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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2013-02-28 16:28:41 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-20 13:10:56 -0700 |
| commit | 49f3b963417563122962c47d359349a2e5b497a3 (patch) | |
| tree | 31553204e1c72db7cd04dadff16c25dd866d5c44 | |
| parent | 4dea73c2050856c498672b0f2f8e07287e1f773d (diff) | |
| download | lwn-49f3b963417563122962c47d359349a2e5b497a3.tar.gz lwn-49f3b963417563122962c47d359349a2e5b497a3.zip | |
s390: critical section cleanup vs. machine checks
commit 6551fbdfd8b85d1ab5822ac98abb4fb449bcfae0 upstream.
The current machine check code uses the registers stored by the machine
in the lowcore at __LC_GPREGS_SAVE_AREA as the registers of the interrupted
context. The registers 0-7 of a user process can get clobbered if a machine
checks interrupts the execution of a critical section in entry[64].S.
The reason is that the critical section cleanup code may need to modify
the PSW and the registers for the previous context to get to the end of a
critical section. If registers 0-7 have to be replaced the relevant copy
will be in the registers, which invalidates the copy in the lowcore. The
machine check handler needs to explicitly store registers 0-7 to the stack.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/kernel/entry.S | 3 | ||||
| -rw-r--r-- | arch/s390/kernel/entry64.S | 5 |
2 files changed, 5 insertions, 3 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 550228523267..94feff7d6132 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -636,7 +636,8 @@ ENTRY(mcck_int_handler) UPDATE_VTIME %r14,%r15,__LC_MCCK_ENTER_TIMER mcck_skip: SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+32,__LC_PANIC_STACK,PAGE_SHIFT - mvc __PT_R0(64,%r11),__LC_GPREGS_SAVE_AREA + stm %r0,%r7,__PT_R0(%r11) + mvc __PT_R8(32,%r11),__LC_GPREGS_SAVE_AREA+32 stm %r8,%r9,__PT_PSW(%r11) xc __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15) l %r1,BASED(.Ldo_machine_check) diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S index 6d34e0c97a39..082b845ed8d7 100644 --- a/arch/s390/kernel/entry64.S +++ b/arch/s390/kernel/entry64.S @@ -678,8 +678,9 @@ ENTRY(mcck_int_handler) UPDATE_VTIME %r14,__LC_MCCK_ENTER_TIMER LAST_BREAK %r14 mcck_skip: - lghi %r14,__LC_GPREGS_SAVE_AREA - mvc __PT_R0(128,%r11),0(%r14) + lghi %r14,__LC_GPREGS_SAVE_AREA+64 + stmg %r0,%r7,__PT_R0(%r11) + mvc __PT_R8(64,%r11),0(%r14) stmg %r8,%r9,__PT_PSW(%r11) xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) lgr %r2,%r11 # pass pointer to pt_regs |