[PATCH v10 08/40] arm64/gcs: Provide put_user_gcs()

Mark Brown
2024-08-01T12:58:14Z

In order for EL1 to write to an EL0 GCS it must use the GCSSTTR instruction
rather than a normal STTR. Provide a put_user_gcs() which does this.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/uaccess.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 6aba10e38d1c..ecdd47cf1d01 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -522,6 +522,24 @@ static inline int gcssttr(unsigned long __user *addr, unsigned long val)
return err;
}

+static inline void put_user_gcs(unsigned long val, unsigned long __user *addr,
+ int *err)
+{
+ int ret;
+
+ if (!access_ok((char __user *)addr, sizeof(u64))) {
+ *err = -EFAULT;
+ return;
+ }
+
+ uaccess_ttbr0_enable();
+ ret = gcssttr(addr, val);
+ if (ret != 0)
+ *err = ret;
+ uaccess_ttbr0_disable();
+}
+
+
#endif /* CONFIG_ARM64_GCS */

#endif /* __ASM_UACCESS_H */

--
2.39.2