70 lines
3.0 KiB
Diff
70 lines
3.0 KiB
Diff
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From d0b24cfdeb8bd64fa55154d79574352be33ecc51 Mon Sep 17 00:00:00 2001
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From: Peter Maydell <peter.maydell@linaro.org>
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Date: Fri, 15 Nov 2024 17:25:15 +0000
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Subject: [PATCH] tcg: Allow top bit of SIMD_DATA_BITS to be set in simd_desc()
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In simd_desc() we create a SIMD descriptor from various pieces
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including an arbitrary data value from the caller. We try to
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sanitize these to make sure everything will fit: the 'data' value
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needs to fit in the SIMD_DATA_BITS (== 22) sized field. However we
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do that sanitizing with:
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tcg_debug_assert(data == sextract32(data, 0, SIMD_DATA_BITS));
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This works for the case where the data is supposed to be considered
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as a signed integer (which can then be returned via simd_data()).
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However, some callers want to treat the data value as unsigned.
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Specifically, for the Arm SVE operations, make_svemte_desc()
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assembles a data value as a collection of fields, and it needs to use
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all 22 bits. Currently if MTE is enabled then its MTEDESC SIZEM1
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field may have the most significant bit set, and then it will trip
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this assertion.
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Loosen the assertion so that we only check that the data value will
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fit into the field in some way, either as a signed or as an unsigned
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value. This means we will fail to detect some kinds of bug in the
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callers, but we won't spuriously assert for intentional use of the
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data field as unsigned.
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Cc: qemu-stable@nongnu.org
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Fixes: db432672dc50e ("tcg: Add generic vector expanders")
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Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2601
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Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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Message-ID: <20241115172515.1229393-1-peter.maydell@linaro.org>
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Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
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Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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Signed-off-by: Zhongrui Tang <tangzhongrui_yewu@cmss.chinamobile.com>
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---
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tcg/tcg-op-gvec.c | 15 ++++++++++++++-
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1 file changed, 14 insertions(+), 1 deletion(-)
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diff --git a/tcg/tcg-op-gvec.c b/tcg/tcg-op-gvec.c
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index bb88943f79..733b44f105 100644
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--- a/tcg/tcg-op-gvec.c
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+++ b/tcg/tcg-op-gvec.c
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@@ -88,7 +88,20 @@ uint32_t simd_desc(uint32_t oprsz, uint32_t maxsz, int32_t data)
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uint32_t desc = 0;
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check_size_align(oprsz, maxsz, 0);
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- tcg_debug_assert(data == sextract32(data, 0, SIMD_DATA_BITS));
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+
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+ /*
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+ * We want to check that 'data' will fit into SIMD_DATA_BITS.
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+ * However, some callers want to treat the data as a signed
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+ * value (which they can later get back with simd_data())
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+ * and some want to treat it as an unsigned value.
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+ * So here we assert only that the data will fit into the
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+ * field in at least one way. This means that some invalid
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+ * values from the caller will not be detected, e.g. if the
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+ * caller wants to handle the value as a signed integer but
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+ * incorrectly passes us 1 << (SIMD_DATA_BITS - 1).
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+ */
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+ tcg_debug_assert(data == sextract32(data, 0, SIMD_DATA_BITS) ||
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+ data == extract32(data, 0, SIMD_DATA_BITS));
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oprsz = (oprsz / 8) - 1;
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maxsz = (maxsz / 8) - 1;
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--
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2.41.0.windows.1
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