100 lines
2.7 KiB
Diff
100 lines
2.7 KiB
Diff
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From 70ef4417837b690755feede0088331a28b102c65 Mon Sep 17 00:00:00 2001
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From: Andreas Arnez <arnez@linux.ibm.com>
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Date: Mon, 22 May 2023 18:57:35 +0200
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Subject: [PATCH 1/2] Bug 470132 - s390x: Fix the wrap-around case in VGM
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Valgrind's implementation of VGM is incomplete:
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* It doesn't support generating a wrap-around bit mask. Such a mask
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should result when the ending bit position is smaller than the starting
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bit position. Valgrind runs into an assertion failure instead.
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* It doesn't ignore unused bits in the I2 and I3 fields of the
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instruction, as it should.
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Fix this by re-implementing the main logic in s390_irgen_VGM().
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---
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VEX/priv/guest_s390_toIR.c | 57 +++++++++++++++-----------------------
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1 file changed, 22 insertions(+), 35 deletions(-)
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diff --git a/VEX/priv/guest_s390_toIR.c b/VEX/priv/guest_s390_toIR.c
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index 11dda41ef..d9d746c38 100644
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--- a/VEX/priv/guest_s390_toIR.c
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+++ b/VEX/priv/guest_s390_toIR.c
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@@ -16388,50 +16388,37 @@ s390_irgen_VGBM(UChar v1, UShort i2, UChar m3 __attribute__((unused)))
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static const HChar *
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s390_irgen_VGM(UChar v1, UShort i2, UChar m3)
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{
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- UChar from = (i2 & 0xff00) >> 8;
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- UChar to = (i2 & 0x00ff);
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- ULong value = 0UL;
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- IRType type = s390_vr_get_type(m3);
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- vassert(from <= to);
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-
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- UChar maxIndex = 0;
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- switch (type) {
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- case Ity_I8:
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- maxIndex = 7;
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- break;
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- case Ity_I16:
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- maxIndex = 15;
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- break;
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- case Ity_I32:
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- maxIndex = 31;
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- break;
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- case Ity_I64:
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- maxIndex = 63;
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- break;
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- default:
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- vpanic("s390_irgen_VGM: unknown type");
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- }
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-
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- for(UChar index = from; index <= to; index++) {
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- value |= (1ULL << (maxIndex - index));
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- }
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-
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- IRExpr *fillValue;
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- switch (type) {
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- case Ity_I8:
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+ s390_insn_assert("vgm", m3 <= 3);
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+
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+ UChar max_idx = (8 << m3) - 1;
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+ UChar from = max_idx & (i2 >> 8);
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+ UChar to = max_idx & i2;
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+ ULong all_one = (1ULL << max_idx << 1) - 1;
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+ ULong value = (all_one >> from) ^ (all_one >> to >> 1);
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+
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+ /* In case of wrap-around we now have a value that needs inverting:
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+ to from
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+ V V
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+ 00000111111111110000000000000000 */
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+ if (to < from)
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+ value ^= all_one;
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+
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+ IRExpr* fillValue;
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+ switch (m3) {
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+ case 0:
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fillValue = mkU8(value);
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break;
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- case Ity_I16:
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+ case 1:
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fillValue = mkU16(value);
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break;
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- case Ity_I32:
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+ case 2:
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fillValue = mkU32(value);
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break;
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- case Ity_I64:
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+ case 3:
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fillValue = mkU64(value);
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break;
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default:
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- vpanic("s390_irgen_VGM: unknown type");
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+ vpanic("s390_irgen_VGM: unknown element size");
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}
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s390_vr_fill(v1, fillValue);
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--
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2.40.1
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