On Thu, Jul 23, 2015 at 9:06 AM, Steven Rostedt <[email protected]> wrote: > On Thu, 23 Jul 2015 08:31:41 -0700 > Andy Lutomirski <[email protected]> wrote: > > >> - if (!boot_cpu_has(X86_FEATURE_SEP)) >> + /* >> + * On 64-bit CPUs, enable SEP unconditionally. On Intel CPUs, >> + * it works and we use it. On AMD CPUs, the MSRs exist but EIP >> + * is truncated to 32 bits. This doesn't matter because AMD >> + * CPUs disallow SYSENTER in long mode. If AMD ever decides to >> + * support SYSENTER, then they'll have to fix the truncation >> + * issue, and this code will work as-is. >> + */ >> + >> + if (IS_ENABLED(CONFIG_X86_32) && !boot_cpu_has(X86_FEATURE_SEP)) >> goto out; >> >> +#ifdef CONFIG_X86_32 >> /* >> * We cache MSR_IA32_SYSENTER_CS's value in the TSS's ss1 field -- >> * see the big comment in struct x86_hw_tss's definition. >> */ >> tss->x86_tss.ss1 = __KERNEL_CS; >> +#endif >> >> wrmsrl_safe(MSR_IA32_SYSENTER_CS, __KERNEL_CS); >> wrmsrl_safe(MSR_IA32_SYSENTER_ESP, >> (unsigned long)tss + >> offsetofend(struct tss_struct, SYSENTER_stack)); >> +#ifdef CONFIG_X86_32 >> wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32); >> +#else >> + wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (unsigned >> long)entry_SYSENTER_compat); >> +#endif > > As an additional clean up, what impact would we have to just rename > entry_SYSENTER_compat to entry_SYSENTER_32 on x86_64? It would remove > the need for the above #ifdef logic.
I asked Ingo that at one point. I bet that, if we can get the ABIs to match, then we can do that. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
