Some userspace applications (OpenJDK for instance) uses the free bits in pointers to insert additional information for their own logic. Currently they rely on parsing /proc/cpuinfo to obtain the current value of virtual address used bits [1]. Exporting VA_BITS through hwprobe will allow for a more stable interface to be used. Link: https://github.com/openjdk/jdk/blob/master/src/hotspot/os_cpu/linux_riscv/vm_version_linux_riscv.cpp#L171 [1] Signed-off-by: Clément Léger <cleger@xxxxxxxxxxxx> --- Documentation/arch/riscv/hwprobe.rst | 3 +++ arch/riscv/include/asm/hwprobe.h | 2 +- arch/riscv/include/uapi/asm/hwprobe.h | 1 + arch/riscv/kernel/sys_hwprobe.c | 3 +++ 4 files changed, 8 insertions(+), 1 deletion(-) diff --git a/Documentation/arch/riscv/hwprobe.rst b/Documentation/arch/riscv/hwprobe.rst index b2bcc9eed9aa..6f198c6ed4f0 100644 --- a/Documentation/arch/riscv/hwprobe.rst +++ b/Documentation/arch/riscv/hwprobe.rst @@ -210,3 +210,6 @@ The following keys are defined: * :c:macro:`RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE`: An unsigned int which represents the size of the Zicboz block in bytes. + +* :c:macro:`RISCV_HWPROBE_KEY_VA_BITS`: An unsigned long which + represent the number of bits used to store virtual addresses. diff --git a/arch/riscv/include/asm/hwprobe.h b/arch/riscv/include/asm/hwprobe.h index 630507dff5ea..150a9877b0af 100644 --- a/arch/riscv/include/asm/hwprobe.h +++ b/arch/riscv/include/asm/hwprobe.h @@ -8,7 +8,7 @@ #include <uapi/asm/hwprobe.h> -#define RISCV_HWPROBE_MAX_KEY 6 +#define RISCV_HWPROBE_MAX_KEY 7 static inline bool riscv_hwprobe_key_is_valid(__s64 key) { diff --git a/arch/riscv/include/uapi/asm/hwprobe.h b/arch/riscv/include/uapi/asm/hwprobe.h index 9f2a8e3ff204..2a5006cddb7b 100644 --- a/arch/riscv/include/uapi/asm/hwprobe.h +++ b/arch/riscv/include/uapi/asm/hwprobe.h @@ -67,6 +67,7 @@ struct riscv_hwprobe { #define RISCV_HWPROBE_MISALIGNED_UNSUPPORTED (4 << 0) #define RISCV_HWPROBE_MISALIGNED_MASK (7 << 0) #define RISCV_HWPROBE_KEY_ZICBOZ_BLOCK_SIZE 6 +#define RISCV_HWPROBE_KEY_VA_BITS 7 /* Increase RISCV_HWPROBE_MAX_KEY when adding items. */ /* Flags */ diff --git a/arch/riscv/kernel/sys_hwprobe.c b/arch/riscv/kernel/sys_hwprobe.c index a7c56b41efd2..328435836e36 100644 --- a/arch/riscv/kernel/sys_hwprobe.c +++ b/arch/riscv/kernel/sys_hwprobe.c @@ -202,6 +202,9 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair, if (hwprobe_ext0_has(cpus, RISCV_HWPROBE_EXT_ZICBOZ)) pair->value = riscv_cboz_block_size; break; + case RISCV_HWPROBE_KEY_VA_BITS: + pair->value = VA_BITS; + break; /* * For forward compatibility, unknown keys don't fail the whole -- 2.43.0
