Return EOPNOTSUPP instead of EINVAL if a PMC allocation request

specifies a PMC capability (e.g., sampling) that is not supported
by hardware.  Return EINVAL early if the PMC class passed in is
not recognized.

MFC after:	3 days

1 files changed, 15 insertions, 1 deletions

diff --git a/sys/dev/hwpmc/hwpmc_mod.c b/sys/dev/hwpmc/hwpmc_mod.c
index 5ba6a44..ecd83d2 100644
--- a/sys/dev/hwpmc/hwpmc_mod.c
+++ b/sys/dev/hwpmc/hwpmc_mod.c
@@ -2790,10 +2790,24 @@ pmc_syscall_handler(struct thread *td, void *syscall_args)
 		 * All sampling mode PMCs need to be able to interrupt the
 		 * CPU.
 		 */
-
 		if (PMC_IS_SAMPLING_MODE(mode))
 			caps |= PMC_CAP_INTERRUPT;
 
+		/* A valid class specifier should have been passed in. */
+		for (n = 0; n < md->pmd_nclass; n++)
+			if (md->pmd_classes[n].pm_class == pa.pm_class)
+				break;
+		if (n == md->pmd_nclass) {
+			error = EINVAL;
+			break;
+		}
+
+		/* The requested PMC capabilities should be feasible. */
+		if ((md->pmd_classes[n].pm_caps & caps) != caps) {
+			error = EOPNOTSUPP;
+			break;
+		}
+
 		PMCDBG(PMC,ALL,2, "event=%d caps=0x%x mode=%d cpu=%d",
 		    pa.pm_ev, caps, mode, cpu);