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author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2015-02-12 13:08:27 +0100 |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-03-25 11:49:33 +0100 |
commit | 5a79859ae0f35d25c67a03e82bf0c80592f16a39 (patch) | |
tree | 37264d49f069812f19ced94e6ae171814fb7e498 /arch/s390/lib/qrnnd.S | |
parent | 1833c9f647e9bda1cd24653ff8f9c207b5f5b911 (diff) | |
download | lwn-5a79859ae0f35d25c67a03e82bf0c80592f16a39.tar.gz lwn-5a79859ae0f35d25c67a03e82bf0c80592f16a39.zip |
s390: remove 31 bit support
Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.
The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.
Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/lib/qrnnd.S')
-rw-r--r-- | arch/s390/lib/qrnnd.S | 78 |
1 files changed, 0 insertions, 78 deletions
diff --git a/arch/s390/lib/qrnnd.S b/arch/s390/lib/qrnnd.S deleted file mode 100644 index d321329130ec..000000000000 --- a/arch/s390/lib/qrnnd.S +++ /dev/null @@ -1,78 +0,0 @@ -# S/390 __udiv_qrnnd - -#include <linux/linkage.h> - -# r2 : &__r -# r3 : upper half of 64 bit word n -# r4 : lower half of 64 bit word n -# r5 : divisor d -# the reminder r of the division is to be stored to &__r and -# the quotient q is to be returned - - .text -ENTRY(__udiv_qrnnd) - st %r2,24(%r15) # store pointer to reminder for later - lr %r0,%r3 # reload n - lr %r1,%r4 - ltr %r2,%r5 # reload and test divisor - jp 5f - # divisor >= 0x80000000 - srdl %r0,2 # n/4 - srl %r2,1 # d/2 - slr %r1,%r2 # special case if last bit of d is set - brc 3,0f # (n/4) div (n/2) can overflow by 1 - ahi %r0,-1 # trick: subtract n/2, then divide -0: dr %r0,%r2 # signed division - ahi %r1,1 # trick part 2: add 1 to the quotient - # now (n >> 2) = (d >> 1) * %r1 + %r0 - lhi %r3,1 - nr %r3,%r1 # test last bit of q - jz 1f - alr %r0,%r2 # add (d>>1) to r -1: srl %r1,1 # q >>= 1 - # now (n >> 2) = (d&-2) * %r1 + %r0 - lhi %r3,1 - nr %r3,%r5 # test last bit of d - jz 2f - slr %r0,%r1 # r -= q - brc 3,2f # borrow ? - alr %r0,%r5 # r += d - ahi %r1,-1 -2: # now (n >> 2) = d * %r1 + %r0 - alr %r1,%r1 # q <<= 1 - alr %r0,%r0 # r <<= 1 - brc 12,3f # overflow on r ? - slr %r0,%r5 # r -= d - ahi %r1,1 # q += 1 -3: lhi %r3,2 - nr %r3,%r4 # test next to last bit of n - jz 4f - ahi %r0,1 # r += 1 -4: clr %r0,%r5 # r >= d ? - jl 6f - slr %r0,%r5 # r -= d - ahi %r1,1 # q += 1 - # now (n >> 1) = d * %r1 + %r0 - j 6f -5: # divisor < 0x80000000 - srdl %r0,1 - dr %r0,%r2 # signed division - # now (n >> 1) = d * %r1 + %r0 -6: alr %r1,%r1 # q <<= 1 - alr %r0,%r0 # r <<= 1 - brc 12,7f # overflow on r ? - slr %r0,%r5 # r -= d - ahi %r1,1 # q += 1 -7: lhi %r3,1 - nr %r3,%r4 # isolate last bit of n - alr %r0,%r3 # r += (n & 1) - clr %r0,%r5 # r >= d ? - jl 8f - slr %r0,%r5 # r -= d - ahi %r1,1 # q += 1 -8: # now n = d * %r1 + %r0 - l %r2,24(%r15) - st %r0,0(%r2) - lr %r2,%r1 - br %r14 - .end __udiv_qrnnd |