[MODERATED] Re: [patch V7 13/15] SBB 13

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

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> PR_SET_SPECULATION_CTRL has these additional return values:
> 
> -ERANGE: arg3 is incorrect, i.e. it's not either PR_SPEC_ENABLE or PR_SPEC_DISABLE

s/not either/neither/

? Feel free to ignore it of course but it read more obvious to me that way.

And also attaching the testing program I spoke off. My previous testing (which
I alluded to in previous emails) missed the obvious case of 'r < 0' meaning
0xfffffff.. which would report that all bits are set (duh).




[-- Attachment #2: test-prctl.c --]
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#include <stdio.h>
       #include <sys/prctl.h>

#define SPEC_CTRL_RDS_SHIFT            2          /* Reduced Data Speculation bit */
/* Per task speculation control */
#define PR_SET_SPECULATION_CTRL                52
#define PR_GET_SPECULATION_CTRL                53
/* Speculation control variants */
# define PR_SPEC_STORE_BYPASS          0
/* Return and control values for PR_SET/GET_SPECULATION_CTRL */
# define PR_SPEC_NOT_AFFECTED          0
# define PR_SPEC_PRCTL                 (1UL << 0)
# define PR_SPEC_ENABLE                        (1UL << 1)
# define PR_SPEC_DISABLE               (1UL << 2)

void print_bitfields(int r)
{
 if ( r >= 0 )
 	fprintf(stderr, "	r=%s %s %s\n", r & PR_SPEC_PRCTL ? "PR_SPEC_PRCTL" : "",
		r & PR_SPEC_ENABLE ? "PR_SPEC_ENABLE" : "",
		r & PR_SPEC_DISABLE ? "PR_SPEC_DISABLE" : "");

}
void get_v(void)
{
 int r;
 r = prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS);
 fprintf(stderr, "   PR_GET_SPECULATION_CTRL PR_SPEC_STORE_BYPASS r=%d\n", r);
 print_bitfields(r);

}

int main(void)
{
 int r;

 fprintf(stderr,"Initial state\n"); 
 get_v();

 r = prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE);
 fprintf(stderr, "PR_SET_SPECULATION_CTRL PR_SPEC_DISABLE r=%d\n", r);
 print_bitfields(r);
 get_v();

 /* Two DISALBE in a row*/
 r = prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE);
 fprintf(stderr, "PR_SET_SPECULATION_CTRL PR_SPEC_DISABLE r=%d\n", r);
 print_bitfields(r);
 get_v();

 /* Two enable in a row. */
 r = prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE);
 fprintf(stderr, "PR_SET_SPECULATION_CTRL PR_SPEC_ENABLE r=%d\n", r);
 print_bitfields(r);
 get_v();

 r = prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE);
 fprintf(stderr, "PR_SET_SPECULATION_CTRL PR_SPEC_ENABLE r=%d\n", r);
 print_bitfields(r);
 get_v();
 fprintf(stderr,"\nReal test-case\n");
 /* The real normal test-case */
 r = prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE);
 fprintf(stderr, "PR_SET_SPECULATION_CTRL PR_SPEC_DISABLE r=%d\n", r);
 print_bitfields(r);
 get_v();

 do { } while (1);
 
	return 0;
}