Add a seatbelt to the Nested TLB Fault handler to give us a chance
to panic when we have an unexpected TLB fault while interrupt collection is disabled. Use a token rather than the actual address of the restart point to avoid the need for the movl instruction. The token is arbitrary. For the drummers: it's based on a single paradiddle.
This commit is contained in:
Marcel Moolenaar
parent
01d1a6c355
commit
02b5a86f38
@ -28,11 +28,20 @@
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kstack_pages.h"
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#include "opt_xtrace.h"
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#include <machine/pte.h>
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#include <assym.s>
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/*
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* Nested TLB restart tokens. These are used by the
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* nested TLB handler for jumping back to the code
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* where the nested TLB was caused.
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*/
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#define NTLBRT_SAVE 0x12c12c
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#define NTLBRT_RESTORE 0x12c12d
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/*
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* ar.k7 = kernel memory stack
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* ar.k6 = kernel register stack
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@ -140,9 +149,10 @@ ENTRY_NOPROFILE(exception_save, 0)
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add r31=8,r30
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;;
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}
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{ .mlx
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{ .mib
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mov r22=cr.iip
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movl r26=exception_save_restart
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addl r29=NTLBRT_SAVE,r0 // 22-bit restart token.
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nop 0
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;;
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}
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@ -157,7 +167,7 @@ ENTRY_NOPROFILE(exception_save, 0)
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* that are currently alive:
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* r16,r17=arguments
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* r18=pr, r19=length, r20=unat, r21=rsc, r22=iip, r23=TOS
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* r26=restart point
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* r29=restart point
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* r30,r31=trapframe pointers
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* p14,p15=memory stack switch
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*/
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@ -544,7 +554,7 @@ ENTRY_NOPROFILE(exception_restore, 0)
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ld8 r21=[r31],24 // rnat
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mov ar.pfs=r28
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;;
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ld8.fill r29=[r30],16 // tp
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ld8.fill r26=[r30],16 // tp
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ld8 r22=[r31],16 // rsc
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;;
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{ .mmi
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@ -555,21 +565,21 @@ ENTRY_NOPROFILE(exception_restore, 0)
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}
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{ .mmi
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ld8.fill r1=[r30],16 // gp
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ld8 r25=[r31],16 // ndirty
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ld8 r27=[r31],16 // ndirty
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cmp.le p14,p15=5,r28
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;;
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}
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{ .mmb
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ld8 r26=[r30] // cfm
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ld8 r25=[r30] // cfm
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ld8 r19=[r31] // ip
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nop 0
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;;
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}
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{ .mib
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{ .mii
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// Switch register stack
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alloc r30=ar.pfs,0,0,0,0 // discard current frame
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shl r31=r25,16 // value for ar.rsc
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nop 0
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shl r31=r27,16 // value for ar.rsc
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(p15) mov r13=r26
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;;
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}
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// The loadrs can fault if the backing store is not currently
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@ -580,7 +590,7 @@ ENTRY_NOPROFILE(exception_restore, 0)
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{ .mmi
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mov ar.rsc=r31 // setup for loadrs
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mov ar.k7=r16
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(p15) mov r13=r29
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addl r29=NTLBRT_RESTORE,r0 // 22-bit restart token
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;;
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}
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exception_restore_restart:
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@ -611,7 +621,7 @@ exception_restore_restart:
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}
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{ .mmi
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mov cr.ipsr=r24
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mov cr.ifs=r26
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mov cr.ifs=r25
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mov pr=r18,0x1ffff
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;;
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}
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@ -944,7 +954,7 @@ IVT_ENTRY(Data_Nested_TLB, 0x1400)
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}
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{ .mii
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ld8 r27=[r27] // dir L0 page
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extr.u r29=r30,2*PAGE_SHIFT-5, PAGE_SHIFT-3 // dir L1 index
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extr.u r26=r30,2*PAGE_SHIFT-5, PAGE_SHIFT-3 // dir L1 index
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;;
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dep r27=0,r27,61,3
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;;
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@ -957,16 +967,16 @@ IVT_ENTRY(Data_Nested_TLB, 0x1400)
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;;
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}
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{ .mmi
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shladd r27=r29,3,r27
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shladd r27=r26,3,r27
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;;
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mov r29=rr[r30]
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mov r26=rr[r30]
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dep r27=0,r27,61,3
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;;
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}
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{ .mii
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ld8 r27=[r27] // pte page
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shl r28=r28,5
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dep r29=0,r29,0,2
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dep r26=0,r26,0,2
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;;
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}
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{ .mmi
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@ -979,28 +989,54 @@ IVT_ENTRY(Data_Nested_TLB, 0x1400)
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{ .mmi
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ld8 r28=[r27] // pte
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;;
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mov cr.itir=r29
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mov cr.itir=r26
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or r28=PTE_DIRTY+PTE_ACCESSED,r28
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;;
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}
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{ .mlx
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{ .mmi
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st8 [r27]=r28
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movl r29=exception_save_restart
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;;
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addl r26=NTLBRT_SAVE,r0
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addl r27=NTLBRT_RESTORE,r0
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}
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{ .mmi
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itc.d r28
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;;
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ssm psr.dt
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cmp.eq p12,p13=r26,r29
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cmp.eq p12,p0=r29,r26
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;;
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}
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{ .mbb
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{ .mib
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srlz.d
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cmp.eq p13,p0=r29,r27
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(p12) br.sptk exception_save_restart
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;;
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}
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{ .mib
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nop 0
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nop 0
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(p13) br.sptk exception_restore_restart
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;;
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}
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{ .mlx
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mov r26=ar.bsp
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movl r27=kstack
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;;
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}
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{ .mib
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mov r28=sp
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addl r27=KSTACK_PAGES*PAGE_SIZE-16,r0
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nop 0
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;;
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}
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{ .mmi
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mov sp=r27
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;;
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mov r27=ar.bspstore
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nop 0
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;;
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}
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CALL(trap, 5, r30)
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IVT_END(Data_Nested_TLB)
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IVT_ENTRY(Instruction_Key_Miss, 0x1800)
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@ -414,11 +414,9 @@ trap(int vector, struct trapframe *tf)
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case IA64_VEC_NESTED_DTLB:
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/*
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* We never call trap() with this vector. We may want to
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* do that in the future in case the nested TLB handler
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* could not find the translation it needs. In that case
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* we could switch to a special (hardwired) stack and
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* come here to produce a nice panic().
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* When the nested TLB handler encounters an unexpected
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* condition, it'll switch to the backup stack and transfer
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* here. All we need to do is panic.
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*/
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trap_panic(vector, tf);
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break;
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