52 lines
2.0 KiB
Diff
52 lines
2.0 KiB
Diff
commit 9b7651410375ec8848a1944992d663d514db4ba7
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Author: Stefan Liebler <stli@linux.ibm.com>
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Date: Thu Jul 11 11:28:53 2024 +0200
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s390x: Fix segfault in wcsncmp [BZ #31934]
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The z13/vector-optimized wcsncmp implementation segfaults if n=1
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and there is only one character (equal on both strings) before
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the page end. Then it loads and compares one character and misses
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to check n again. The following load fails.
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This patch removes the extra load and compare of the first character
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and just start with the loop which uses vector-load-to-block-boundary.
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This code-path also checks n.
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With this patch both tests are passing:
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- the simplified one mentioned in the bugzilla 31934
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- the full one in Florian Weimer's patch:
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"manual: Document a GNU extension for strncmp/wcsncmp"
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(https://patchwork.sourceware.org/project/glibc/patch/874j9eml6y.fsf@oldenburg.str.redhat.com/):
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On s390x-linux-gnu (z16), the new wcsncmp test fails due to bug 31934.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/sysdeps/s390/wcsncmp-vx.S b/sysdeps/s390/wcsncmp-vx.S
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index bf6dfa6bc2..8b081567a2 100644
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--- a/sysdeps/s390/wcsncmp-vx.S
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+++ b/sysdeps/s390/wcsncmp-vx.S
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@@ -59,14 +59,7 @@ ENTRY(WCSNCMP_Z13)
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sllg %r4,%r4,2 /* Convert character-count to byte-count. */
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locgrne %r4,%r1 /* Use max byte-count, if bit 0/1 was one. */
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- /* Check first character without vector load. */
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- lghi %r5,4 /* current_len = 4 bytes. */
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- /* Check s1/2[0]. */
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- lt %r0,0(%r2)
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- l %r1,0(%r3)
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- je .Lend_cmp_one_char
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- crjne %r0,%r1,.Lend_cmp_one_char
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-
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+ lghi %r5,0 /* current_len = 0 bytes. */
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.Lloop:
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vlbb %v17,0(%r5,%r3),6 /* Load s2 to block boundary. */
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vlbb %v16,0(%r5,%r2),6 /* Load s1 to block boundary. */
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@@ -167,7 +160,6 @@ ENTRY(WCSNCMP_Z13)
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srl %r4,2 /* And convert it to character-index. */
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vlgvf %r0,%v16,0(%r4) /* Load character-values. */
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vlgvf %r1,%v17,0(%r4)
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-.Lend_cmp_one_char:
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cr %r0,%r1
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je .Lend_equal
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lghi %r2,1
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