Revision 4f350c6dbcb9000e18907515ec8a7b205ac33c69 authored by Jim Mattson on 14 September 2017, 23:31:44 UTC, committed by Paolo Bonzini on 15 September 2017, 14:57:15 UTC
When emulating a nested VM-entry from L1 to L2, several control field validation checks are deferred to the hardware. Should one of these validation checks fail, vcpu_vmx_run will set the vmx->fail flag. When this happens, the L2 guest state is not loaded (even in part), and execution should continue in L1 with the next instruction after the VMLAUNCH/VMRESUME. The VMCS12 is not modified (except for the VM-instruction error field), the VMCS12 MSR save/load lists are not processed, and the CPU state is not loaded from the VMCS12 host area. Moreover, the vmcs02 exit reason is stale, so it should not be consulted for any reason. Signed-off-by: Jim Mattson <jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent b060ca3
memcpy_mck.S
/*
* Itanium 2-optimized version of memcpy and copy_user function
*
* Inputs:
* in0: destination address
* in1: source address
* in2: number of bytes to copy
* Output:
* for memcpy: return dest
* for copy_user: return 0 if success,
* or number of byte NOT copied if error occurred.
*
* Copyright (C) 2002 Intel Corp.
* Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com>
*/
#include <asm/asmmacro.h>
#include <asm/page.h>
#include <asm/export.h>
#define EK(y...) EX(y)
/* McKinley specific optimization */
#define retval r8
#define saved_pfs r31
#define saved_lc r10
#define saved_pr r11
#define saved_in0 r14
#define saved_in1 r15
#define saved_in2 r16
#define src0 r2
#define src1 r3
#define dst0 r17
#define dst1 r18
#define cnt r9
/* r19-r30 are temp for each code section */
#define PREFETCH_DIST 8
#define src_pre_mem r19
#define dst_pre_mem r20
#define src_pre_l2 r21
#define dst_pre_l2 r22
#define t1 r23
#define t2 r24
#define t3 r25
#define t4 r26
#define t5 t1 // alias!
#define t6 t2 // alias!
#define t7 t3 // alias!
#define n8 r27
#define t9 t5 // alias!
#define t10 t4 // alias!
#define t11 t7 // alias!
#define t12 t6 // alias!
#define t14 t10 // alias!
#define t13 r28
#define t15 r29
#define tmp r30
/* defines for long_copy block */
#define A 0
#define B (PREFETCH_DIST)
#define C (B + PREFETCH_DIST)
#define D (C + 1)
#define N (D + 1)
#define Nrot ((N + 7) & ~7)
/* alias */
#define in0 r32
#define in1 r33
#define in2 r34
GLOBAL_ENTRY(memcpy)
and r28=0x7,in0
and r29=0x7,in1
mov f6=f0
mov retval=in0
br.cond.sptk .common_code
;;
END(memcpy)
EXPORT_SYMBOL(memcpy)
GLOBAL_ENTRY(__copy_user)
.prologue
// check dest alignment
and r28=0x7,in0
and r29=0x7,in1
mov f6=f1
mov saved_in0=in0 // save dest pointer
mov saved_in1=in1 // save src pointer
mov retval=r0 // initialize return value
;;
.common_code:
cmp.gt p15,p0=8,in2 // check for small size
cmp.ne p13,p0=0,r28 // check dest alignment
cmp.ne p14,p0=0,r29 // check src alignment
add src0=0,in1
sub r30=8,r28 // for .align_dest
mov saved_in2=in2 // save len
;;
add dst0=0,in0
add dst1=1,in0 // dest odd index
cmp.le p6,p0 = 1,r30 // for .align_dest
(p15) br.cond.dpnt .memcpy_short
(p13) br.cond.dpnt .align_dest
(p14) br.cond.dpnt .unaligned_src
;;
// both dest and src are aligned on 8-byte boundary
.aligned_src:
.save ar.pfs, saved_pfs
alloc saved_pfs=ar.pfs,3,Nrot-3,0,Nrot
.save pr, saved_pr
mov saved_pr=pr
shr.u cnt=in2,7 // this much cache line
;;
cmp.lt p6,p0=2*PREFETCH_DIST,cnt
cmp.lt p7,p8=1,cnt
.save ar.lc, saved_lc
mov saved_lc=ar.lc
.body
add cnt=-1,cnt
add src_pre_mem=0,in1 // prefetch src pointer
add dst_pre_mem=0,in0 // prefetch dest pointer
;;
(p7) mov ar.lc=cnt // prefetch count
(p8) mov ar.lc=r0
(p6) br.cond.dpnt .long_copy
;;
.prefetch:
lfetch.fault [src_pre_mem], 128
lfetch.fault.excl [dst_pre_mem], 128
br.cloop.dptk.few .prefetch
;;
.medium_copy:
and tmp=31,in2 // copy length after iteration
shr.u r29=in2,5 // number of 32-byte iteration
add dst1=8,dst0 // 2nd dest pointer
;;
add cnt=-1,r29 // ctop iteration adjustment
cmp.eq p10,p0=r29,r0 // do we really need to loop?
add src1=8,src0 // 2nd src pointer
cmp.le p6,p0=8,tmp
;;
cmp.le p7,p0=16,tmp
mov ar.lc=cnt // loop setup
cmp.eq p16,p17 = r0,r0
mov ar.ec=2
(p10) br.dpnt.few .aligned_src_tail
;;
TEXT_ALIGN(32)
1:
EX(.ex_handler, (p16) ld8 r34=[src0],16)
EK(.ex_handler, (p16) ld8 r38=[src1],16)
EX(.ex_handler, (p17) st8 [dst0]=r33,16)
EK(.ex_handler, (p17) st8 [dst1]=r37,16)
;;
EX(.ex_handler, (p16) ld8 r32=[src0],16)
EK(.ex_handler, (p16) ld8 r36=[src1],16)
EX(.ex_handler, (p16) st8 [dst0]=r34,16)
EK(.ex_handler, (p16) st8 [dst1]=r38,16)
br.ctop.dptk.few 1b
;;
.aligned_src_tail:
EX(.ex_handler, (p6) ld8 t1=[src0])
mov ar.lc=saved_lc
mov ar.pfs=saved_pfs
EX(.ex_hndlr_s, (p7) ld8 t2=[src1],8)
cmp.le p8,p0=24,tmp
and r21=-8,tmp
;;
EX(.ex_hndlr_s, (p8) ld8 t3=[src1])
EX(.ex_handler, (p6) st8 [dst0]=t1) // store byte 1
and in2=7,tmp // remaining length
EX(.ex_hndlr_d, (p7) st8 [dst1]=t2,8) // store byte 2
add src0=src0,r21 // setting up src pointer
add dst0=dst0,r21 // setting up dest pointer
;;
EX(.ex_handler, (p8) st8 [dst1]=t3) // store byte 3
mov pr=saved_pr,-1
br.dptk.many .memcpy_short
;;
/* code taken from copy_page_mck */
.long_copy:
.rotr v[2*PREFETCH_DIST]
.rotp p[N]
mov src_pre_mem = src0
mov pr.rot = 0x10000
mov ar.ec = 1 // special unrolled loop
mov dst_pre_mem = dst0
add src_pre_l2 = 8*8, src0
add dst_pre_l2 = 8*8, dst0
;;
add src0 = 8, src_pre_mem // first t1 src
mov ar.lc = 2*PREFETCH_DIST - 1
shr.u cnt=in2,7 // number of lines
add src1 = 3*8, src_pre_mem // first t3 src
add dst0 = 8, dst_pre_mem // first t1 dst
add dst1 = 3*8, dst_pre_mem // first t3 dst
;;
and tmp=127,in2 // remaining bytes after this block
add cnt = -(2*PREFETCH_DIST) - 1, cnt
// same as .line_copy loop, but with all predicated-off instructions removed:
.prefetch_loop:
EX(.ex_hndlr_lcpy_1, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0
EK(.ex_hndlr_lcpy_1, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2
br.ctop.sptk .prefetch_loop
;;
cmp.eq p16, p0 = r0, r0 // reset p16 to 1
mov ar.lc = cnt
mov ar.ec = N // # of stages in pipeline
;;
.line_copy:
EX(.ex_handler, (p[D]) ld8 t2 = [src0], 3*8) // M0
EK(.ex_handler, (p[D]) ld8 t4 = [src1], 3*8) // M1
EX(.ex_handler_lcpy, (p[B]) st8 [dst_pre_mem] = v[B], 128) // M2 prefetch dst from memory
EK(.ex_handler_lcpy, (p[D]) st8 [dst_pre_l2] = n8, 128) // M3 prefetch dst from L2
;;
EX(.ex_handler_lcpy, (p[A]) ld8 v[A] = [src_pre_mem], 128) // M0 prefetch src from memory
EK(.ex_handler_lcpy, (p[C]) ld8 n8 = [src_pre_l2], 128) // M1 prefetch src from L2
EX(.ex_handler, (p[D]) st8 [dst0] = t1, 8) // M2
EK(.ex_handler, (p[D]) st8 [dst1] = t3, 8) // M3
;;
EX(.ex_handler, (p[D]) ld8 t5 = [src0], 8)
EK(.ex_handler, (p[D]) ld8 t7 = [src1], 3*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t2, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t4, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t6 = [src0], 3*8)
EK(.ex_handler, (p[D]) ld8 t10 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t5, 8)
EK(.ex_handler, (p[D]) st8 [dst1] = t7, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t9 = [src0], 3*8)
EK(.ex_handler, (p[D]) ld8 t11 = [src1], 3*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t6, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t10, 8)
;;
EX(.ex_handler, (p[D]) ld8 t12 = [src0], 8)
EK(.ex_handler, (p[D]) ld8 t14 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t9, 3*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t11, 3*8)
;;
EX(.ex_handler, (p[D]) ld8 t13 = [src0], 4*8)
EK(.ex_handler, (p[D]) ld8 t15 = [src1], 4*8)
EX(.ex_handler, (p[D]) st8 [dst0] = t12, 8)
EK(.ex_handler, (p[D]) st8 [dst1] = t14, 8)
;;
EX(.ex_handler, (p[C]) ld8 t1 = [src0], 8)
EK(.ex_handler, (p[C]) ld8 t3 = [src1], 8)
EX(.ex_handler, (p[D]) st8 [dst0] = t13, 4*8)
EK(.ex_handler, (p[D]) st8 [dst1] = t15, 4*8)
br.ctop.sptk .line_copy
;;
add dst0=-8,dst0
add src0=-8,src0
mov in2=tmp
.restore sp
br.sptk.many .medium_copy
;;
#define BLOCK_SIZE 128*32
#define blocksize r23
#define curlen r24
// dest is on 8-byte boundary, src is not. We need to do
// ld8-ld8, shrp, then st8. Max 8 byte copy per cycle.
.unaligned_src:
.prologue
.save ar.pfs, saved_pfs
alloc saved_pfs=ar.pfs,3,5,0,8
.save ar.lc, saved_lc
mov saved_lc=ar.lc
.save pr, saved_pr
mov saved_pr=pr
.body
.4k_block:
mov saved_in0=dst0 // need to save all input arguments
mov saved_in2=in2
mov blocksize=BLOCK_SIZE
;;
cmp.lt p6,p7=blocksize,in2
mov saved_in1=src0
;;
(p6) mov in2=blocksize
;;
shr.u r21=in2,7 // this much cache line
shr.u r22=in2,4 // number of 16-byte iteration
and curlen=15,in2 // copy length after iteration
and r30=7,src0 // source alignment
;;
cmp.lt p7,p8=1,r21
add cnt=-1,r21
;;
add src_pre_mem=0,src0 // prefetch src pointer
add dst_pre_mem=0,dst0 // prefetch dest pointer
and src0=-8,src0 // 1st src pointer
(p7) mov ar.lc = cnt
(p8) mov ar.lc = r0
;;
TEXT_ALIGN(32)
1: lfetch.fault [src_pre_mem], 128
lfetch.fault.excl [dst_pre_mem], 128
br.cloop.dptk.few 1b
;;
shladd dst1=r22,3,dst0 // 2nd dest pointer
shladd src1=r22,3,src0 // 2nd src pointer
cmp.eq p8,p9=r22,r0 // do we really need to loop?
cmp.le p6,p7=8,curlen; // have at least 8 byte remaining?
add cnt=-1,r22 // ctop iteration adjustment
;;
EX(.ex_handler, (p9) ld8 r33=[src0],8) // loop primer
EK(.ex_handler, (p9) ld8 r37=[src1],8)
(p8) br.dpnt.few .noloop
;;
// The jump address is calculated based on src alignment. The COPYU
// macro below need to confine its size to power of two, so an entry
// can be caulated using shl instead of an expensive multiply. The
// size is then hard coded by the following #define to match the
// actual size. This make it somewhat tedious when COPYU macro gets
// changed and this need to be adjusted to match.
#define LOOP_SIZE 6
1:
mov r29=ip // jmp_table thread
mov ar.lc=cnt
;;
add r29=.jump_table - 1b - (.jmp1-.jump_table), r29
shl r28=r30, LOOP_SIZE // jmp_table thread
mov ar.ec=2 // loop setup
;;
add r29=r29,r28 // jmp_table thread
cmp.eq p16,p17=r0,r0
;;
mov b6=r29 // jmp_table thread
;;
br.cond.sptk.few b6
// for 8-15 byte case
// We will skip the loop, but need to replicate the side effect
// that the loop produces.
.noloop:
EX(.ex_handler, (p6) ld8 r37=[src1],8)
add src0=8,src0
(p6) shl r25=r30,3
;;
EX(.ex_handler, (p6) ld8 r27=[src1])
(p6) shr.u r28=r37,r25
(p6) sub r26=64,r25
;;
(p6) shl r27=r27,r26
;;
(p6) or r21=r28,r27
.unaligned_src_tail:
/* check if we have more than blocksize to copy, if so go back */
cmp.gt p8,p0=saved_in2,blocksize
;;
(p8) add dst0=saved_in0,blocksize
(p8) add src0=saved_in1,blocksize
(p8) sub in2=saved_in2,blocksize
(p8) br.dpnt .4k_block
;;
/* we have up to 15 byte to copy in the tail.
* part of work is already done in the jump table code
* we are at the following state.
* src side:
*
* xxxxxx xx <----- r21 has xxxxxxxx already
* -------- -------- --------
* 0 8 16
* ^
* |
* src1
*
* dst
* -------- -------- --------
* ^
* |
* dst1
*/
EX(.ex_handler, (p6) st8 [dst1]=r21,8) // more than 8 byte to copy
(p6) add curlen=-8,curlen // update length
mov ar.pfs=saved_pfs
;;
mov ar.lc=saved_lc
mov pr=saved_pr,-1
mov in2=curlen // remaining length
mov dst0=dst1 // dest pointer
add src0=src1,r30 // forward by src alignment
;;
// 7 byte or smaller.
.memcpy_short:
cmp.le p8,p9 = 1,in2
cmp.le p10,p11 = 2,in2
cmp.le p12,p13 = 3,in2
cmp.le p14,p15 = 4,in2
add src1=1,src0 // second src pointer
add dst1=1,dst0 // second dest pointer
;;
EX(.ex_handler_short, (p8) ld1 t1=[src0],2)
EK(.ex_handler_short, (p10) ld1 t2=[src1],2)
(p9) br.ret.dpnt rp // 0 byte copy
;;
EX(.ex_handler_short, (p8) st1 [dst0]=t1,2)
EK(.ex_handler_short, (p10) st1 [dst1]=t2,2)
(p11) br.ret.dpnt rp // 1 byte copy
EX(.ex_handler_short, (p12) ld1 t3=[src0],2)
EK(.ex_handler_short, (p14) ld1 t4=[src1],2)
(p13) br.ret.dpnt rp // 2 byte copy
;;
cmp.le p6,p7 = 5,in2
cmp.le p8,p9 = 6,in2
cmp.le p10,p11 = 7,in2
EX(.ex_handler_short, (p12) st1 [dst0]=t3,2)
EK(.ex_handler_short, (p14) st1 [dst1]=t4,2)
(p15) br.ret.dpnt rp // 3 byte copy
;;
EX(.ex_handler_short, (p6) ld1 t5=[src0],2)
EK(.ex_handler_short, (p8) ld1 t6=[src1],2)
(p7) br.ret.dpnt rp // 4 byte copy
;;
EX(.ex_handler_short, (p6) st1 [dst0]=t5,2)
EK(.ex_handler_short, (p8) st1 [dst1]=t6,2)
(p9) br.ret.dptk rp // 5 byte copy
EX(.ex_handler_short, (p10) ld1 t7=[src0],2)
(p11) br.ret.dptk rp // 6 byte copy
;;
EX(.ex_handler_short, (p10) st1 [dst0]=t7,2)
br.ret.dptk rp // done all cases
/* Align dest to nearest 8-byte boundary. We know we have at
* least 7 bytes to copy, enough to crawl to 8-byte boundary.
* Actual number of byte to crawl depend on the dest alignment.
* 7 byte or less is taken care at .memcpy_short
* src0 - source even index
* src1 - source odd index
* dst0 - dest even index
* dst1 - dest odd index
* r30 - distance to 8-byte boundary
*/
.align_dest:
add src1=1,in1 // source odd index
cmp.le p7,p0 = 2,r30 // for .align_dest
cmp.le p8,p0 = 3,r30 // for .align_dest
EX(.ex_handler_short, (p6) ld1 t1=[src0],2)
cmp.le p9,p0 = 4,r30 // for .align_dest
cmp.le p10,p0 = 5,r30
;;
EX(.ex_handler_short, (p7) ld1 t2=[src1],2)
EK(.ex_handler_short, (p8) ld1 t3=[src0],2)
cmp.le p11,p0 = 6,r30
EX(.ex_handler_short, (p6) st1 [dst0] = t1,2)
cmp.le p12,p0 = 7,r30
;;
EX(.ex_handler_short, (p9) ld1 t4=[src1],2)
EK(.ex_handler_short, (p10) ld1 t5=[src0],2)
EX(.ex_handler_short, (p7) st1 [dst1] = t2,2)
EK(.ex_handler_short, (p8) st1 [dst0] = t3,2)
;;
EX(.ex_handler_short, (p11) ld1 t6=[src1],2)
EK(.ex_handler_short, (p12) ld1 t7=[src0],2)
cmp.eq p6,p7=r28,r29
EX(.ex_handler_short, (p9) st1 [dst1] = t4,2)
EK(.ex_handler_short, (p10) st1 [dst0] = t5,2)
sub in2=in2,r30
;;
EX(.ex_handler_short, (p11) st1 [dst1] = t6,2)
EK(.ex_handler_short, (p12) st1 [dst0] = t7)
add dst0=in0,r30 // setup arguments
add src0=in1,r30
(p6) br.cond.dptk .aligned_src
(p7) br.cond.dpnt .unaligned_src
;;
/* main loop body in jump table format */
#define COPYU(shift) \
1: \
EX(.ex_handler, (p16) ld8 r32=[src0],8); /* 1 */ \
EK(.ex_handler, (p16) ld8 r36=[src1],8); \
(p17) shrp r35=r33,r34,shift;; /* 1 */ \
EX(.ex_handler, (p6) ld8 r22=[src1]); /* common, prime for tail section */ \
nop.m 0; \
(p16) shrp r38=r36,r37,shift; \
EX(.ex_handler, (p17) st8 [dst0]=r35,8); /* 1 */ \
EK(.ex_handler, (p17) st8 [dst1]=r39,8); \
br.ctop.dptk.few 1b;; \
(p7) add src1=-8,src1; /* back out for <8 byte case */ \
shrp r21=r22,r38,shift; /* speculative work */ \
br.sptk.few .unaligned_src_tail /* branch out of jump table */ \
;;
TEXT_ALIGN(32)
.jump_table:
COPYU(8) // unaligned cases
.jmp1:
COPYU(16)
COPYU(24)
COPYU(32)
COPYU(40)
COPYU(48)
COPYU(56)
#undef A
#undef B
#undef C
#undef D
/*
* Due to lack of local tag support in gcc 2.x assembler, it is not clear which
* instruction failed in the bundle. The exception algorithm is that we
* first figure out the faulting address, then detect if there is any
* progress made on the copy, if so, redo the copy from last known copied
* location up to the faulting address (exclusive). In the copy_from_user
* case, remaining byte in kernel buffer will be zeroed.
*
* Take copy_from_user as an example, in the code there are multiple loads
* in a bundle and those multiple loads could span over two pages, the
* faulting address is calculated as page_round_down(max(src0, src1)).
* This is based on knowledge that if we can access one byte in a page, we
* can access any byte in that page.
*
* predicate used in the exception handler:
* p6-p7: direction
* p10-p11: src faulting addr calculation
* p12-p13: dst faulting addr calculation
*/
#define A r19
#define B r20
#define C r21
#define D r22
#define F r28
#define saved_retval loc0
#define saved_rtlink loc1
#define saved_pfs_stack loc2
.ex_hndlr_s:
add src0=8,src0
br.sptk .ex_handler
;;
.ex_hndlr_d:
add dst0=8,dst0
br.sptk .ex_handler
;;
.ex_hndlr_lcpy_1:
mov src1=src_pre_mem
mov dst1=dst_pre_mem
cmp.gtu p10,p11=src_pre_mem,saved_in1
cmp.gtu p12,p13=dst_pre_mem,saved_in0
;;
(p10) add src0=8,saved_in1
(p11) mov src0=saved_in1
(p12) add dst0=8,saved_in0
(p13) mov dst0=saved_in0
br.sptk .ex_handler
.ex_handler_lcpy:
// in line_copy block, the preload addresses should always ahead
// of the other two src/dst pointers. Furthermore, src1/dst1 should
// always ahead of src0/dst0.
mov src1=src_pre_mem
mov dst1=dst_pre_mem
.ex_handler:
mov pr=saved_pr,-1 // first restore pr, lc, and pfs
mov ar.lc=saved_lc
mov ar.pfs=saved_pfs
;;
.ex_handler_short: // fault occurred in these sections didn't change pr, lc, pfs
cmp.ltu p6,p7=saved_in0, saved_in1 // get the copy direction
cmp.ltu p10,p11=src0,src1
cmp.ltu p12,p13=dst0,dst1
fcmp.eq p8,p0=f6,f0 // is it memcpy?
mov tmp = dst0
;;
(p11) mov src1 = src0 // pick the larger of the two
(p13) mov dst0 = dst1 // make dst0 the smaller one
(p13) mov dst1 = tmp // and dst1 the larger one
;;
(p6) dep F = r0,dst1,0,PAGE_SHIFT // usr dst round down to page boundary
(p7) dep F = r0,src1,0,PAGE_SHIFT // usr src round down to page boundary
;;
(p6) cmp.le p14,p0=dst0,saved_in0 // no progress has been made on store
(p7) cmp.le p14,p0=src0,saved_in1 // no progress has been made on load
mov retval=saved_in2
(p8) ld1 tmp=[src1] // force an oops for memcpy call
(p8) st1 [dst1]=r0 // force an oops for memcpy call
(p14) br.ret.sptk.many rp
/*
* The remaining byte to copy is calculated as:
*
* A = (faulting_addr - orig_src) -> len to faulting ld address
* or
* (faulting_addr - orig_dst) -> len to faulting st address
* B = (cur_dst - orig_dst) -> len copied so far
* C = A - B -> len need to be copied
* D = orig_len - A -> len need to be left along
*/
(p6) sub A = F, saved_in0
(p7) sub A = F, saved_in1
clrrrb
;;
alloc saved_pfs_stack=ar.pfs,3,3,3,0
cmp.lt p8,p0=A,r0
sub B = dst0, saved_in0 // how many byte copied so far
;;
(p8) mov A = 0; // A shouldn't be negative, cap it
;;
sub C = A, B
sub D = saved_in2, A
;;
cmp.gt p8,p0=C,r0 // more than 1 byte?
mov r8=0
mov saved_retval = D
mov saved_rtlink = b0
add out0=saved_in0, B
add out1=saved_in1, B
mov out2=C
(p8) br.call.sptk.few b0=__copy_user // recursive call
;;
add saved_retval=saved_retval,r8 // above might return non-zero value
;;
mov retval=saved_retval
mov ar.pfs=saved_pfs_stack
mov b0=saved_rtlink
br.ret.sptk.many rp
/* end of McKinley specific optimization */
END(__copy_user)
EXPORT_SYMBOL(__copy_user)
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