do we need to switch rbs? (note: pr is saved by kernel)
127 mov.m r9=ar.bsp // fetch ar.bsp
128 .spillsp.p p1, ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
129 (p1) br.cond.spnt setup_rbs // yup -> (clobbers p8, r14-r16, and r18-r20)
130 back_from_setup_rbs:
131 alloc r8=ar.pfs,0,0,3,0
132 ld8 out0=[base0],16 // load arg0 (signum)
133 adds base1=(ARG1_OFF-(RBS_BASE_OFF+SIGCONTEXT_OFF)),base1
134 ;;
135 ld8 out1=[base1] // load arg1 (siginfop)
136 ld8 r10=[r17],8 // get signal handler entry point
137 ;;
138 ld8 out2=[base0] // load arg2 (sigcontextp)
139 ld8 gp=[r17] // get signal handler's global pointer
140 adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp
141 ;;
142 .spillsp ar.bsp, BSP_OFF+SIGCONTEXT_OFF
143 st8 [base0]=r9 // save sc_ar_bsp
144 adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp
145 adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp
146 ;;
147 stf.spill [base0]=f6,32
148 stf.spill [base1]=f7,32
149 ;;
150 stf.spill [base0]=f8,32
151 stf.spill [base1]=f9,32
152 mov b6=r10
153 ;;
154 stf.spill [base0]=f10,32
155 stf.spill [base1]=f11,32
156 ;;
157 stf.spill [base0]=f12,32
158 stf.spill [base1]=f13,32
159 ;;
160 stf.spill [base0]=f14,32
161 stf.spill [base1]=f15,32
162 br.call.sptk.many rp=b6 // call the signal handler
163 .ret0: adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp
164 ;;
165 ld8 r15=[base0] // fetch sc_ar_bsp
166 mov r14=ar.bsp
167 ;;
168 cmp.ne p1,p0=r14,r15 // do we need to restore the rbs?
169 (p1) br.cond.spnt restore_rbs // yup -> (clobbers r14-r18, f6 & f7)
170 ;;
171 back_from_restore_rbs:
172 adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp
173 adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp
174 ;;
175 ldf.fill f6=[base0],32
176 ldf.fill f7=[base1],32
177 ;;
178 ldf.fill f8=[base0],32
179 ldf.fill f9=[base1],32
180 ;;
181 ldf.fill f10=[base0],32
182 ldf.fill f11=[base1],32
183 ;;
184 ldf.fill f12=[base0],32
185 ldf.fill f13=[base1],32
186 ;;
187 ldf.fill f14=[base0],32
188 ldf.fill f15=[base1],32
189 mov r15=__NR_rt_sigreturn
190 .restore sp // pop .prologue
191 break __BREAK_SYSCALL
193 .prologue
194 SIGTRAMP_SAVES
195 setup_rbs:
196 mov ar.rsc=0 // put RSE into enforced lazy mode
197 ;;
198 .save ar.rnat, r19
199 mov r19=ar.rnat // save RNaT before switching backing store area
200 adds r14=(RNAT_OFF+SIGCONTEXT_OFF),sp
202 mov r18=ar.bspstore
203 mov ar.bspstore=r15 // switch over to new register backing store area
204 ;;
206 .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
207 st8 [r14]=r19 // save sc_ar_rnat
208 .body
209 mov.m r16=ar.bsp // sc_loadrs <- (new bsp - new bspstore) << 16
210 adds r14=(LOADRS_OFF+SIGCONTEXT_OFF),sp
211 ;;
212 invala
213 sub r15=r16,r15
214 extr.u r20=r18,3,6
215 ;;
216 mov ar.rsc=0xf // set RSE into eager mode, pl 3
217 cmp.eq p8,p0=63,r20
218 shl r15=r15,16
219 ;;
220 st8 [r14]=r15 // save sc_loadrs
221 (p8) st8 [r18]=r19 // if bspstore points at RNaT slot, store RNaT there now
222 .restore sp // pop .prologue
223 br.cond.sptk back_from_setup_rbs
225 .prologue
226 SIGTRAMP_SAVES
227 .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
228 .body
229 restore_rbs:
230 // On input:
231 // r14 = bsp1 (bsp at the time of return from signal handler)
232 // r15 = bsp0 (bsp at the time the signal occurred)
233 //
234 // Here, we need to calculate bspstore0, the value that ar.bspstore needs
235 // to be set to, based on bsp0 and the size of the dirty partition on
236 // the alternate stack (sc_loadrs >> 16). This can be done with the
237 // following algorithm:
238 //
239 // bspstore0 = rse_skip_regs(bsp0, -rse_num_regs(bsp1 - (loadrs >> 19), bsp1));
240 //
241 // This is what the code below does.
242 //
243 alloc r2=ar.pfs,0,0,0,0 // alloc null frame
244 adds r16=(LOADRS_OFF+SIGCONTEXT_OFF),sp
245 adds r18=(RNAT_OFF+SIGCONTEXT_OFF),sp
246 ;;
247 ld8 r17=[r16]
248 ld8 r16=[r18] // get new rnat
249 extr.u r18=r15,3,6 // r18 <- rse_slot_num(bsp0)
250 ;;
251 mov ar.rsc=r17 // put RSE into enforced lazy mode
252 shr.u r17=r17,16
253 ;;
254 sub r14=r14,r17 // r14 (bspstore1) <- bsp1 - (sc_loadrs >> 16)
255 shr.u r17=r17,3 // r17 <- (sc_loadrs >> 19)
256 ;;
257 loadrs // restore dirty partition
258 extr.u r14=r14,3,6 // r14 <- rse_slot_num(bspstore1)
259 ;;
260 add r14=r14,r17 // r14 <- rse_slot_num(bspstore1) + (sc_loadrs >> 19)
261 ;;
262 shr.u r14=r14,6 // r14 <- (rse_slot_num(bspstore1) + (sc_loadrs >> 19))/0x40
263 ;;
264 sub r14=r14,r17 // r14 <- -rse_num_regs(bspstore1, bsp1)
265 movl r17=0x8208208208208209
266 ;;
267 add r18=r18,r14 // r18 (delta) <- rse_slot_num(bsp0) - rse_num_regs(bspstore1,bsp1)
268 setf.sig f7=r17
269 cmp.lt p7,p0=r14,r0 // p7 <- (r14 < 0)?
270 ;;
271 (p7) adds r18=-62,r18 // delta -= 62
272 ;;
273 setf.sig f6=r18
274 ;;
275 xmpy.h f6=f6,f7
276 ;;
277 getf.sig r17=f6
278 ;;
279 add r17=r17,r18
280 shr r18=r18,63
281 ;;
282 shr r17=r17,5
283 ;;
284 sub r17=r17,r18 // r17 = delta/63
285 ;;
286 add r17=r14,r17 // r17 <- delta/63 - rse_num_regs(bspstore1, bsp1)
287 ;;
288 shladd r15=r17,3,r15 // r15 <- bsp0 + 8*(delta/63 - rse_num_regs(bspstore1, bsp1))
289 ;;
290 mov ar.bspstore=r15 // switch back to old register backing store area
291 ;;
292 mov ar.rnat=r16 // restore RNaT
293 mov ar.rsc=0xf // (will be restored later on from sc_ar_rsc)
294 // invala not necessary as that will happen when returning to user-mode
295 br.cond.sptk back_from_restore_rbs
296 END(__kernel_sigtramp)
298 /*
299 * On entry:
300 * r11 = saved ar.pfs
301 * r15 = system call #
302 * b0 = saved return address
303 * b6 = return address
304 * On exit:
305 * r11 = saved ar.pfs
306 * r15 = system call #
307 * b0 = saved return address
308 * all other "scratch" registers: undefined
309 * all "preserved" registers: same as on entry
310 */
312 GLOBAL_ENTRY(__kernel_syscall_via_epc)
313 .prologue
314 .altrp b6
315 .body
316 {
317 /*
318 * Note: the kernel cannot assume that the first two instructions in this
319 * bundle get executed. The remaining code must be safe even if
320 * they do not get executed.
321 */
322 adds r17=-1024,r15 // A
323 mov r10=0 // A default to successful syscall execution
324 epc // B causes split-issue
325 }
326 ;;
327 RSM_PSR_BE_I(r20, r22) // M2 (5 cyc to srlz.d)
328 LOAD_FSYSCALL_TABLE(r14) // X
329 ;;
330 mov r16=IA64_KR(CURRENT) // M2 (12 cyc)
331 shladd r18=r17,3,r14 // A
332 mov r19=NR_syscalls-1 // A
333 ;;
334 lfetch [r18] // M0|1
335 MOV_FROM_PSR(p0, r29, r8) // M2 (12 cyc)
336 // If r17 is a NaT, p6 will be zero
337 cmp.geu p6,p7=r19,r17 // A (sysnr > 0 && sysnr < 1024+NR_syscalls)?
338 ;;
339 mov r21=ar.fpsr // M2 (12 cyc)
340 tnat.nz p10,p9=r15 // I0
341 mov.i r26=ar.pfs // I0 (would stall anyhow due to srlz.d...)
342 ;;
343 srlz.d // M0 (forces split-issue) ensure PSR.BE==0
344 (p6) ld8 r18=[r18] // M0|1
345 nop.i 0
346 ;;
347 nop.m 0
348 (p6) tbit.z.unc p8,p0=r18,0 // I0 (dual-issues with "mov b7=r18"!)
349 nop.i 0
350 ;;
351 SSM_PSR_I(p8, p14, r25)
352 (p6) mov b7=r18 // I0
353 (p8) br.dptk.many b7 // B
355 mov r27=ar.rsc // M2 (12 cyc)
356 /*
357 * brl.cond doesn't work as intended because the linker would convert this branch
358 * into a branch to a PLT. Perhaps there will be a way to avoid this with some
359 * future version of the linker. In the meantime, we just use an indirect branch
360 * instead.
361 */
362 #ifdef CONFIG_ITANIUM
363 (p6) add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry
364 ;;
365 (p6) ld8 r14=[r14] // r14 <- fsys_bubble_down
366 ;;
367 (p6) mov b7=r14
368 (p6) br.sptk.many b7
369 #else
370 BRL_COND_FSYS_BUBBLE_DOWN(p6)
371 #endif
372 SSM_PSR_I(p0, p14, r10)
373 mov r10=-1
374 (p10) mov r8=EINVAL
375 (p9) mov r8=ENOSYS
376 FSYS_RETURN
378 #ifdef CONFIG_PARAVIRT
379 /*
380 * padd to make the size of this symbol constant
381 * independent of paravirtualization.
382 */
383 .align PAGE_SIZE / 8
384 #endif
385 END(__kernel_syscall_via_epc)