From d0fc6fab20460add1f27402cd8b945d094a56b21 Mon Sep 17 00:00:00 2001 From: Andy Chiu Date: Mon, 31 Aug 2026 19:11:23 -0600 Subject: [PATCH] riscv: hwprobe: initialize pair->value in hwprobe_one_pair() 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: a5ea53da65c5 ("riscv: hwprobe: Add thead vendor extension probing") Signed-off-by: Andy Chiu Reviewed-by: Jesse Taube Link: https://patch.msgid.link/20260725001614.2578617-2-tchiu@tenstorrent.com Cc: stable@vger.kernel.org Signed-off-by: Paul Walmsley --- arch/riscv/kernel/sys_hwprobe.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c index bd6ca7d769da..7818e1d32622 100644 --- a/arch/riscv/kernel/sys_hwprobe.c +++ b/arch/riscv/kernel/sys_hwprobe.c @@ -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;