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 Reviewed-by: Catalin Marinas catalin.marinas@arm.com 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 0db494b24dd0..5b91803201ef 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 */