s390/base: pass pt_regs to early program check handler

Pass pt_regs to early program check handler like it is done for every
other interrupt and exception handler.

Also the passed pt_regs can be changed by the called function and the
changes register contents and psw contents will be taken into account
when returning. In addition the return psw will not be copied to the
program check old psw in lowcore, but to the usual return psw
location, like it is also done by the regular program check handler.
This allows also to get rid of the code that disabled lowcore
protection when changing the return address.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 8fd9772..022cf09 100644 (file)
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -313,7 +313,7 @@ static __always_inline void __noreturn disabled_wait(void)
  * Basic Program Check Handler.
  */
 extern void s390_base_pgm_handler(void);
-extern void (*s390_base_pgm_handler_fn)(void);
+extern void (*s390_base_pgm_handler_fn)(struct pt_regs *regs);
 
 #define ARCH_LOW_ADDRESS_LIMIT 0x7fffffffUL
 

diff --git a/arch/s390/kernel/base.S b/arch/s390/kernel/base.S
index f7fe403..172c23c 100644 (file)
--- a/arch/s390/kernel/base.S
+++ b/arch/s390/kernel/base.S
@@ -14,18 +14,28 @@
        GEN_BR_THUNK %r9
        GEN_BR_THUNK %r14
 
+__PT_R0 = __PT_GPRS
+__PT_R8 = __PT_GPRS + 64
+
 ENTRY(s390_base_pgm_handler)
-       stmg    %r0,%r15,__LC_SAVE_AREA_SYNC
-       basr    %r13,0
-0:     aghi    %r15,-STACK_FRAME_OVERHEAD
+       stmg    %r8,%r15,__LC_SAVE_AREA_SYNC
+       aghi    %r15,-(STACK_FRAME_OVERHEAD+__PT_SIZE)
+       la      %r11,STACK_FRAME_OVERHEAD(%r15)
+       xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+       stmg    %r0,%r7,__PT_R0(%r11)
+       mvc     __PT_PSW(16,%r11),__LC_PGM_OLD_PSW
+       mvc     __PT_R8(64,%r11),__LC_SAVE_AREA_SYNC
+       lgr     %r2,%r11
        larl    %r1,s390_base_pgm_handler_fn
        lg      %r9,0(%r1)
        ltgr    %r9,%r9
        jz      1f
        BASR_EX %r14,%r9
-       lmg     %r0,%r15,__LC_SAVE_AREA_SYNC
-       lpswe   __LC_PGM_OLD_PSW
-1:     lpswe   disabled_wait_psw-0b(%r13)
+       mvc     __LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
+       lmg     %r0,%r15,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
+       lpswe   __LC_RETURN_PSW
+1:     larl    %r13,disabled_wait_psw
+       lpswe   0(%r13)
 ENDPROC(s390_base_pgm_handler)
 
        .align  8

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 9d15180..5715d1a 100644 (file)
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -149,22 +149,14 @@ static __init void setup_topology(void)
        topology_max_mnest = max_mnest;
 }
 
-static void early_pgm_check_handler(void)
+static void early_pgm_check_handler(struct pt_regs *regs)
 {
        const struct exception_table_entry *fixup;
-       unsigned long cr0, cr0_new;
-       unsigned long addr;
 
-       addr = S390_lowcore.program_old_psw.addr;
-       fixup = s390_search_extables(addr);
+       fixup = s390_search_extables(regs->psw.addr);
        if (!fixup)
                disabled_wait();
-       /* Disable low address protection before storing into lowcore. */
-       __ctl_store(cr0, 0, 0);
-       cr0_new = cr0 & ~(1UL << 28);
-       __ctl_load(cr0_new, 0, 0);
-       S390_lowcore.program_old_psw.addr = extable_fixup(fixup);
-       __ctl_load(cr0, 0, 0);
+       regs->psw.addr = extable_fixup(fixup);
 }
 
 static noinline __init void setup_lowcore_early(void)