Messages in this thread | | | Subject | Re: [PATCH v4 4/4] sparc64: Add support for ADI (Application Data Integrity) | From | Khalid Aziz <> | Date | Tue, 17 Jan 2017 12:32:46 -0700 |
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On 01/16/2017 09:39 PM, David Miller wrote: > From: Khalid Aziz <khalid.aziz@oracle.com> > Date: Wed, 11 Jan 2017 09:12:54 -0700 > >> + __asm__ __volatile__( >> + ".word 0xa1438000\n\t" /* rd %mcdper, %l0 */ > > Just use "rd %%asr14, %0" this way you don't have to play all of these > fixed register games which kill the code generated by gcc. If you > forcefully clobber a windowed register like %l0 it means the function > being emitted can never be a leaf function, tail calls are no longer > allowed, etc.
Hi David,
"rd %%asr14, %0" should work but does not due to bugs in assembler - <https://sourceware.org/ml/binutils/2016-03/msg00302.html>, and <https://sourceware.org/ml/binutils/2016-03/msg00303.html>. These bugs were fixed in binutils 2.27 but older assemblers will cause kernel build to fail. Using byte coded equivalent is the safest option.
> >> + ".word 0x9d800011\n\t" /* wr %g0, %l1, %mcdper */ > > Likewise use "wr %%g0, %0, %%asr14" > >> + ".word 0xaf900001\n\t" /* wrpr %g0, %g1, %pmcdper */ > > Hmmm, which %asr encodes %pmcdper?
%pmcdper is not an asr, rather a privileged register (pr23).
Thanks, Khalid
> >> diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c >> index 8a6982d..68b03bf 100644 >> --- a/arch/sparc/kernel/mdesc.c >> +++ b/arch/sparc/kernel/mdesc.c >> @@ -20,6 +20,7 @@ >> #include <asm/uaccess.h> >> #include <asm/oplib.h> >> #include <asm/smp.h> >> +#include <asm/adi.h> >> >> /* Unlike the OBP device tree, the machine description is a full-on >> * DAG. An arbitrary number of ARCs are possible from one >> @@ -1104,5 +1105,8 @@ void __init sun4v_mdesc_init(void) >> >> cur_mdesc = hp; >> >> +#ifdef CONFIG_SPARC64 > > mdesc.c is only built on sparc64, this ifdef is superfluous. > >> +/* Update the state of MCDPER register in current task's mm context before >> + * dup so the dup'd task will inherit flags in this register correctly. >> + * Current task may have updated flags since it started running. >> + */ >> +int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) >> +{ >> + if (adi_capable() && src->mm) { >> + register unsigned long tmp_mcdper; >> + >> + __asm__ __volatile__( >> + ".word 0x83438000\n\t" /* rd %mcdper, %g1 */ >> + "mov %%g1, %0\n\t" >> + : "=r" (tmp_mcdper) >> + : >> + : "g1"); >> + src->mm->context.mcdper = tmp_mcdper; > > I don't like the idea of duplicating 'mm' state using the task struct > copy. Why do not the MM handling interfaces handle this properly? > > Maybe it means you've abstracted the ADI register handling in the > wrong place. Maybe it's a thread property which is "pushed" from > the MM context. > -- > To unsubscribe from this list: send the line "unsubscribe sparclinux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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