/* * This file contains the code that gets mapped at the upper end of each task's text * region. For now, it contains the signal trampoline code only. * * Copyright (C) 1999-2001 Hewlett-Packard Co * David Mosberger-Tang */ #include #include #include #include #include #include .section .text.gate,"ax" # define ARG0_OFF (16 + IA64_SIGFRAME_ARG0_OFFSET) # define ARG1_OFF (16 + IA64_SIGFRAME_ARG1_OFFSET) # define ARG2_OFF (16 + IA64_SIGFRAME_ARG2_OFFSET) # define SIGHANDLER_OFF (16 + IA64_SIGFRAME_HANDLER_OFFSET) # define SIGCONTEXT_OFF (16 + IA64_SIGFRAME_SIGCONTEXT_OFFSET) # define FLAGS_OFF IA64_SIGCONTEXT_FLAGS_OFFSET # define CFM_OFF IA64_SIGCONTEXT_CFM_OFFSET # define FR6_OFF IA64_SIGCONTEXT_FR6_OFFSET # define BSP_OFF IA64_SIGCONTEXT_AR_BSP_OFFSET # define RNAT_OFF IA64_SIGCONTEXT_AR_RNAT_OFFSET # define UNAT_OFF IA64_SIGCONTEXT_AR_UNAT_OFFSET # define FPSR_OFF IA64_SIGCONTEXT_AR_FPSR_OFFSET # define PR_OFF IA64_SIGCONTEXT_PR_OFFSET # define RP_OFF IA64_SIGCONTEXT_B0_OFFSET # define SP_OFF IA64_SIGCONTEXT_R12_OFFSET # define RBS_BASE_OFF IA64_SIGCONTEXT_RBS_BASE_OFFSET # define LOADRS_OFF IA64_SIGCONTEXT_LOADRS_OFFSET # define base0 r2 # define base1 r3 /* * When we get here, the memory stack looks like this: * * +===============================+ * | | * // struct sigframe // * | | * +-------------------------------+ <-- sp+16 * | 16 byte of scratch | * | space | * +-------------------------------+ <-- sp * * The register stack looks _exactly_ the way it looked at the time the signal * occurred. In other words, we're treading on a potential mine-field: each * incoming general register may be a NaT value (including sp, in which case the * process ends up dying with a SIGSEGV). * * The first thing need to do is a cover to get the registers onto the backing * store. Once that is done, we invoke the signal handler which may modify some * of the machine state. After returning from the signal handler, we return * control to the previous context by executing a sigreturn system call. A signal * handler may call the rt_sigreturn() function to directly return to a given * sigcontext. However, the user-level sigreturn() needs to do much more than * calling the rt_sigreturn() system call as it needs to unwind the stack to * restore preserved registers that may have been saved on the signal handler's * call stack. */ GLOBAL_ENTRY(ia64_sigtramp) // describe the state that is active when we get here: .prologue .unwabi @svr4, 's' // mark this as a sigtramp handler (saves scratch regs) .savesp ar.unat, UNAT_OFF+SIGCONTEXT_OFF .savesp ar.fpsr, FPSR_OFF+SIGCONTEXT_OFF .savesp pr, PR_OFF+SIGCONTEXT_OFF .savesp rp, RP_OFF+SIGCONTEXT_OFF .vframesp SP_OFF+SIGCONTEXT_OFF .body .label_state 1 adds base0=SIGHANDLER_OFF,sp adds base1=RBS_BASE_OFF+SIGCONTEXT_OFF,sp br.call.sptk.many rp=1f 1: ld8 r17=[base0],(ARG0_OFF-SIGHANDLER_OFF) // get pointer to signal handler's plabel ld8 r15=[base1] // get address of new RBS base (or NULL) cover // push args in interrupted frame onto backing store ;; cmp.ne p8,p0=r15,r0 // do we need to switch the rbs? mov.m r9=ar.bsp // fetch ar.bsp .spillsp.p p8, ar.rnat, RNAT_OFF+SIGCONTEXT_OFF (p8) br.cond.spnt setup_rbs // yup -> (clobbers r14, r15, and r16) back_from_setup_rbs: .spillreg ar.pfs, r8 alloc r8=ar.pfs,0,0,3,0 // get CFM0, EC0, and CPL0 into r8 ld8 out0=[base0],16 // load arg0 (signum) adds base1=(ARG1_OFF-(RBS_BASE_OFF+SIGCONTEXT_OFF)),base1 ;; ld8 out1=[base1] // load arg1 (siginfop) ld8 r10=[r17],8 // get signal handler entry point ;; ld8 out2=[base0] // load arg2 (sigcontextp) ld8 gp=[r17] // get signal handler's global pointer adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp ;; .spillsp ar.bsp, BSP_OFF+SIGCONTEXT_OFF st8 [base0]=r9,(CFM_OFF-BSP_OFF) // save sc_ar_bsp dep r8=0,r8,38,26 // clear EC0, CPL0 and reserved bits adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp ;; .spillsp ar.pfs, CFM_OFF st8 [base0]=r8 // save CFM0 adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp ;; stf.spill [base0]=f6,32 stf.spill [base1]=f7,32 ;; stf.spill [base0]=f8,32 stf.spill [base1]=f9,32 mov b6=r10 ;; stf.spill [base0]=f10,32 stf.spill [base1]=f11,32 ;; stf.spill [base0]=f12,32 stf.spill [base1]=f13,32 ;; stf.spill [base0]=f14,32 stf.spill [base1]=f15,32 br.call.sptk.many rp=b6 // call the signal handler .ret0: adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp ;; ld8 r15=[base0],(CFM_OFF-BSP_OFF) // fetch sc_ar_bsp and advance to CFM_OFF mov r14=ar.bsp ;; ld8 r8=[base0] // restore (perhaps modified) CFM0, EC0, and CPL0 cmp.ne p8,p0=r14,r15 // do we need to restore the rbs? (p8) br.cond.spnt restore_rbs // yup -> (clobbers r14 and r16) ;; back_from_restore_rbs: adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp ;; ldf.fill f6=[base0],32 ldf.fill f7=[base1],32 ;; ldf.fill f8=[base0],32 ldf.fill f9=[base1],32 ;; ldf.fill f10=[base0],32 ldf.fill f11=[base1],32 ;; ldf.fill f12=[base0],32 ldf.fill f13=[base1],32 ;; ldf.fill f14=[base0],32 ldf.fill f15=[base1],32 mov r15=__NR_rt_sigreturn break __BREAK_SYSCALL .body .copy_state 1 setup_rbs: mov ar.rsc=0 // put RSE into enforced lazy mode ;; .save ar.rnat, r16 mov r16=ar.rnat // save RNaT before switching backing store area adds r14=(RNAT_OFF+SIGCONTEXT_OFF),sp mov ar.bspstore=r15 // switch over to new register backing store area ;; .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF st8 [r14]=r16 // save sc_ar_rnat adds r14=(LOADRS_OFF+SIGCONTEXT_OFF),sp mov.m r16=ar.bsp // sc_loadrs <- (new bsp - new bspstore) << 16 ;; invala sub r15=r16,r15 ;; shl r15=r15,16 ;; st8 [r14]=r15 // save sc_loadrs mov ar.rsc=0xf // set RSE into eager mode, pl 3 br.cond.sptk back_from_setup_rbs .prologue .copy_state 1 .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF .body restore_rbs: alloc r2=ar.pfs,0,0,0,0 // alloc null frame adds r16=(LOADRS_OFF+SIGCONTEXT_OFF),sp ;; ld8 r14=[r16] adds r16=(RNAT_OFF+SIGCONTEXT_OFF),sp ;; mov ar.rsc=r14 // put RSE into enforced lazy mode ld8 r14=[r16] // get new rnat ;; loadrs // restore dirty partition ;; mov ar.bspstore=r15 // switch back to old register backing store area ;; mov ar.rnat=r14 // restore RNaT mov ar.rsc=0xf // (will be restored later on from sc_ar_rsc) // invala not necessary as that will happen when returning to user-mode br.cond.sptk back_from_restore_rbs END(ia64_sigtramp)