Re: [RFC PATCH v2 12/31] kvx: Add other common headers

Hi Yann, On Fri, Jan 20, 2023 at 03:09:43PM +0100, Yann Sionneau wrote: > +#include <linux/random.h> > +#include <linux/version.h> > + > +extern unsigned long __stack_chk_guard; > + > +/* > + * Initialize the stackprotector canary value. > + * > + * NOTE: this must only be called from functions that never return, > + * and it must always be inlined. > + */ > +static __always_inline void boot_init_stack_canary(void) > +{ > + unsigned long canary; > + > + /* Try to get a semi random initial value. */ > + get_random_bytes(&canary, sizeof(canary)); > + canary ^= LINUX_VERSION_CODE; > + canary &= CANARY_MASK; > + > + current->stack_canary = canary; > + __stack_chk_guard = current->stack_canary; > +} You should rewrite this as: current->stack_canary = get_random_canary(); __stack_chk_guard = current->stack_canary; which is what the other archs all now do. (They didn't used to, and this looks like it's simply based on older code.)

> +#define get_cycles get_cycles > + > +#include <asm/sfr.h> > +#include <asm-generic/timex.h> > + > +static inline cycles_t get_cycles(void) > +{ > + return kvx_sfr_get(PM0); > +} Glad to see this CPU has a cycle counter. Out of curiosity, what is its resolution?

Also, related, does this CPU happen to have a "RDRAND"-like instruction?

(I don't know anything about kvx or even what it is.)