From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- arch/alpha/lib/ev6-copy_user.S | 227 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 227 insertions(+) create mode 100644 arch/alpha/lib/ev6-copy_user.S (limited to 'arch/alpha/lib/ev6-copy_user.S') diff --git a/arch/alpha/lib/ev6-copy_user.S b/arch/alpha/lib/ev6-copy_user.S new file mode 100644 index 0000000000..b9b19710c3 --- /dev/null +++ b/arch/alpha/lib/ev6-copy_user.S @@ -0,0 +1,227 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * arch/alpha/lib/ev6-copy_user.S + * + * 21264 version contributed by Rick Gorton + * + * Copy to/from user space, handling exceptions as we go.. This + * isn't exactly pretty. + * + * This is essentially the same as "memcpy()", but with a few twists. + * Notably, we have to make sure that $0 is always up-to-date and + * contains the right "bytes left to copy" value (and that it is updated + * only _after_ a successful copy). There is also some rather minor + * exception setup stuff.. + * + * Much of the information about 21264 scheduling/coding comes from: + * Compiler Writer's Guide for the Alpha 21264 + * abbreviated as 'CWG' in other comments here + * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html + * Scheduling notation: + * E - either cluster + * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 + * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 + */ + +#include +/* Allow an exception for an insn; exit if we get one. */ +#define EXI(x,y...) \ + 99: x,##y; \ + .section __ex_table,"a"; \ + .long 99b - .; \ + lda $31, $exitin-99b($31); \ + .previous + +#define EXO(x,y...) \ + 99: x,##y; \ + .section __ex_table,"a"; \ + .long 99b - .; \ + lda $31, $exitout-99b($31); \ + .previous + + .set noat + .align 4 + .globl __copy_user + .ent __copy_user + # Pipeline info: Slotting & Comments +__copy_user: + .prologue 0 + mov $18, $0 # .. .. .. E + subq $18, 32, $1 # .. .. E. .. : Is this going to be a small copy? + nop # .. E .. .. + beq $18, $zerolength # U .. .. .. : U L U L + + and $16,7,$3 # .. .. .. E : is leading dest misalignment + ble $1, $onebyteloop # .. .. U .. : 1st branch : small amount of data + beq $3, $destaligned # .. U .. .. : 2nd (one cycle fetcher stall) + subq $3, 8, $3 # E .. .. .. : L U U L : trip counter +/* + * The fetcher stall also hides the 1 cycle cross-cluster stall for $3 (L --> U) + * This loop aligns the destination a byte at a time + * We know we have at least one trip through this loop + */ +$aligndest: + EXI( ldbu $1,0($17) ) # .. .. .. L : Keep loads separate from stores + addq $16,1,$16 # .. .. E .. : Section 3.8 in the CWG + addq $3,1,$3 # .. E .. .. : + nop # E .. .. .. : U L U L + +/* + * the -1 is to compensate for the inc($16) done in a previous quadpack + * which allows us zero dependencies within either quadpack in the loop + */ + EXO( stb $1,-1($16) ) # .. .. .. L : + addq $17,1,$17 # .. .. E .. : Section 3.8 in the CWG + subq $0,1,$0 # .. E .. .. : + bne $3, $aligndest # U .. .. .. : U L U L + +/* + * If we fell through into here, we have a minimum of 33 - 7 bytes + * If we arrived via branch, we have a minimum of 32 bytes + */ +$destaligned: + and $17,7,$1 # .. .. .. E : Check _current_ source alignment + bic $0,7,$4 # .. .. E .. : number bytes as a quadword loop + EXI( ldq_u $3,0($17) ) # .. L .. .. : Forward fetch for fallthrough code + beq $1,$quadaligned # U .. .. .. : U L U L + +/* + * In the worst case, we've just executed an ldq_u here from 0($17) + * and we'll repeat it once if we take the branch + */ + +/* Misaligned quadword loop - not unrolled. Leave it that way. */ +$misquad: + EXI( ldq_u $2,8($17) ) # .. .. .. L : + subq $4,8,$4 # .. .. E .. : + extql $3,$17,$3 # .. U .. .. : + extqh $2,$17,$1 # U .. .. .. : U U L L + + bis $3,$1,$1 # .. .. .. E : + EXO( stq $1,0($16) ) # .. .. L .. : + addq $17,8,$17 # .. E .. .. : + subq $0,8,$0 # E .. .. .. : U L L U + + addq $16,8,$16 # .. .. .. E : + bis $2,$2,$3 # .. .. E .. : + nop # .. E .. .. : + bne $4,$misquad # U .. .. .. : U L U L + + nop # .. .. .. E + nop # .. .. E .. + nop # .. E .. .. + beq $0,$zerolength # U .. .. .. : U L U L + +/* We know we have at least one trip through the byte loop */ + EXI ( ldbu $2,0($17) ) # .. .. .. L : No loads in the same quad + addq $16,1,$16 # .. .. E .. : as the store (Section 3.8 in CWG) + nop # .. E .. .. : + br $31, $dirtyentry # L0 .. .. .. : L U U L +/* Do the trailing byte loop load, then hop into the store part of the loop */ + +/* + * A minimum of (33 - 7) bytes to do a quad at a time. + * Based upon the usage context, it's worth the effort to unroll this loop + * $0 - number of bytes to be moved + * $4 - number of bytes to move as quadwords + * $16 is current destination address + * $17 is current source address + */ +$quadaligned: + subq $4, 32, $2 # .. .. .. E : do not unroll for small stuff + nop # .. .. E .. + nop # .. E .. .. + blt $2, $onequad # U .. .. .. : U L U L + +/* + * There is a significant assumption here that the source and destination + * addresses differ by more than 32 bytes. In this particular case, a + * sparsity of registers further bounds this to be a minimum of 8 bytes. + * But if this isn't met, then the output result will be incorrect. + * Furthermore, due to a lack of available registers, we really can't + * unroll this to be an 8x loop (which would enable us to use the wh64 + * instruction memory hint instruction). + */ +$unroll4: + EXI( ldq $1,0($17) ) # .. .. .. L + EXI( ldq $2,8($17) ) # .. .. L .. + subq $4,32,$4 # .. E .. .. + nop # E .. .. .. : U U L L + + addq $17,16,$17 # .. .. .. E + EXO( stq $1,0($16) ) # .. .. L .. + EXO( stq $2,8($16) ) # .. L .. .. + subq $0,16,$0 # E .. .. .. : U L L U + + addq $16,16,$16 # .. .. .. E + EXI( ldq $1,0($17) ) # .. .. L .. + EXI( ldq $2,8($17) ) # .. L .. .. + subq $4, 32, $3 # E .. .. .. : U U L L : is there enough for another trip? + + EXO( stq $1,0($16) ) # .. .. .. L + EXO( stq $2,8($16) ) # .. .. L .. + subq $0,16,$0 # .. E .. .. + addq $17,16,$17 # E .. .. .. : U L L U + + nop # .. .. .. E + nop # .. .. E .. + addq $16,16,$16 # .. E .. .. + bgt $3,$unroll4 # U .. .. .. : U L U L + + nop + nop + nop + beq $4, $noquads + +$onequad: + EXI( ldq $1,0($17) ) + subq $4,8,$4 + addq $17,8,$17 + nop + + EXO( stq $1,0($16) ) + subq $0,8,$0 + addq $16,8,$16 + bne $4,$onequad + +$noquads: + nop + nop + nop + beq $0,$zerolength + +/* + * For small copies (or the tail of a larger copy), do a very simple byte loop. + * There's no point in doing a lot of complex alignment calculations to try to + * to quadword stuff for a small amount of data. + * $0 - remaining number of bytes left to copy + * $16 - current dest addr + * $17 - current source addr + */ + +$onebyteloop: + EXI ( ldbu $2,0($17) ) # .. .. .. L : No loads in the same quad + addq $16,1,$16 # .. .. E .. : as the store (Section 3.8 in CWG) + nop # .. E .. .. : + nop # E .. .. .. : U L U L + +$dirtyentry: +/* + * the -1 is to compensate for the inc($16) done in a previous quadpack + * which allows us zero dependencies within either quadpack in the loop + */ + EXO ( stb $2,-1($16) ) # .. .. .. L : + addq $17,1,$17 # .. .. E .. : quadpack as the load + subq $0,1,$0 # .. E .. .. : change count _after_ copy + bgt $0,$onebyteloop # U .. .. .. : U L U L + +$zerolength: +$exitin: +$exitout: # Destination for exception recovery(?) + nop # .. .. .. E + nop # .. .. E .. + nop # .. E .. .. + ret $31,($26),1 # L0 .. .. .. : L U L U + + .end __copy_user + EXPORT_SYMBOL(__copy_user) -- cgit v1.2.3