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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ia64/kernel/gate.S
downloadlinux-stericsson-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/ia64/kernel/gate.S')
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diff --git a/arch/ia64/kernel/gate.S b/arch/ia64/kernel/gate.S
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+/*
+ * 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) 1999-2003 Hewlett-Packard Co
+ * David Mosberger-Tang <davidm@hpl.hp.com>
+ */
+
+#include <linux/config.h>
+
+#include <asm/asmmacro.h>
+#include <asm/errno.h>
+#include <asm/offsets.h>
+#include <asm/sigcontext.h>
+#include <asm/system.h>
+#include <asm/unistd.h>
+
+/*
+ * We can't easily refer to symbols inside the kernel. To avoid full runtime relocation,
+ * complications with the linker (which likes to create PLT stubs for branches
+ * to targets outside the shared object) and to avoid multi-phase kernel builds, we
+ * simply create minimalistic "patch lists" in special ELF sections.
+ */
+ .section ".data.patch.fsyscall_table", "a"
+ .previous
+#define LOAD_FSYSCALL_TABLE(reg) \
+[1:] movl reg=0; \
+ .xdata4 ".data.patch.fsyscall_table", 1b-.
+
+ .section ".data.patch.brl_fsys_bubble_down", "a"
+ .previous
+#define BRL_COND_FSYS_BUBBLE_DOWN(pr) \
+[1:](pr)brl.cond.sptk 0; \
+ .xdata4 ".data.patch.brl_fsys_bubble_down", 1b-.
+
+GLOBAL_ENTRY(__kernel_syscall_via_break)
+ .prologue
+ .altrp b6
+ .body
+ /*
+ * Note: for (fast) syscall restart to work, the break instruction must be
+ * the first one in the bundle addressed by syscall_via_break.
+ */
+{ .mib
+ break 0x100000
+ nop.i 0
+ br.ret.sptk.many b6
+}
+END(__kernel_syscall_via_break)
+
+/*
+ * On entry:
+ * r11 = saved ar.pfs
+ * r15 = system call #
+ * b0 = saved return address
+ * b6 = return address
+ * On exit:
+ * r11 = saved ar.pfs
+ * r15 = system call #
+ * b0 = saved return address
+ * all other "scratch" registers: undefined
+ * all "preserved" registers: same as on entry
+ */
+
+GLOBAL_ENTRY(__kernel_syscall_via_epc)
+ .prologue
+ .altrp b6
+ .body
+{
+ /*
+ * Note: the kernel cannot assume that the first two instructions in this
+ * bundle get executed. The remaining code must be safe even if
+ * they do not get executed.
+ */
+ adds r17=-1024,r15
+ mov r10=0 // default to successful syscall execution
+ epc
+}
+ ;;
+ rsm psr.be // note: on McKinley "rsm psr.be/srlz.d" is slightly faster than "rum psr.be"
+ LOAD_FSYSCALL_TABLE(r14)
+
+ mov r16=IA64_KR(CURRENT) // 12 cycle read latency
+ tnat.nz p10,p9=r15
+ mov r19=NR_syscalls-1
+ ;;
+ shladd r18=r17,3,r14
+
+ srlz.d
+ cmp.ne p8,p0=r0,r0 // p8 <- FALSE
+ /* Note: if r17 is a NaT, p6 will be set to zero. */
+ cmp.geu p6,p7=r19,r17 // (syscall > 0 && syscall < 1024+NR_syscalls)?
+ ;;
+(p6) ld8 r18=[r18]
+ mov r21=ar.fpsr
+ add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry
+ ;;
+(p6) mov b7=r18
+(p6) tbit.z p8,p0=r18,0
+(p8) br.dptk.many b7
+
+(p6) rsm psr.i
+ mov r27=ar.rsc
+ mov r26=ar.pfs
+ ;;
+ mov r29=psr // read psr (12 cyc load latency)
+/*
+ * brl.cond doesn't work as intended because the linker would convert this branch
+ * into a branch to a PLT. Perhaps there will be a way to avoid this with some
+ * future version of the linker. In the meantime, we just use an indirect branch
+ * instead.
+ */
+#ifdef CONFIG_ITANIUM
+(p6) ld8 r14=[r14] // r14 <- fsys_bubble_down
+ ;;
+(p6) mov b7=r14
+(p6) br.sptk.many b7
+#else
+ BRL_COND_FSYS_BUBBLE_DOWN(p6)
+#endif
+
+ mov r10=-1
+(p10) mov r8=EINVAL
+(p9) mov r8=ENOSYS
+ FSYS_RETURN
+END(__kernel_syscall_via_epc)
+
+# 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_IP_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.
+ */
+
+#define SIGTRAMP_SAVES \
+ .unwabi 3, 's'; /* mark this as a sigtramp handler (saves scratch regs) */ \
+ .unwabi @svr4, 's'; /* backwards compatibility with old unwinders (remove in v2.7) */ \
+ .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; \
+ .savesp ar.pfs, CFM_OFF+SIGCONTEXT_OFF; \
+ .vframesp SP_OFF+SIGCONTEXT_OFF
+
+GLOBAL_ENTRY(__kernel_sigtramp)
+ // describe the state that is active when we get here:
+ .prologue
+ SIGTRAMP_SAVES
+ .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 p1,p0=r15,r0 // do we need to switch rbs? (note: pr is saved by kernel)
+ mov.m r9=ar.bsp // fetch ar.bsp
+ .spillsp.p p1, ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
+(p1) br.cond.spnt setup_rbs // yup -> (clobbers p8, r14-r16, and r18-r20)
+back_from_setup_rbs:
+ alloc r8=ar.pfs,0,0,3,0
+ 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 // save sc_ar_bsp
+ adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp
+ adds base1=(FR6_OFF+16+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] // fetch sc_ar_bsp
+ mov r14=ar.bsp
+ ;;
+ cmp.ne p1,p0=r14,r15 // do we need to restore the rbs?
+(p1) br.cond.spnt restore_rbs // yup -> (clobbers r14-r18, f6 & f7)
+ ;;
+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
+ .restore sp // pop .prologue
+ break __BREAK_SYSCALL
+
+ .prologue
+ SIGTRAMP_SAVES
+setup_rbs:
+ mov ar.rsc=0 // put RSE into enforced lazy mode
+ ;;
+ .save ar.rnat, r19
+ mov r19=ar.rnat // save RNaT before switching backing store area
+ adds r14=(RNAT_OFF+SIGCONTEXT_OFF),sp
+
+ mov r18=ar.bspstore
+ mov ar.bspstore=r15 // switch over to new register backing store area
+ ;;
+
+ .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
+ st8 [r14]=r19 // save sc_ar_rnat
+ .body
+ mov.m r16=ar.bsp // sc_loadrs <- (new bsp - new bspstore) << 16
+ adds r14=(LOADRS_OFF+SIGCONTEXT_OFF),sp
+ ;;
+ invala
+ sub r15=r16,r15
+ extr.u r20=r18,3,6
+ ;;
+ mov ar.rsc=0xf // set RSE into eager mode, pl 3
+ cmp.eq p8,p0=63,r20
+ shl r15=r15,16
+ ;;
+ st8 [r14]=r15 // save sc_loadrs
+(p8) st8 [r18]=r19 // if bspstore points at RNaT slot, store RNaT there now
+ .restore sp // pop .prologue
+ br.cond.sptk back_from_setup_rbs
+
+ .prologue
+ SIGTRAMP_SAVES
+ .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF
+ .body
+restore_rbs:
+ // On input:
+ // r14 = bsp1 (bsp at the time of return from signal handler)
+ // r15 = bsp0 (bsp at the time the signal occurred)
+ //
+ // Here, we need to calculate bspstore0, the value that ar.bspstore needs
+ // to be set to, based on bsp0 and the size of the dirty partition on
+ // the alternate stack (sc_loadrs >> 16). This can be done with the
+ // following algorithm:
+ //
+ // bspstore0 = rse_skip_regs(bsp0, -rse_num_regs(bsp1 - (loadrs >> 19), bsp1));
+ //
+ // This is what the code below does.
+ //
+ alloc r2=ar.pfs,0,0,0,0 // alloc null frame
+ adds r16=(LOADRS_OFF+SIGCONTEXT_OFF),sp
+ adds r18=(RNAT_OFF+SIGCONTEXT_OFF),sp
+ ;;
+ ld8 r17=[r16]
+ ld8 r16=[r18] // get new rnat
+ extr.u r18=r15,3,6 // r18 <- rse_slot_num(bsp0)
+ ;;
+ mov ar.rsc=r17 // put RSE into enforced lazy mode
+ shr.u r17=r17,16
+ ;;
+ sub r14=r14,r17 // r14 (bspstore1) <- bsp1 - (sc_loadrs >> 16)
+ shr.u r17=r17,3 // r17 <- (sc_loadrs >> 19)
+ ;;
+ loadrs // restore dirty partition
+ extr.u r14=r14,3,6 // r14 <- rse_slot_num(bspstore1)
+ ;;
+ add r14=r14,r17 // r14 <- rse_slot_num(bspstore1) + (sc_loadrs >> 19)
+ ;;
+ shr.u r14=r14,6 // r14 <- (rse_slot_num(bspstore1) + (sc_loadrs >> 19))/0x40
+ ;;
+ sub r14=r14,r17 // r14 <- -rse_num_regs(bspstore1, bsp1)
+ movl r17=0x8208208208208209
+ ;;
+ add r18=r18,r14 // r18 (delta) <- rse_slot_num(bsp0) - rse_num_regs(bspstore1,bsp1)
+ setf.sig f7=r17
+ cmp.lt p7,p0=r14,r0 // p7 <- (r14 < 0)?
+ ;;
+(p7) adds r18=-62,r18 // delta -= 62
+ ;;
+ setf.sig f6=r18
+ ;;
+ xmpy.h f6=f6,f7
+ ;;
+ getf.sig r17=f6
+ ;;
+ add r17=r17,r18
+ shr r18=r18,63
+ ;;
+ shr r17=r17,5
+ ;;
+ sub r17=r17,r18 // r17 = delta/63
+ ;;
+ add r17=r14,r17 // r17 <- delta/63 - rse_num_regs(bspstore1, bsp1)
+ ;;
+ shladd r15=r17,3,r15 // r15 <- bsp0 + 8*(delta/63 - rse_num_regs(bspstore1, bsp1))
+ ;;
+ mov ar.bspstore=r15 // switch back to old register backing store area
+ ;;
+ mov ar.rnat=r16 // 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(__kernel_sigtramp)