On Thu, Sep 28, 2017 at 03:09:49PM +0100, Will Deacon wrote: > When booting at EL2, ensure that we permit the EL1 host to sample > physical addresses and physical counter values using SPE. > > Signed-off-by: Will Deacon <will.dea...@arm.com> > --- > arch/arm64/kernel/head.S | 17 ++++++++++++----- > 1 file changed, 12 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 7434ec0c7a27..c370e270ae55 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -479,14 +479,21 @@ set_hcr: > > /* Statistical profiling */ > ubfx x0, x1, #32, #4 // Check ID_AA64DFR0_EL1 PMSVer > - cbz x0, 6f // Skip if SPE not present > - cbnz x2, 5f // VHE? > + cbz x0, 7f // Skip if SPE not present > + cbnz x2, 6f // VHE? > + mrs_s x4, SYS_PMBIDR_EL1 // If SPE available at EL2, > + and x4, x4, #(1 << SYS_PMBIDR_EL1_P_SHIFT) > + cbnz x4, 5f // then permit sampling of > physical > + mov x4, #(1 << SYS_PMSCR_EL2_PCT_SHIFT | \ > + 1 << SYS_PMSCR_EL2_PA_SHIFT) > + msr_s SYS_PMSCR_EL2, x4 // addresses and physical > counter
As a general note, I find these right-hand-side comments difficult to read, especially here with multiple line gaps mid-sentence. If I'm alone in that view, there's no reason to change them, but otherwise it might make sense to replace the more complex comments with /* */ comment blocks on their own lines... The logic looks fine to me, so FWIW: Acked-by: Mark Rutland <mark.rutl...@arm.com> Mark. > +5: > mov x1, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT) > orr x3, x3, x1 // If we don't have VHE, then > - b 6f // use EL1&0 translation. > -5: // For VHE, use EL2 translation > + b 7f // use EL1&0 translation. > +6: // For VHE, use EL2 translation > orr x3, x3, #MDCR_EL2_TPMS // and disable access from EL1 > -6: > +7: > msr mdcr_el2, x3 // Configure debug traps > > /* Stage-2 translation */ > -- > 2.1.4 >
