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Diffstat (limited to 'arch/alpha/lib/strncpy_from_user.S')
| -rw-r--r-- | arch/alpha/lib/strncpy_from_user.S | 339 |
1 files changed, 0 insertions, 339 deletions
diff --git a/arch/alpha/lib/strncpy_from_user.S b/arch/alpha/lib/strncpy_from_user.S deleted file mode 100644 index 73ee211..0000000 --- a/arch/alpha/lib/strncpy_from_user.S +++ /dev/null @@ -1,339 +0,0 @@ -/* - * arch/alpha/lib/strncpy_from_user.S - * Contributed by Richard Henderson (rth@tamu.edu) - * - * 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. - */ - - -#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, $26 - .prologue 0 - - .align 3 -$aligned: - /* On entry to this basic block: - t0 == the first destination word for masking back in - t1 == the first source word. */ - - /* Create the 1st output word and detect 0's in the 1st input word. */ - lda t2, -1 # e1 : build a mask against false zero - mskqh t2, a1, t2 # e0 : detection in the src word - mskqh t1, a1, t3 # e0 : - ornot t1, t2, t2 # .. e1 : - mskql t0, a1, t0 # e0 : assemble the first output word - cmpbge zero, t2, t8 # .. e1 : bits set iff null found - or t0, t3, t0 # e0 : - beq a2, $a_eoc # .. e1 : - bne t8, $a_eos # .. e1 : - - /* On entry to this basic block: - t0 == a source word not containing a null. */ - -$a_loop: - stq_u t0, 0(a0) # e0 : - addq a0, 8, a0 # .. e1 : - EX( ldq_u t0, 0(a1) ) # e0 : - addq a1, 8, a1 # .. e1 : - subq a2, 1, a2 # e0 : - cmpbge zero, t0, t8 # .. e1 (stall) - beq a2, $a_eoc # e1 : - beq t8, $a_loop # e1 : - - /* Take care of the final (partial) word store. At this point - the end-of-count bit is set in t8 iff it applies. - - On entry to this basic block we have: - t0 == the source word containing the null - t8 == the cmpbge mask that found it. */ - -$a_eos: - negq t8, t12 # e0 : find low bit set - and t8, t12, t12 # e1 (stall) - - /* For the sake of the cache, don't read a destination word - if we're not going to need it. */ - and t12, 0x80, t6 # e0 : - bne t6, 1f # .. e1 (zdb) - - /* We're doing a partial word store and so need to combine - our source and original destination words. */ - ldq_u t1, 0(a0) # e0 : - subq t12, 1, t6 # .. e1 : - or t12, t6, t8 # e0 : - unop # - zapnot t0, t8, t0 # e0 : clear src bytes > null - zap t1, t8, t1 # .. e1 : clear dst bytes <= null - or t0, t1, t0 # e1 : - -1: stq_u t0, 0(a0) - br $finish_up - - /* Add the end-of-count bit to the eos detection bitmask. */ -$a_eoc: - or t10, t8, t8 - br $a_eos - - /*** The Function Entry Point ***/ - .align 3 -__strncpy_from_user: - mov a0, v0 # save the string start - beq a2, $zerolength - - /* Are source and destination co-aligned? */ - xor a0, a1, t1 # e0 : - and a0, 7, t0 # .. e1 : find dest misalignment - and t1, 7, t1 # e0 : - addq a2, t0, a2 # .. e1 : bias count by dest misalignment - subq a2, 1, a2 # e0 : - and a2, 7, t2 # e1 : - srl a2, 3, a2 # e0 : a2 = loop counter = (count - 1)/8 - addq zero, 1, t10 # .. e1 : - sll t10, t2, t10 # e0 : t10 = bitmask of last count byte - bne t1, $unaligned # .. e1 : - - /* We are co-aligned; take care of a partial first word. */ - - EX( ldq_u t1, 0(a1) ) # e0 : load first src word - addq a1, 8, a1 # .. e1 : - - beq t0, $aligned # avoid loading dest word if not needed - ldq_u t0, 0(a0) # e0 : - br $aligned # .. e1 : - - -/* The source and destination are not co-aligned. Align the destination - and cope. We have to be very careful about not reading too much and - causing a SEGV. */ - - .align 3 -$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) ) # e0 : load second src word - addq a1, 8, a1 # .. e1 : - mskql t0, a0, t0 # e0 : mask trailing garbage in dst - extqh t2, a1, t4 # e0 : - or t1, t4, t1 # e1 : first aligned src word complete - mskqh t1, a0, t1 # e0 : mask leading garbage in src - or t0, t1, t0 # e0 : first output word complete - or t0, t6, t6 # e1 : mask original data for zero test - cmpbge zero, t6, t8 # e0 : - beq a2, $u_eocfin # .. e1 : - bne t8, $u_final # e1 : - - lda t6, -1 # e1 : mask out the bits we have - mskql t6, a1, t6 # e0 : already seen - stq_u t0, 0(a0) # e0 : store first output word - or t6, t2, t2 # .. e1 : - cmpbge zero, t2, t8 # e0 : find nulls in second partial - addq a0, 8, a0 # .. e1 : - subq a2, 1, a2 # e0 : - bne t8, $u_late_head_exit # .. e1 : - - /* 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 # e0 : position hi-bits of lo word - EX( ldq_u t2, 8(a1) ) # .. e1 : read next high-order source word - addq a1, 8, a1 # e0 : - cmpbge zero, t2, t8 # e1 (stall) - beq a2, $u_eoc # e1 : - bne t8, $u_eos # e1 : - - /* Unaligned copy main loop. In order to avoid reading too much, - the loop is structured to detect zeros in aligned source words. - This has, unfortunately, effectively pulled half of a loop - iteration out into the head and half into the tail, but it does - prevent nastiness from accumulating in the very thing we want - to run as fast as possible. - - On entry to this basic block: - t1 == the shifted high-order bits from the previous source word - t2 == the unshifted current source word - - We further know that t2 does not contain a null terminator. */ - - .align 3 -$u_loop: - extqh t2, a1, t0 # e0 : extract high bits for current word - addq a1, 8, a1 # .. e1 : - extql t2, a1, t3 # e0 : extract low bits for next time - addq a0, 8, a0 # .. e1 : - or t0, t1, t0 # e0 : current dst word now complete - EX( ldq_u t2, 0(a1) ) # .. e1 : load high word for next time - stq_u t0, -8(a0) # e0 : save the current word - mov t3, t1 # .. e1 : - subq a2, 1, a2 # e0 : - cmpbge zero, t2, t8 # .. e1 : test new word for eos - beq a2, $u_eoc # e1 : - beq t8, $u_loop # e1 : - - /* We've found a zero somewhere in the source word we just read. - If it resides in the lower half, we have one (probably partial) - word to write out, and if it resides in the upper half, we - have one full and one partial word left to write out. - - On entry to this basic block: - t1 == the shifted high-order bits from the previous source word - t2 == the unshifted current source word. */ -$u_eos: - extqh t2, a1, t0 # e0 : - or t0, t1, t0 # e1 : first (partial) source word complete - - cmpbge zero, t0, t8 # e0 : is the null in this first bit? - bne t8, $u_final # .. e1 (zdb) - - stq_u t0, 0(a0) # e0 : the null was in the high-order bits - addq a0, 8, a0 # .. e1 : - subq a2, 1, a2 # e1 : - -$u_late_head_exit: - extql t2, a1, t0 # .. e0 : - cmpbge zero, t0, t8 # e0 : - or t8, t10, t6 # e1 : - cmoveq a2, t6, t8 # e0 : - nop # .. e1 : - - /* 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. */ -$u_final: - negq t8, t6 # e0 : isolate low bit set - and t6, t8, t12 # e1 : - - and t12, 0x80, t6 # e0 : avoid dest word load if we can - bne t6, 1f # .. e1 (zdb) - - ldq_u t1, 0(a0) # e0 : - subq t12, 1, t6 # .. e1 : - or t6, t12, t8 # e0 : - zapnot t0, t8, t0 # .. e1 : kill source bytes > null - zap t1, t8, t1 # e0 : kill dest bytes <= null - or t0, t1, t0 # e1 : - -1: stq_u t0, 0(a0) # e0 : - br $finish_up - -$u_eoc: # end-of-count - extqh t2, a1, t0 - or t0, t1, t0 - cmpbge zero, t0, t8 - -$u_eocfin: # end-of-count, final word - or t10, t8, t8 - br $u_final - - /* Unaligned copy entry point. */ - .align 3 -$unaligned: - - EX( ldq_u t1, 0(a1) ) # e0 : load first source word - - and a0, 7, t4 # .. e1 : find dest misalignment - and a1, 7, t5 # e0 : find src misalignment - - /* Conditionally load the first destination word and a bytemask - with 0xff indicating that the destination byte is sacrosanct. */ - - mov zero, t0 # .. e1 : - mov zero, t6 # e0 : - beq t4, 1f # .. e1 : - ldq_u t0, 0(a0) # e0 : - lda t6, -1 # .. e1 : - mskql t6, a0, t6 # e0 : -1: - subq a1, t4, a1 # .. e1 : 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 # e1 : - extql t1, a1, t1 # .. e0 : shift src into place - lda t2, -1 # e0 : for creating masks later - beq t12, $u_head # e1 : - - mskqh t2, t5, t2 # e0 : begin src byte validity mask - cmpbge zero, t1, t8 # .. e1 : is there a zero? - extql t2, a1, t2 # e0 : - or t8, t10, t5 # .. e1 : test for end-of-count too - cmpbge zero, t2, t3 # e0 : - cmoveq a2, t5, t8 # .. e1 : - andnot t8, t3, t8 # e0 : - beq t8, $u_head # .. e1 (zdb) - - /* At this point we've found a zero in the first partial word of - the source. We need to isolate the valid source data and mask - it into the original destination data. (Incidentally, we know - that we'll need at least one byte of that original dest word.) */ - - ldq_u t0, 0(a0) # e0 : - negq t8, t6 # .. e1 : build bitmask of bytes <= zero - mskqh t1, t4, t1 # e0 : - and t6, t8, t12 # .. e1 : - subq t12, 1, t6 # e0 : - or t6, t12, t8 # e1 : - - zapnot t2, t8, t2 # e0 : prepare source word; mirror changes - zapnot t1, t8, t1 # .. e1 : to source validity mask - - andnot t0, t2, t0 # e0 : zero place for source to reside - or t0, t1, t0 # e1 : and put it there - stq_u t0, 0(a0) # e0 : - -$finish_up: - zapnot t0, t12, t4 # was last byte written null? - cmovne t4, 1, t4 - - and t12, 0xf0, t3 # binary search for the address of the - and t12, 0xcc, t2 # last byte written - and t12, 0xaa, t1 - bic a0, 7, t0 - cmovne t3, 4, t3 - cmovne t2, 2, t2 - cmovne t1, 1, t1 - addq t0, t3, t0 - addq t1, t2, t1 - addq t0, t1, t0 - addq t0, t4, t0 # add one if we filled the buffer - - subq t0, v0, v0 # find string length - ret - -$zerolength: - clr v0 -$exception: - ret - - .end __strncpy_from_user |
