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riscv: hwprobe: initialize pair->value in hwprobe_one_pair()

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The vendor-extension handlers reached from hwprobe_one_pair()
(hwprobe_isa_vendor_ext_thead_0() and friends) only OR the present bits
into pair->value via VENDOR_EXTENSION_SUPPORTED() and clear their own
missing bits; they assume the caller has already zeroed pair->value.

That holds for hwprobe_get_values() (it zeroes each pair) and
hwprobe_get_cpus() (it re-initializes its scratch pair per key), but not
for complete_hwprobe_vdso_data(), which reuses a single pair across all
keys without re-zeroing. A vendor key therefore inherits stale bits from
the previously probed key, and the wrong value is cached in the vDSO
all_cpu_hwprobe_values[] and handed to userspace on the fast patih.

Zero pair->value once at the top of hwprobe_one_pair() so every handler
starts from a clean value regardless of the caller, and drop the now
redundant zeroing in the *_BLOCK_SIZE cases. hwprobe_isa_ext0() keeps its
own zeroing because hwprobe_ext0_has() calls it directly, bypassing
hwprobe_one_pair().

Fixes: a5ea53da65 ("riscv: hwprobe: Add thead vendor extension probing")
Signed-off-by: Andy Chiu <tchiu@tenstorrent.com>
Reviewed-by: Jesse Taube <jtaubepe@redhat.com>
Link: https://patch.msgid.link/20260725001614.2578617-2-tchiu@tenstorrent.com
Cc: stable@vger.kernel.org
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Andy Chiu 2026-08-31 19:11:23 -06:00 committed by Paul Walmsley
parent 12381af010
commit d0fc6fab20
1 changed files with 2 additions and 3 deletions
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5
arch/riscv/kernel/sys_hwprobe.c
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@ -297,6 +297,8 @@ static u64 hwprobe_vec_misaligned(const struct cpumask *cpus)
static void hwprobe_one_pair(struct riscv_hwprobe *pair,
const struct cpumask *cpus)
{
pair->value = 0;
switch (pair->key) {
case RISCV_HWPROBE_KEY_MVENDORID:
case RISCV_HWPROBE_KEY_MARCHID:
@ -331,17 +333,14 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
break;
case RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE:
pair->value = 0;
if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOZ))
pair->value = riscv_cboz_block_size;
break;
case RISCV_HWPROBE_KEY_ZICBOM_BLOCK_SIZE:
pair->value = 0;
if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOM))
pair->value = riscv_cbom_block_size;
break;
case RISCV_HWPROBE_KEY_ZICBOP_BLOCK_SIZE:
pair->value = 0;
if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOP))
pair->value = riscv_cbop_block_size;
break;