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Commit faf37c44 authored by Michael Neuling's avatar Michael Neuling Committed by Michael Ellerman
Browse files

powerpc/64s: Clear PCR on boot 



Clear the PCR (Processor Compatibility Register) on boot to ensure we
are not running in a compatibility mode.

We've seen this cause problems when a crash (and kdump) occurs while
running compat mode guests. The kdump kernel then runs with the PCR
set and causes problems. The symptom in the kdump kernel (also seen in
petitboot after fast-reboot) is early userspace programs taking
sigills on newer instructions (seen in libc).

Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c1d2a313

arch/powerpc/kernel/cpu_setup_power.S

+6 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ _GLOBAL(__setup_cpu_power7) 
	beqlr

	li	r0,0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PCR,r0

	mfspr	r3,SPRN_LPCR

	li	r4,(LPCR_LPES1 >> LPCR_LPES_SH)

	bl	__init_LPCR_ISA206
@@ -41,6 +42,7 @@ _GLOBAL(__restore_cpu_power7) 
	beqlr

	li	r0,0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PCR,r0

	mfspr	r3,SPRN_LPCR

	li	r4,(LPCR_LPES1 >> LPCR_LPES_SH)

	bl	__init_LPCR_ISA206
@@ -57,6 +59,7 @@ _GLOBAL(__setup_cpu_power8) 
	beqlr

	li	r0,0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PCR,r0

	mfspr	r3,SPRN_LPCR

	ori	r3, r3, LPCR_PECEDH

	li	r4,0 /* LPES = 0 */
@@ -78,6 +81,7 @@ _GLOBAL(__restore_cpu_power8) 
	beqlr

	li	r0,0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PCR,r0

	mfspr   r3,SPRN_LPCR

	ori	r3, r3, LPCR_PECEDH

	li	r4,0 /* LPES = 0 */
@@ -99,6 +103,7 @@ _GLOBAL(__setup_cpu_power9) 
	mtspr	SPRN_PSSCR,r0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PID,r0

	mtspr	SPRN_PCR,r0

	mfspr	r3,SPRN_LPCR

	LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE  | LPCR_HEIC)

	or	r3, r3, r4
@@ -123,6 +128,7 @@ _GLOBAL(__restore_cpu_power9) 
	mtspr	SPRN_PSSCR,r0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PID,r0

	mtspr	SPRN_PCR,r0

	mfspr   r3,SPRN_LPCR

	LOAD_REG_IMMEDIATE(r4, LPCR_PECEDH | LPCR_PECE_HVEE | LPCR_HVICE | LPCR_HEIC)

	or	r3, r3, r4

arch/powerpc/kernel/dt_cpu_ftrs.c

+1 −0
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ static void __restore_cpu_cpufeatures(void) 
	if (hv_mode) {

		mtspr(SPRN_LPID, 0);

		mtspr(SPRN_HFSCR, system_registers.hfscr);

		mtspr(SPRN_PCR, 0);

	}

	mtspr(SPRN_FSCR, system_registers.fscr);