On 12/06/2018 06:25 PM, Catalin Marinas wrote:
On Mon, Dec 03, 2018 at 01:55:18PM +0000, Julien Thierry wrote:diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 07c3408..cabfcae 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -233,6 +233,23 @@ static inline void uaccess_enable_not_uao(void) __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); }+#define unsafe_user_region_active uaccess_region_active+static inline bool uaccess_region_active(void) +{ + if (system_uses_ttbr0_pan()) { + u64 ttbr; + + ttbr = read_sysreg(ttbr1_el1); + return ttbr & TTBR_ASID_MASK;Nitpick: could write this in 1-2 lines.
True, I can do that in 1 line.
+ } else if (cpus_have_const_cap(ARM64_ALT_PAN_NOT_UAO)) { + return (read_sysreg(sctlr_el1) & SCTLR_EL1_SPAN) ? + false : + !read_sysreg_s(SYS_PSTATE_PAN); + }ARM64_ALT_PAN_NOT_UAO implies ARM64_HAS_PAN which implies SCTLR_EL1.SPAN is 0 at run-time. Is this to cope with the case of being called prior to cpu_enable_pan()?
Yes, the issue I can into is that for cpufeatures, .cpu_enable() callbacks are called inside stop_machine() which obviously might_sleep and so attempts to check whether user_access is on. But for features that get enabled before PAN, the PAN bit will be set.
Thanks, Julien
