diff mbox series

powepc: Clear PCR on boot

Message ID 20180518013742.24095-1-mikey@neuling.org (mailing list archive)
State Accepted
Commit faf37c44a105f3608115785f17cbbf3500f8bc71
Headers show
Series powepc: Clear PCR on boot | expand

Commit Message

Michael Neuling May 18, 2018, 1:37 a.m. UTC 
Clear the PCR on boot to ensure we are not running in a compat 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: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org>
---
 arch/powerpc/kernel/cpu_setup_power.S | 6 ++++++
 arch/powerpc/kernel/dt_cpu_ftrs.c     | 1 +
 2 files changed, 7 insertions(+)

Comments

Michael Ellerman May 21, 2018, 9:55 a.m. UTC | #1 
On Fri, 2018-05-18 at 01:37:42 UTC, Michael Neuling wrote:
> Clear the PCR on boot to ensure we are not running in a compat 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: Michael Neuling <mikey@neuling.org>
> Cc: <stable@vger.kernel.org>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/faf37c44a105f3608115785f17cbbf

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/cpu_setup_power.S b/arch/powerpc/kernel/cpu_setup_power.S
index 3f30c994e9..458b928dbd 100644
--- a/arch/powerpc/kernel/cpu_setup_power.S
+++ b/arch/powerpc/kernel/cpu_setup_power.S
@@ -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
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 8ab51f6ca0..c904477aba 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -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);