1b2441318SGreg Kroah-Hartman/* SPDX-License-Identifier: GPL-2.0 */ 21da177e4SLinus Torvalds/* 31da177e4SLinus Torvalds * arch/alpha/lib/ev6-copy_user.S 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com> 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Copy to/from user space, handling exceptions as we go.. This 81da177e4SLinus Torvalds * isn't exactly pretty. 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * This is essentially the same as "memcpy()", but with a few twists. 111da177e4SLinus Torvalds * Notably, we have to make sure that $0 is always up-to-date and 121da177e4SLinus Torvalds * contains the right "bytes left to copy" value (and that it is updated 131da177e4SLinus Torvalds * only _after_ a successful copy). There is also some rather minor 141da177e4SLinus Torvalds * exception setup stuff.. 151da177e4SLinus Torvalds * 161da177e4SLinus Torvalds * Much of the information about 21264 scheduling/coding comes from: 171da177e4SLinus Torvalds * Compiler Writer's Guide for the Alpha 21264 181da177e4SLinus Torvalds * abbreviated as 'CWG' in other comments here 191da177e4SLinus Torvalds * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html 201da177e4SLinus Torvalds * Scheduling notation: 211da177e4SLinus Torvalds * E - either cluster 221da177e4SLinus Torvalds * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 231da177e4SLinus Torvalds * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 241da177e4SLinus Torvalds */ 251da177e4SLinus Torvalds 26*f3c78e94SMasahiro Yamada#include <linux/export.h> 271da177e4SLinus Torvalds/* Allow an exception for an insn; exit if we get one. */ 281da177e4SLinus Torvalds#define EXI(x,y...) \ 291da177e4SLinus Torvalds 99: x,##y; \ 301da177e4SLinus Torvalds .section __ex_table,"a"; \ 311da177e4SLinus Torvalds .long 99b - .; \ 321da177e4SLinus Torvalds lda $31, $exitin-99b($31); \ 331da177e4SLinus Torvalds .previous 341da177e4SLinus Torvalds 351da177e4SLinus Torvalds#define EXO(x,y...) \ 361da177e4SLinus Torvalds 99: x,##y; \ 371da177e4SLinus Torvalds .section __ex_table,"a"; \ 381da177e4SLinus Torvalds .long 99b - .; \ 391da177e4SLinus Torvalds lda $31, $exitout-99b($31); \ 401da177e4SLinus Torvalds .previous 411da177e4SLinus Torvalds 421da177e4SLinus Torvalds .set noat 431da177e4SLinus Torvalds .align 4 441da177e4SLinus Torvalds .globl __copy_user 451da177e4SLinus Torvalds .ent __copy_user 461da177e4SLinus Torvalds # Pipeline info: Slotting & Comments 471da177e4SLinus Torvalds__copy_user: 481da177e4SLinus Torvalds .prologue 0 494606f68fSRichard Henderson mov $18, $0 # .. .. .. E 504606f68fSRichard Henderson subq $18, 32, $1 # .. .. E. .. : Is this going to be a small copy? 514606f68fSRichard Henderson nop # .. E .. .. 524606f68fSRichard Henderson beq $18, $zerolength # U .. .. .. : U L U L 531da177e4SLinus Torvalds 5485250231SAl Viro and $16,7,$3 # .. .. .. E : is leading dest misalignment 551da177e4SLinus Torvalds ble $1, $onebyteloop # .. .. U .. : 1st branch : small amount of data 561da177e4SLinus Torvalds beq $3, $destaligned # .. U .. .. : 2nd (one cycle fetcher stall) 571da177e4SLinus Torvalds subq $3, 8, $3 # E .. .. .. : L U U L : trip counter 581da177e4SLinus Torvalds/* 591da177e4SLinus Torvalds * The fetcher stall also hides the 1 cycle cross-cluster stall for $3 (L --> U) 601da177e4SLinus Torvalds * This loop aligns the destination a byte at a time 611da177e4SLinus Torvalds * We know we have at least one trip through this loop 621da177e4SLinus Torvalds */ 631da177e4SLinus Torvalds$aligndest: 6485250231SAl Viro EXI( ldbu $1,0($17) ) # .. .. .. L : Keep loads separate from stores 6585250231SAl Viro addq $16,1,$16 # .. .. E .. : Section 3.8 in the CWG 661da177e4SLinus Torvalds addq $3,1,$3 # .. E .. .. : 671da177e4SLinus Torvalds nop # E .. .. .. : U L U L 681da177e4SLinus Torvalds 691da177e4SLinus Torvalds/* 7085250231SAl Viro * the -1 is to compensate for the inc($16) done in a previous quadpack 711da177e4SLinus Torvalds * which allows us zero dependencies within either quadpack in the loop 721da177e4SLinus Torvalds */ 7385250231SAl Viro EXO( stb $1,-1($16) ) # .. .. .. L : 7485250231SAl Viro addq $17,1,$17 # .. .. E .. : Section 3.8 in the CWG 751da177e4SLinus Torvalds subq $0,1,$0 # .. E .. .. : 761da177e4SLinus Torvalds bne $3, $aligndest # U .. .. .. : U L U L 771da177e4SLinus Torvalds 781da177e4SLinus Torvalds/* 791da177e4SLinus Torvalds * If we fell through into here, we have a minimum of 33 - 7 bytes 801da177e4SLinus Torvalds * If we arrived via branch, we have a minimum of 32 bytes 811da177e4SLinus Torvalds */ 821da177e4SLinus Torvalds$destaligned: 8385250231SAl Viro and $17,7,$1 # .. .. .. E : Check _current_ source alignment 841da177e4SLinus Torvalds bic $0,7,$4 # .. .. E .. : number bytes as a quadword loop 8585250231SAl Viro EXI( ldq_u $3,0($17) ) # .. L .. .. : Forward fetch for fallthrough code 861da177e4SLinus Torvalds beq $1,$quadaligned # U .. .. .. : U L U L 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds/* 8985250231SAl Viro * In the worst case, we've just executed an ldq_u here from 0($17) 901da177e4SLinus Torvalds * and we'll repeat it once if we take the branch 911da177e4SLinus Torvalds */ 921da177e4SLinus Torvalds 931da177e4SLinus Torvalds/* Misaligned quadword loop - not unrolled. Leave it that way. */ 941da177e4SLinus Torvalds$misquad: 9585250231SAl Viro EXI( ldq_u $2,8($17) ) # .. .. .. L : 961da177e4SLinus Torvalds subq $4,8,$4 # .. .. E .. : 9785250231SAl Viro extql $3,$17,$3 # .. U .. .. : 9885250231SAl Viro extqh $2,$17,$1 # U .. .. .. : U U L L 991da177e4SLinus Torvalds 1001da177e4SLinus Torvalds bis $3,$1,$1 # .. .. .. E : 10185250231SAl Viro EXO( stq $1,0($16) ) # .. .. L .. : 10285250231SAl Viro addq $17,8,$17 # .. E .. .. : 1031da177e4SLinus Torvalds subq $0,8,$0 # E .. .. .. : U L L U 1041da177e4SLinus Torvalds 10585250231SAl Viro addq $16,8,$16 # .. .. .. E : 1061da177e4SLinus Torvalds bis $2,$2,$3 # .. .. E .. : 1071da177e4SLinus Torvalds nop # .. E .. .. : 1081da177e4SLinus Torvalds bne $4,$misquad # U .. .. .. : U L U L 1091da177e4SLinus Torvalds 1101da177e4SLinus Torvalds nop # .. .. .. E 1111da177e4SLinus Torvalds nop # .. .. E .. 1121da177e4SLinus Torvalds nop # .. E .. .. 1131da177e4SLinus Torvalds beq $0,$zerolength # U .. .. .. : U L U L 1141da177e4SLinus Torvalds 1151da177e4SLinus Torvalds/* We know we have at least one trip through the byte loop */ 11685250231SAl Viro EXI ( ldbu $2,0($17) ) # .. .. .. L : No loads in the same quad 11785250231SAl Viro addq $16,1,$16 # .. .. E .. : as the store (Section 3.8 in CWG) 1181da177e4SLinus Torvalds nop # .. E .. .. : 1191da177e4SLinus Torvalds br $31, $dirtyentry # L0 .. .. .. : L U U L 1201da177e4SLinus Torvalds/* Do the trailing byte loop load, then hop into the store part of the loop */ 1211da177e4SLinus Torvalds 1221da177e4SLinus Torvalds/* 1231da177e4SLinus Torvalds * A minimum of (33 - 7) bytes to do a quad at a time. 1241da177e4SLinus Torvalds * Based upon the usage context, it's worth the effort to unroll this loop 1251da177e4SLinus Torvalds * $0 - number of bytes to be moved 1261da177e4SLinus Torvalds * $4 - number of bytes to move as quadwords 12785250231SAl Viro * $16 is current destination address 12885250231SAl Viro * $17 is current source address 1291da177e4SLinus Torvalds */ 1301da177e4SLinus Torvalds$quadaligned: 1311da177e4SLinus Torvalds subq $4, 32, $2 # .. .. .. E : do not unroll for small stuff 1321da177e4SLinus Torvalds nop # .. .. E .. 1331da177e4SLinus Torvalds nop # .. E .. .. 1341da177e4SLinus Torvalds blt $2, $onequad # U .. .. .. : U L U L 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds/* 1371da177e4SLinus Torvalds * There is a significant assumption here that the source and destination 1381da177e4SLinus Torvalds * addresses differ by more than 32 bytes. In this particular case, a 1391da177e4SLinus Torvalds * sparsity of registers further bounds this to be a minimum of 8 bytes. 1401da177e4SLinus Torvalds * But if this isn't met, then the output result will be incorrect. 1411da177e4SLinus Torvalds * Furthermore, due to a lack of available registers, we really can't 1421da177e4SLinus Torvalds * unroll this to be an 8x loop (which would enable us to use the wh64 1431da177e4SLinus Torvalds * instruction memory hint instruction). 1441da177e4SLinus Torvalds */ 1451da177e4SLinus Torvalds$unroll4: 14685250231SAl Viro EXI( ldq $1,0($17) ) # .. .. .. L 14785250231SAl Viro EXI( ldq $2,8($17) ) # .. .. L .. 1481da177e4SLinus Torvalds subq $4,32,$4 # .. E .. .. 1491da177e4SLinus Torvalds nop # E .. .. .. : U U L L 1501da177e4SLinus Torvalds 15185250231SAl Viro addq $17,16,$17 # .. .. .. E 15285250231SAl Viro EXO( stq $1,0($16) ) # .. .. L .. 15385250231SAl Viro EXO( stq $2,8($16) ) # .. L .. .. 1541da177e4SLinus Torvalds subq $0,16,$0 # E .. .. .. : U L L U 1551da177e4SLinus Torvalds 15685250231SAl Viro addq $16,16,$16 # .. .. .. E 15785250231SAl Viro EXI( ldq $1,0($17) ) # .. .. L .. 15885250231SAl Viro EXI( ldq $2,8($17) ) # .. L .. .. 1591da177e4SLinus Torvalds subq $4, 32, $3 # E .. .. .. : U U L L : is there enough for another trip? 1601da177e4SLinus Torvalds 16185250231SAl Viro EXO( stq $1,0($16) ) # .. .. .. L 16285250231SAl Viro EXO( stq $2,8($16) ) # .. .. L .. 1631da177e4SLinus Torvalds subq $0,16,$0 # .. E .. .. 16485250231SAl Viro addq $17,16,$17 # E .. .. .. : U L L U 1651da177e4SLinus Torvalds 1661da177e4SLinus Torvalds nop # .. .. .. E 1671da177e4SLinus Torvalds nop # .. .. E .. 16885250231SAl Viro addq $16,16,$16 # .. E .. .. 1691da177e4SLinus Torvalds bgt $3,$unroll4 # U .. .. .. : U L U L 1701da177e4SLinus Torvalds 1711da177e4SLinus Torvalds nop 1721da177e4SLinus Torvalds nop 1731da177e4SLinus Torvalds nop 1741da177e4SLinus Torvalds beq $4, $noquads 1751da177e4SLinus Torvalds 1761da177e4SLinus Torvalds$onequad: 17785250231SAl Viro EXI( ldq $1,0($17) ) 1781da177e4SLinus Torvalds subq $4,8,$4 17985250231SAl Viro addq $17,8,$17 1801da177e4SLinus Torvalds nop 1811da177e4SLinus Torvalds 18285250231SAl Viro EXO( stq $1,0($16) ) 1831da177e4SLinus Torvalds subq $0,8,$0 18485250231SAl Viro addq $16,8,$16 1851da177e4SLinus Torvalds bne $4,$onequad 1861da177e4SLinus Torvalds 1871da177e4SLinus Torvalds$noquads: 1881da177e4SLinus Torvalds nop 1891da177e4SLinus Torvalds nop 1901da177e4SLinus Torvalds nop 1911da177e4SLinus Torvalds beq $0,$zerolength 1921da177e4SLinus Torvalds 1931da177e4SLinus Torvalds/* 1941da177e4SLinus Torvalds * For small copies (or the tail of a larger copy), do a very simple byte loop. 1951da177e4SLinus Torvalds * There's no point in doing a lot of complex alignment calculations to try to 1961da177e4SLinus Torvalds * to quadword stuff for a small amount of data. 1971da177e4SLinus Torvalds * $0 - remaining number of bytes left to copy 19885250231SAl Viro * $16 - current dest addr 19985250231SAl Viro * $17 - current source addr 2001da177e4SLinus Torvalds */ 2011da177e4SLinus Torvalds 2021da177e4SLinus Torvalds$onebyteloop: 20385250231SAl Viro EXI ( ldbu $2,0($17) ) # .. .. .. L : No loads in the same quad 20485250231SAl Viro addq $16,1,$16 # .. .. E .. : as the store (Section 3.8 in CWG) 2051da177e4SLinus Torvalds nop # .. E .. .. : 2061da177e4SLinus Torvalds nop # E .. .. .. : U L U L 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds$dirtyentry: 2091da177e4SLinus Torvalds/* 21085250231SAl Viro * the -1 is to compensate for the inc($16) done in a previous quadpack 2111da177e4SLinus Torvalds * which allows us zero dependencies within either quadpack in the loop 2121da177e4SLinus Torvalds */ 21385250231SAl Viro EXO ( stb $2,-1($16) ) # .. .. .. L : 21485250231SAl Viro addq $17,1,$17 # .. .. E .. : quadpack as the load 2151da177e4SLinus Torvalds subq $0,1,$0 # .. E .. .. : change count _after_ copy 2161da177e4SLinus Torvalds bgt $0,$onebyteloop # U .. .. .. : U L U L 2171da177e4SLinus Torvalds 2181da177e4SLinus Torvalds$zerolength: 219085354f9SAl Viro$exitin: 2201da177e4SLinus Torvalds$exitout: # Destination for exception recovery(?) 2211da177e4SLinus Torvalds nop # .. .. .. E 2221da177e4SLinus Torvalds nop # .. .. E .. 2231da177e4SLinus Torvalds nop # .. E .. .. 22485250231SAl Viro ret $31,($26),1 # L0 .. .. .. : L U L U 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds .end __copy_user 22700fc0e0dSAl Viro EXPORT_SYMBOL(__copy_user) 228