From 8eb4bd666ffdca7171cd8118138a91842012b028 Mon Sep 17 00:00:00 2001 From: Michael Holzheu Date: Tue, 10 May 2011 17:13:39 +0200 Subject: [PATCH] [S390] kernel: Initialize register 14 when starting new CPU When starting a new CPU we currently jump to start_secondary() without setting register 14 (the return address) correctly. Therefore on the stack frame for start_secondary an invalid return address is stored. This leads to wrong stack back traces in kernel dumps. Example: #00 [1f33fe48] cpu_idle at 10614a #01 [1f33fe90] start_secondary at 54fa88 #02 [1f33feb8] (null) at 0 <--- invalid To fix this start_secondary() is called now with basr/brasl that sets register 14 correctly. The output of the stack backtrace looks then like the following: #00 [1f33fe48] cpu_idle at 10614a #01 [1f33fe90] start_secondary at 54fa88 #02 [1f33feb8] restart_base at 54f41e <--- correct Signed-off-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/entry.S | 2 +- arch/s390/kernel/entry64.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 648f64239a9d..1b67fc6ebdc2 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -836,7 +836,7 @@ restart_base: stosm __SF_EMPTY(%r15),0x04 # now we can turn dat on basr %r14,0 l %r14,restart_addr-.(%r14) - br %r14 # branch to start_secondary + basr %r14,%r14 # branch to start_secondary restart_addr: .long start_secondary .align 8 diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S index 9d3603d6c511..9fd864563499 100644 --- a/arch/s390/kernel/entry64.S +++ b/arch/s390/kernel/entry64.S @@ -841,7 +841,7 @@ restart_base: mvc __LC_SYSTEM_TIMER(8),__TI_system_timer(%r1) xc __LC_STEAL_TIMER(8),__LC_STEAL_TIMER stosm __SF_EMPTY(%r15),0x04 # now we can turn dat on - jg start_secondary + brasl %r14,start_secondary .align 8 restart_vtime: .long 0x7fffffff,0xffffffff -- 2.20.1