Commit f436b2ac authored by Lorenzo Pieralisi's avatar Lorenzo Pieralisi Committed by Will Deacon
Browse files

arm64: kernel: fix architected PMU registers unconditional access 



The Performance Monitors extension is an optional feature of the
AArch64 architecture, therefore, in order to access Performance
Monitors registers safely, the kernel should detect the architected
PMU unit presence through the ID_AA64DFR0_EL1 register PMUVer field
before accessing them.

This patch implements a guard by reading the ID_AA64DFR0_EL1 register
PMUVer field to detect the architected PMU presence and prevent accessing
PMU system registers if the Performance Monitors extension is not
implemented in the core.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: <stable@vger.kernel.org>
Fixes: 60792ad3 ("arm64: kernel: enforce pmuserenr_el0 initialization and restore")
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reported-by: default avatarGuenter Roeck <linux@roeck-us.net>
Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 7b1af979

arch/arm64/kernel/head.S

+5 −0
Original line number Diff line number Diff line
@@ -514,9 +514,14 @@ CPU_LE( movk x0, #0x30d0, lsl #16 ) // Clear EE and E0E on LE systems 
#endif



	/* EL2 debug */

	mrs	x0, id_aa64dfr0_el1		// Check ID_AA64DFR0_EL1 PMUVer

	sbfx	x0, x0, #8, #4

	cmp	x0, #1

	b.lt	4f				// Skip if no PMU present

	mrs	x0, pmcr_el0			// Disable debug access traps

	ubfx	x0, x0, #11, #5			// to EL2 and allow access to

	msr	mdcr_el2, x0			// all PMU counters from EL1

4:



	/* Stage-2 translation */

	msr	vttbr_el2, xzr

arch/arm64/mm/proc-macros.S

+12 −0
Original line number Diff line number Diff line
@@ -84,3 +84,15 @@ 
	b.lo	9998b

	dsb	\domain

	.endm



/*

 * reset_pmuserenr_el0 - reset PMUSERENR_EL0 if PMUv3 present

 */

	.macro	reset_pmuserenr_el0, tmpreg

	mrs	\tmpreg, id_aa64dfr0_el1	// Check ID_AA64DFR0_EL1 PMUVer

	sbfx	\tmpreg, \tmpreg, #8, #4

	cmp	\tmpreg, #1			// Skip if no PMU present

	b.lt	9000f

	msr	pmuserenr_el0, xzr		// Disable PMU access from EL0

9000:

	.endm

arch/arm64/mm/proc.S

+2 −2
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ ENTRY(cpu_do_resume) 
	 */

	ubfx	x11, x11, #1, #1

	msr	oslar_el1, x11

	msr	pmuserenr_el0, xzr		// Disable PMU access from EL0

	reset_pmuserenr_el0 x0			// Disable PMU access from EL0

	mov	x0, x12

	dsb	nsh		// Make sure local tlb invalidation completed

	isb
@@ -154,7 +154,7 @@ ENTRY(__cpu_setup) 
	msr	cpacr_el1, x0			// Enable FP/ASIMD

	mov	x0, #1 << 12			// Reset mdscr_el1 and disable

	msr	mdscr_el1, x0			// access to the DCC from EL0

	msr	pmuserenr_el0, xzr		// Disable PMU access from EL0

	reset_pmuserenr_el0 x0			// Disable PMU access from EL0

	/*

	 * Memory region attributes for LPAE:

	 *

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