/* * 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> #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) 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 memset_arg0 r32 #define memset_arg2 r33 #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 zeroed */ (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? add memset_arg0=saved_in0, A (p6) mov memset_arg2=0 // copy_to_user should not call memset (p7) mov memset_arg2=D // copy_from_user need to have kbuf zeroed 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 cmp.gt p8,p0=memset_arg2,r0 // more than 1 byte? mov out0=memset_arg0 // *s mov out1=r0 // c mov out2=memset_arg2 // n (p8) br.call.sptk.few b0=memset ;; 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)