306 lines
7.9 KiB
ArmAsm
306 lines
7.9 KiB
ArmAsm
/*
|
|
* wuf.S: Window underflow trap handler for the Sparc.
|
|
*
|
|
* Copyright (C) 1995 David S. Miller
|
|
*/
|
|
|
|
#include <asm/contregs.h>
|
|
#include <asm/page.h>
|
|
#include <asm/ptrace.h>
|
|
#include <asm/psr.h>
|
|
#include <asm/smp.h>
|
|
#include <asm/asi.h>
|
|
#include <asm/winmacro.h>
|
|
#include <asm/asmmacro.h>
|
|
#include <asm/thread_info.h>
|
|
|
|
/* Just like the overflow handler we define macros for registers
|
|
* with fixed meanings in this routine.
|
|
*/
|
|
#define t_psr l0
|
|
#define t_pc l1
|
|
#define t_npc l2
|
|
#define t_wim l3
|
|
/* Don't touch the above registers or else you die horribly... */
|
|
|
|
/* Now macros for the available scratch registers in this routine. */
|
|
#define twin_tmp1 l4
|
|
#define twin_tmp2 l5
|
|
|
|
#define curptr g6
|
|
|
|
.text
|
|
.align 4
|
|
|
|
/* The trap entry point has executed the following:
|
|
*
|
|
* rd %psr, %l0
|
|
* rd %wim, %l3
|
|
* b fill_window_entry
|
|
* andcc %l0, PSR_PS, %g0
|
|
*/
|
|
|
|
/* Datum current_thread_info->uwinmask contains at all times a bitmask
|
|
* where if any user windows are active, at least one bit will
|
|
* be set in to mask. If no user windows are active, the bitmask
|
|
* will be all zeroes.
|
|
*/
|
|
|
|
/* To get an idea of what has just happened to cause this
|
|
* trap take a look at this diagram:
|
|
*
|
|
* 1 2 3 4 <-- Window number
|
|
* ----------
|
|
* T O W I <-- Symbolic name
|
|
*
|
|
* O == the window that execution was in when
|
|
* the restore was attempted
|
|
*
|
|
* T == the trap itself has save'd us into this
|
|
* window
|
|
*
|
|
* W == this window is the one which is now invalid
|
|
* and must be made valid plus loaded from the
|
|
* stack
|
|
*
|
|
* I == this window will be the invalid one when we
|
|
* are done and return from trap if successful
|
|
*/
|
|
|
|
/* BEGINNING OF PATCH INSTRUCTIONS */
|
|
|
|
/* On 7-window Sparc the boot code patches fnwin_patch1
|
|
* with the following instruction.
|
|
*/
|
|
.globl fnwin_patch1_7win, fnwin_patch2_7win
|
|
fnwin_patch1_7win: srl %t_wim, 6, %twin_tmp2
|
|
fnwin_patch2_7win: and %twin_tmp1, 0x7f, %twin_tmp1
|
|
/* END OF PATCH INSTRUCTIONS */
|
|
|
|
.globl fill_window_entry, fnwin_patch1, fnwin_patch2
|
|
fill_window_entry:
|
|
/* LOCATION: Window 'T' */
|
|
|
|
/* Compute what the new %wim is going to be if we retrieve
|
|
* the proper window off of the stack.
|
|
*/
|
|
sll %t_wim, 1, %twin_tmp1
|
|
fnwin_patch1: srl %t_wim, 7, %twin_tmp2
|
|
or %twin_tmp1, %twin_tmp2, %twin_tmp1
|
|
fnwin_patch2: and %twin_tmp1, 0xff, %twin_tmp1
|
|
|
|
wr %twin_tmp1, 0x0, %wim /* Make window 'I' invalid */
|
|
|
|
andcc %t_psr, PSR_PS, %g0
|
|
be fwin_from_user
|
|
restore %g0, %g0, %g0 /* Restore to window 'O' */
|
|
|
|
/* Trapped from kernel, we trust that the kernel does not
|
|
* 'over restore' sorta speak and just grab the window
|
|
* from the stack and return. Easy enough.
|
|
*/
|
|
fwin_from_kernel:
|
|
/* LOCATION: Window 'O' */
|
|
|
|
restore %g0, %g0, %g0
|
|
|
|
/* LOCATION: Window 'W' */
|
|
|
|
LOAD_WINDOW(sp) /* Load it up */
|
|
|
|
/* Spin the wheel... */
|
|
save %g0, %g0, %g0
|
|
save %g0, %g0, %g0
|
|
/* I'd like to buy a vowel please... */
|
|
|
|
/* LOCATION: Window 'T' */
|
|
|
|
/* Now preserve the condition codes in %psr, pause, and
|
|
* return from trap. This is the simplest case of all.
|
|
*/
|
|
wr %t_psr, 0x0, %psr
|
|
WRITE_PAUSE
|
|
|
|
jmp %t_pc
|
|
rett %t_npc
|
|
|
|
fwin_from_user:
|
|
/* LOCATION: Window 'O' */
|
|
|
|
restore %g0, %g0, %g0 /* Restore to window 'W' */
|
|
|
|
/* LOCATION: Window 'W' */
|
|
|
|
/* Branch to the stack validation routine */
|
|
b srmmu_fwin_stackchk
|
|
andcc %sp, 0x7, %g0
|
|
|
|
#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
|
|
|
|
fwin_user_stack_is_bolixed:
|
|
/* LOCATION: Window 'W' */
|
|
|
|
/* Place a pt_regs frame on the kernel stack, save back
|
|
* to the trap window and call c-code to deal with this.
|
|
*/
|
|
LOAD_CURRENT(l4, l5)
|
|
|
|
sethi %hi(STACK_OFFSET), %l5
|
|
or %l5, %lo(STACK_OFFSET), %l5
|
|
add %l4, %l5, %l5
|
|
|
|
/* Store globals into pt_regs frame. */
|
|
STORE_PT_GLOBALS(l5)
|
|
STORE_PT_YREG(l5, g3)
|
|
|
|
/* Save current in a global while we change windows. */
|
|
mov %l4, %curptr
|
|
|
|
save %g0, %g0, %g0
|
|
|
|
/* LOCATION: Window 'O' */
|
|
|
|
rd %psr, %g3 /* Read %psr in live user window */
|
|
mov %fp, %g4 /* Save bogus frame pointer. */
|
|
|
|
save %g0, %g0, %g0
|
|
|
|
/* LOCATION: Window 'T' */
|
|
|
|
sethi %hi(STACK_OFFSET), %l5
|
|
or %l5, %lo(STACK_OFFSET), %l5
|
|
add %curptr, %l5, %sp
|
|
|
|
/* Build rest of pt_regs. */
|
|
STORE_PT_INS(sp)
|
|
STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)
|
|
|
|
/* re-set trap time %wim value */
|
|
wr %t_wim, 0x0, %wim
|
|
|
|
/* Fix users window mask and buffer save count. */
|
|
mov 0x1, %g5
|
|
sll %g5, %g3, %g5
|
|
st %g5, [%curptr + TI_UWINMASK] ! one live user window still
|
|
st %g0, [%curptr + TI_W_SAVED] ! no windows in the buffer
|
|
|
|
wr %t_psr, PSR_ET, %psr ! enable traps
|
|
nop
|
|
call window_underflow_fault
|
|
mov %g4, %o0
|
|
|
|
b ret_trap_entry
|
|
clr %l6
|
|
|
|
fwin_user_stack_is_ok:
|
|
/* LOCATION: Window 'W' */
|
|
|
|
/* The users stack area is kosher and mapped, load the
|
|
* window and fall through to the finish up routine.
|
|
*/
|
|
LOAD_WINDOW(sp)
|
|
|
|
/* Round and round she goes... */
|
|
save %g0, %g0, %g0 /* Save to window 'O' */
|
|
save %g0, %g0, %g0 /* Save to window 'T' */
|
|
/* Where she'll trap nobody knows... */
|
|
|
|
/* LOCATION: Window 'T' */
|
|
|
|
fwin_user_finish_up:
|
|
/* LOCATION: Window 'T' */
|
|
|
|
wr %t_psr, 0x0, %psr
|
|
WRITE_PAUSE
|
|
|
|
jmp %t_pc
|
|
rett %t_npc
|
|
|
|
/* Here come the architecture specific checks for stack.
|
|
* mappings. Note that unlike the window overflow handler
|
|
* we only need to check whether the user can read from
|
|
* the appropriate addresses. Also note that we are in
|
|
* an invalid window which will be loaded, and this means
|
|
* that until we actually load the window up we are free
|
|
* to use any of the local registers contained within.
|
|
*
|
|
* On success these routine branch to fwin_user_stack_is_ok
|
|
* if the area at %sp is user readable and the window still
|
|
* needs to be loaded, else fwin_user_finish_up if the
|
|
* routine has done the loading itself. On failure (bogus
|
|
* user stack) the routine shall branch to the label called
|
|
* fwin_user_stack_is_bolixed.
|
|
*
|
|
* Contrary to the arch-specific window overflow stack
|
|
* check routines in wof.S, these routines are free to use
|
|
* any of the local registers they want to as this window
|
|
* does not belong to anyone at this point, however the
|
|
* outs and ins are still verboten as they are part of
|
|
* 'someone elses' window possibly.
|
|
*/
|
|
|
|
.globl srmmu_fwin_stackchk
|
|
srmmu_fwin_stackchk:
|
|
/* LOCATION: Window 'W' */
|
|
|
|
/* Caller did 'andcc %sp, 0x7, %g0' */
|
|
bne fwin_user_stack_is_bolixed
|
|
sethi %hi(PAGE_OFFSET), %l5
|
|
|
|
/* Check if the users stack is in kernel vma, then our
|
|
* trial and error technique below would succeed for
|
|
* the 'wrong' reason.
|
|
*/
|
|
mov AC_M_SFSR, %l4
|
|
cmp %l5, %sp
|
|
bleu fwin_user_stack_is_bolixed
|
|
lda [%l4] ASI_M_MMUREGS, %g0 ! clear fault status
|
|
|
|
/* The technique is, turn off faults on this processor,
|
|
* just let the load rip, then check the sfsr to see if
|
|
* a fault did occur. Then we turn on fault traps again
|
|
* and branch conditionally based upon what happened.
|
|
*/
|
|
lda [%g0] ASI_M_MMUREGS, %l5 ! read mmu-ctrl reg
|
|
or %l5, 0x2, %l5 ! turn on no-fault bit
|
|
sta %l5, [%g0] ASI_M_MMUREGS ! store it
|
|
|
|
/* Cross fingers and go for it. */
|
|
LOAD_WINDOW(sp)
|
|
|
|
/* A penny 'saved'... */
|
|
save %g0, %g0, %g0
|
|
save %g0, %g0, %g0
|
|
/* Is a BADTRAP earned... */
|
|
|
|
/* LOCATION: Window 'T' */
|
|
|
|
lda [%g0] ASI_M_MMUREGS, %twin_tmp1 ! load mmu-ctrl again
|
|
andn %twin_tmp1, 0x2, %twin_tmp1 ! clear no-fault bit
|
|
sta %twin_tmp1, [%g0] ASI_M_MMUREGS ! store it
|
|
|
|
mov AC_M_SFAR, %twin_tmp2
|
|
lda [%twin_tmp2] ASI_M_MMUREGS, %g0 ! read fault address
|
|
|
|
mov AC_M_SFSR, %twin_tmp2
|
|
lda [%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2 ! read fault status
|
|
andcc %twin_tmp2, 0x2, %g0 ! did fault occur?
|
|
|
|
bne 1f ! yep, cleanup
|
|
nop
|
|
|
|
wr %t_psr, 0x0, %psr
|
|
nop
|
|
b fwin_user_finish_up + 0x4
|
|
nop
|
|
|
|
/* Did I ever tell you about my window lobotomy?
|
|
* anyways... fwin_user_stack_is_bolixed expects
|
|
* to be in window 'W' so make it happy or else
|
|
* we watchdog badly.
|
|
*/
|
|
1:
|
|
restore %g0, %g0, %g0
|
|
b fwin_user_stack_is_bolixed ! oh well
|
|
restore %g0, %g0, %g0
|