| From: Michael Neuling <mikey@neuling.org> |
| Date: Fri, 18 May 2018 11:37:42 +1000 |
| Subject: 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: Michael Neuling <mikey@neuling.org> |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| [bwh: Backported to 3.16: Drop changes in __{setup,restore}_cpu_power9 |
| and __restore_cpu_cpufeatures()] |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| --- a/arch/powerpc/kernel/cpu_setup_power.S |
| +++ b/arch/powerpc/kernel/cpu_setup_power.S |
| @@ -27,6 +27,7 @@ _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 |
| @@ -40,6 +41,7 @@ _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 |
| @@ -55,6 +57,7 @@ _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 |
| @@ -74,6 +77,7 @@ _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 |
