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Diffstat (limited to 'arch/alpha/lib/ev6-strncpy_from_user.S')
| -rw-r--r-- | arch/alpha/lib/ev6-strncpy_from_user.S | 424 |
1 files changed, 0 insertions, 424 deletions
diff --git a/arch/alpha/lib/ev6-strncpy_from_user.S b/arch/alpha/lib/ev6-strncpy_from_user.S deleted file mode 100644 index d2e28178cac..00000000000 --- a/arch/alpha/lib/ev6-strncpy_from_user.S +++ /dev/null @@ -1,424 +0,0 @@ -/* - * arch/alpha/lib/ev6-strncpy_from_user.S - * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com> - * - * Just like strncpy except in the return value: - * - * -EFAULT if an exception occurs before the terminator is copied. - * N if the buffer filled. - * - * Otherwise the length of the string is returned. - * - * 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 - * A bunch of instructions got moved and temp registers were changed - * to aid in scheduling. Control flow was also re-arranged to eliminate - * branches, and to provide longer code sequences to enable better scheduling. - * A total rewrite (using byte load/stores for start & tail sequences) - * is desirable, but very difficult to do without a from-scratch rewrite. - * Save that for the future. - */ - - -#include <asm/errno.h> -#include <asm/regdef.h> - - -/* Allow an exception for an insn; exit if we get one. */ -#define EX(x,y...) \ - 99: x,##y; \ - .section __ex_table,"a"; \ - .long 99b - .; \ - lda $31, $exception-99b($0); \ - .previous - - - .set noat - .set noreorder - .text - - .globl __strncpy_from_user - .ent __strncpy_from_user - .frame $30, 0, $26 - .prologue 0 - - .align 4 -__strncpy_from_user: - and a0, 7, t3 # E : find dest misalignment - beq a2, $zerolength # U : - - /* Are source and destination co-aligned? */ - mov a0, v0 # E : save the string start - xor a0, a1, t4 # E : - EX( ldq_u t1, 0(a1) ) # L : Latency=3 load first quadword - ldq_u t0, 0(a0) # L : load first (partial) aligned dest quadword - - addq a2, t3, a2 # E : bias count by dest misalignment - subq a2, 1, a3 # E : - addq zero, 1, t10 # E : - and t4, 7, t4 # E : misalignment between the two - - and a3, 7, t6 # E : number of tail bytes - sll t10, t6, t10 # E : t10 = bitmask of last count byte - bne t4, $unaligned # U : - lda t2, -1 # E : build a mask against false zero - - /* - * We are co-aligned; take care of a partial first word. - * On entry to this basic block: - * t0 == the first destination word for masking back in - * t1 == the first source word. - */ - - srl a3, 3, a2 # E : a2 = loop counter = (count - 1)/8 - addq a1, 8, a1 # E : - mskqh t2, a1, t2 # U : detection in the src word - nop - - /* Create the 1st output word and detect 0's in the 1st input word. */ - mskqh t1, a1, t3 # U : - mskql t0, a1, t0 # U : assemble the first output word - ornot t1, t2, t2 # E : - nop - - cmpbge zero, t2, t8 # E : bits set iff null found - or t0, t3, t0 # E : - beq a2, $a_eoc # U : - bne t8, $a_eos # U : 2nd branch in a quad. Bad. - - /* On entry to this basic block: - * t0 == a source quad not containing a null. - * a0 - current aligned destination address - * a1 - current aligned source address - * a2 - count of quadwords to move. - * NOTE: Loop improvement - unrolling this is going to be - * a huge win, since we're going to stall otherwise. - * Fix this later. For _really_ large copies, look - * at using wh64 on a look-ahead basis. See the code - * in clear_user.S and copy_user.S. - * Presumably, since (a0) and (a1) do not overlap (by C definition) - * Lots of nops here: - * - Separate loads from stores - * - Keep it to 1 branch/quadpack so the branch predictor - * can train. - */ -$a_loop: - stq_u t0, 0(a0) # L : - addq a0, 8, a0 # E : - nop - subq a2, 1, a2 # E : - - EX( ldq_u t0, 0(a1) ) # L : - addq a1, 8, a1 # E : - cmpbge zero, t0, t8 # E : Stall 2 cycles on t0 - beq a2, $a_eoc # U : - - beq t8, $a_loop # U : - nop - nop - nop - - /* Take care of the final (partial) word store. At this point - * the end-of-count bit is set in t8 iff it applies. - * - * On entry to this basic block we have: - * t0 == the source word containing the null - * t8 == the cmpbge mask that found it. - */ -$a_eos: - negq t8, t12 # E : find low bit set - and t8, t12, t12 # E : - - /* We're doing a partial word store and so need to combine - our source and original destination words. */ - ldq_u t1, 0(a0) # L : - subq t12, 1, t6 # E : - - or t12, t6, t8 # E : - zapnot t0, t8, t0 # U : clear src bytes > null - zap t1, t8, t1 # U : clear dst bytes <= null - or t0, t1, t0 # E : - - stq_u t0, 0(a0) # L : - br $finish_up # L0 : - nop - nop - - /* Add the end-of-count bit to the eos detection bitmask. */ - .align 4 -$a_eoc: - or t10, t8, t8 - br $a_eos - nop - nop - - -/* The source and destination are not co-aligned. Align the destination - and cope. We have to be very careful about not reading too much and - causing a SEGV. */ - - .align 4 -$u_head: - /* We know just enough now to be able to assemble the first - full source word. We can still find a zero at the end of it - that prevents us from outputting the whole thing. - - On entry to this basic block: - t0 == the first dest word, unmasked - t1 == the shifted low bits of the first source word - t6 == bytemask that is -1 in dest word bytes */ - - EX( ldq_u t2, 8(a1) ) # L : load second src word - addq a1, 8, a1 # E : - mskql t0, a0, t0 # U : mask trailing garbage in dst - extqh t2, a1, t4 # U : - - or t1, t4, t1 # E : first aligned src word complete - mskqh t1, a0, t1 # U : mask leading garbage in src - or t0, t1, t0 # E : first output word complete - or t0, t6, t6 # E : mask original data for zero test - - cmpbge zero, t6, t8 # E : - beq a2, $u_eocfin # U : - bne t8, $u_final # U : bad news - 2nd branch in a quad - lda t6, -1 # E : mask out the bits we have - - mskql t6, a1, t6 # U : already seen - stq_u t0, 0(a0) # L : store first output word - or t6, t2, t2 # E : - cmpbge zero, t2, t8 # E : find nulls in second partial - - addq a0, 8, a0 # E : - subq a2, 1, a2 # E : - bne t8, $u_late_head_exit # U : - nop - - /* Finally, we've got all the stupid leading edge cases taken care - of and we can set up to enter the main loop. */ - - extql t2, a1, t1 # U : position hi-bits of lo word - EX( ldq_u t2, 8(a1) ) # L : read next high-order source word - addq a1, 8, a1 # E : - cmpbge zero, t2, t8 # E : - - beq a2, $u_eoc # U : - bne t8, $u_eos # U : - nop - nop - - /* Unaligned copy main loop. In order to avoid reading too much, - the loop is structured to detect zeros in aligned source words. - This has, unfortunately, effectively pulled half of a loop - iteration out into the head and half into the tail, but it does - prevent nastiness from accumulating in the very thing we want - to run as fast as possible. - - On entry to this basic block: - t1 == the shifted high-order bits from the previous source word - t2 == the unshifted current source word - - We further know that t2 does not contain a null terminator. */ - - /* - * Extra nops here: - * separate load quads from store quads - * only one branch/quad to permit predictor training - */ - - .align 4 -$u_loop: - extqh t2, a1, t0 # U : extract high bits for current word - addq a1, 8, a1 # E : - extql t2, a1, t3 # U : extract low bits for next time - addq a0, 8, a0 # E : - - or t0, t1, t0 # E : current dst word now complete - EX( ldq_u t2, 0(a1) ) # L : load high word for next time - subq a2, 1, a2 # E : - nop - - stq_u t0, -8(a0) # L : save the current word - mov t3, t1 # E : - cmpbge zero, t2, t8 # E : test new word for eos - beq a2, $u_eoc # U : - - beq t8, $u_loop # U : - nop - nop - nop - - /* We've found a zero somewhere in the source word we just read. - If it resides in the lower half, we have one (probably partial) - word to write out, and if it resides in the upper half, we - have one full and one partial word left to write out. - - On entry to this basic block: - t1 == the shifted high-order bits from the previous source word - t2 == the unshifted current source word. */ - .align 4 -$u_eos: - extqh t2, a1, t0 # U : - or t0, t1, t0 # E : first (partial) source word complete - cmpbge zero, t0, t8 # E : is the null in this first bit? - nop - - bne t8, $u_final # U : - stq_u t0, 0(a0) # L : the null was in the high-order bits - addq a0, 8, a0 # E : - subq a2, 1, a2 # E : - - .align 4 -$u_late_head_exit: - extql t2, a1, t0 # U : - cmpbge zero, t0, t8 # E : - or t8, t10, t6 # E : - cmoveq a2, t6, t8 # E : - - /* Take care of a final (probably partial) result word. - On entry to this basic block: - t0 == assembled source word - t8 == cmpbge mask that found the null. */ - .align 4 -$u_final: - negq t8, t6 # E : isolate low bit set - and t6, t8, t12 # E : - ldq_u t1, 0(a0) # L : - subq t12, 1, t6 # E : - - or t6, t12, t8 # E : - zapnot t0, t8, t0 # U : kill source bytes > null - zap t1, t8, t1 # U : kill dest bytes <= null - or t0, t1, t0 # E : - - stq_u t0, 0(a0) # E : - br $finish_up # U : - nop - nop - - .align 4 -$u_eoc: # end-of-count - extqh t2, a1, t0 # U : - or t0, t1, t0 # E : - cmpbge zero, t0, t8 # E : - nop - - .align 4 -$u_eocfin: # end-of-count, final word - or t10, t8, t8 # E : - br $u_final # U : - nop - nop - - /* Unaligned copy entry point. */ - .align 4 -$unaligned: - - srl a3, 3, a2 # U : a2 = loop counter = (count - 1)/8 - and a0, 7, t4 # E : find dest misalignment - and a1, 7, t5 # E : find src misalignment - mov zero, t0 # E : - - /* Conditionally load the first destination word and a bytemask - with 0xff indicating that the destination byte is sacrosanct. */ - - mov zero, t6 # E : - beq t4, 1f # U : - ldq_u t0, 0(a0) # L : - lda t6, -1 # E : - - mskql t6, a0, t6 # E : - nop - nop - nop - - .align 4 -1: - subq a1, t4, a1 # E : sub dest misalignment from src addr - /* If source misalignment is larger than dest misalignment, we need - extra startup checks to avoid SEGV. */ - cmplt t4, t5, t12 # E : - extql t1, a1, t1 # U : shift src into place - lda t2, -1 # E : for creating masks later - - beq t12, $u_head # U : - mskqh t2, t5, t2 # U : begin src byte validity mask - cmpbge zero, t1, t8 # E : is there a zero? - nop - - extql t2, a1, t2 # U : - or t8, t10, t5 # E : test for end-of-count too - cmpbge zero, t2, t3 # E : - cmoveq a2, t5, t8 # E : Latency=2, extra map slot - - nop # E : goes with cmov - andnot t8, t3, t8 # E : - beq t8, $u_head # U : - nop - - /* At this point we've found a zero in the first partial word of - the source. We need to isolate the valid source data and mask - it into the original destination data. (Incidentally, we know - that we'll need at least one byte of that original dest word.) */ - - ldq_u t0, 0(a0) # L : - negq t8, t6 # E : build bitmask of bytes <= zero - mskqh t1, t4, t1 # U : - and t6, t8, t12 # E : - - subq t12, 1, t6 # E : - or t6, t12, t8 # E : - zapnot t2, t8, t2 # U : prepare source word; mirror changes - zapnot t1, t8, t1 # U : to source validity mask - - andnot t0, t2, t0 # E : zero place for source to reside - or t0, t1, t0 # E : and put it there - stq_u t0, 0(a0) # L : - nop - - .align 4 -$finish_up: - zapnot t0, t12, t4 # U : was last byte written null? - and t12, 0xf0, t3 # E : binary search for the address of the - cmovne t4, 1, t4 # E : Latency=2, extra map slot - nop # E : with cmovne - - and t12, 0xcc, t2 # E : last byte written - and t12, 0xaa, t1 # E : - cmovne t3, 4, t3 # E : Latency=2, extra map slot - nop # E : with cmovne - - bic a0, 7, t0 - cmovne t2, 2, t2 # E : Latency=2, extra map slot - nop # E : with cmovne - nop - - cmovne t1, 1, t1 # E : Latency=2, extra map slot - nop # E : with cmovne - addq t0, t3, t0 # E : - addq t1, t2, t1 # E : - - addq t0, t1, t0 # E : - addq t0, t4, t0 # add one if we filled the buffer - subq t0, v0, v0 # find string length - ret # L0 : - - .align 4 -$zerolength: - nop - nop - nop - clr v0 - -$exception: - nop - nop - nop - ret - - .end __strncpy_from_user |