linux-kernel - [PATCH 4.16 026/272] powerpc/64s: Clear PCR on boot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180528100242.815290603@linuxfoundation.org>
Date:   Mon, 28 May 2018 12:00:59 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michael Neuling <mikey@...ling.org>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.16 026/272] powerpc/64s: Clear PCR on boot

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Neuling <mikey@...ling.org>

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: Michael Neuling <mikey@...ling.org>
Cc: stable@...r.kernel.org
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/cpu_setup_power.S |    6 ++++++
 arch/powerpc/kernel/dt_cpu_ftrs.c     |    1 +
 2 files changed, 7 insertions(+)

--- 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
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -114,6 +114,7 @@ static void __restore_cpu_cpufeatures(vo
 	if (hv_mode) {
 		mtspr(SPRN_LPID, 0);
 		mtspr(SPRN_HFSCR, system_registers.hfscr);
+		mtspr(SPRN_PCR, 0);
 	}
 	mtspr(SPRN_FSCR, system_registers.fscr);