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alistair23-linux/arch/ia64/kernel/gate.S
Luis R. Rodriguez e55645ec57 ia64: remove paravirt code 
All the ia64 pvops code is now dead code since both
xen and kvm support have been ripped out [0] [1]. Just
that no one had troubled to rip this stuff out. The only
useful remaining pieces were the old pvops docs but that
was recently also generalized and moved out from ia64 [2].

This has been run time tested on an ia64 Madison system.

[0] 003f7de625 "KVM: ia64: remove" since v3.19-rc1
[1] d52eefb47d "ia64/xen: Remove Xen support for ia64" since v3.14-rc1
[2] "virtual: Documentation: simplify and generalize paravirt_ops.txt"

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2015-06-10 14:26:32 -07:00

380 lines
11 KiB
ArmAsm
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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 <asm/asmmacro.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>
#include <asm/sigcontext.h>
#include <asm/unistd.h>
#include <asm/kregs.h>
#include <asm/page.h>
#include <asm/native/inst.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)
# 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)
/*
* 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 // A
mov r10=0 // A default to successful syscall execution
epc // B causes split-issue
}
;;
RSM_PSR_BE_I(r20, r22) // M2 (5 cyc to srlz.d)
LOAD_FSYSCALL_TABLE(r14) // X
;;
mov r16=IA64_KR(CURRENT) // M2 (12 cyc)
shladd r18=r17,3,r14 // A
mov r19=NR_syscalls-1 // A
;;
lfetch [r18] // M0|1
MOV_FROM_PSR(p0, r29, r8) // M2 (12 cyc)
// If r17 is a NaT, p6 will be zero
cmp.geu p6,p7=r19,r17 // A (sysnr > 0 && sysnr < 1024+NR_syscalls)?
;;
mov r21=ar.fpsr // M2 (12 cyc)
tnat.nz p10,p9=r15 // I0
mov.i r26=ar.pfs // I0 (would stall anyhow due to srlz.d...)
;;
srlz.d // M0 (forces split-issue) ensure PSR.BE==0
(p6) ld8 r18=[r18] // M0|1
nop.i 0
;;
nop.m 0
(p6) tbit.z.unc p8,p0=r18,0 // I0 (dual-issues with "mov b7=r18"!)
nop.i 0
;;
SSM_PSR_I(p8, p14, r25)
(p6) mov b7=r18 // I0
(p8) br.dptk.many b7 // B
mov r27=ar.rsc // M2 (12 cyc)
/*
* 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) add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry
;;
(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
SSM_PSR_I(p0, p14, r10)
mov r10=-1
(p10) mov r8=EINVAL
(p9) mov r8=ENOSYS
FSYS_RETURN
END(__kernel_syscall_via_epc)
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