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Commit 09ae0d2e authored by Michael Neuling's avatar Michael Neuling Committed by Greg Kroah-Hartman
Browse files

powerpc/64s: Clear PCR on boot 



commit faf37c44a105f3608115785f17cbbf3500f8bc71 upstream.

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>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b27fb13e

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

	bl	__init_LPCR

	bl	__init_tlb_power7
@@ -41,6 +42,7 @@ _GLOBAL(__restore_cpu_power7) 
	beqlr

	li	r0,0

	mtspr	SPRN_LPID,r0

	mtspr	SPRN_PCR,r0

	mfspr	r3,SPRN_LPCR

	bl	__init_LPCR

	bl	__init_tlb_power7
@@ -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

	bl	__init_LPCR
@@ -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

	bl	__init_LPCR
@@ -98,6 +102,7 @@ _GLOBAL(__setup_cpu_power9) 
	li	r0,0

	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)

	or	r3, r3, r4
@@ -121,6 +126,7 @@ _GLOBAL(__restore_cpu_power9) 
	li	r0,0

	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)

	or	r3, r3, r4