[PATCH] s390: signals & exceptions.

From: Martin Schwidefsky
Date: Fri Jul 09 2004 - 12:19:31 EST

[PATCH] s390: signals & exceptions.

From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
From: Ulrich Weigand <uweigand@xxxxxxxxxx>

s390 core changes:
- Add signo between signal frame and the signal return instruction on the
user stack for backtrace over signal handlers.
- Add hfp floating point exceptions.
- Use a single function for region, segment and page translation exceptions.
- Discard SIGTRAP for single stepped instructions if the trapping instruction
is repeated (normal memory faults) or if another signal is delivered anyway.

Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

diffstat:
arch/s390/kernel/compat_signal.c | 5 ++
arch/s390/kernel/entry.S | 38 +++++++-----------
arch/s390/kernel/entry64.S | 23 ++++-------
arch/s390/kernel/signal.c | 5 ++
arch/s390/kernel/traps.c | 79 ++++++++++++++++++++++-----------------
arch/s390/mm/fault.c | 40 +++++++++----------
include/asm-s390/thread_info.h | 2
7 files changed, 101 insertions(+), 91 deletions(-)

diff -urN linux-2.6/arch/s390/kernel/compat_signal.c linux-2.6-s390/arch/s390/kernel/compat_signal.c
--- linux-2.6/arch/s390/kernel/compat_signal.c Wed Jun 16 07:20:03 2004
+++ linux-2.6-s390/arch/s390/kernel/compat_signal.c Fri Jul 9 18:58:54 2004
@@ -40,6 +40,7 @@
__u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
struct sigcontext32 sc;
_sigregs32 sregs;
+ int signo;
__u8 retcode[S390_SYSCALL_SIZE];
} sigframe32;

@@ -497,6 +498,10 @@
To avoid breaking binary compatibility, they are passed as args. */
regs->gprs[4] = current->thread.trap_no;
regs->gprs[5] = current->thread.prot_addr;
+
+ /* Place signal number on stack to allow backtrace from handler. */
+ if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
+ goto give_sigsegv;
return;

give_sigsegv:
diff -urN linux-2.6/arch/s390/kernel/entry.S linux-2.6-s390/arch/s390/kernel/entry.S
--- linux-2.6/arch/s390/kernel/entry.S Wed Jun 16 07:19:01 2004
+++ linux-2.6-s390/arch/s390/kernel/entry.S Fri Jul 9 18:58:54 2004
@@ -70,7 +70,7 @@
.macro CLEANUP_SAVE_ALL_BASE psworg,savearea,sync
l %r1,SP_PSW+4(%r15)
cli 1(%r1),0xcf
- jne 0f
+ bne BASED(0f)
mvc \savearea(16),SP_R12(%r15)
0: st %r13,SP_R13(%r15)
.endm
@@ -140,9 +140,9 @@
.macro CLEANUP_RESTORE_ALL
l %r1,SP_PSW+4(%r15)
cli 0(%r1),0x82
- jne 0f
+ bne BASED(0f)
mvc SP_PSW(8,%r15),__LC_RETURN_PSW
- j 1f
+ b BASED(1f)
0: l %r1,SP_R15(%r15)
mvc SP_PSW(8,%r15),SP_PSW(%r1)
mvc SP_R0(64,%r15),SP_R0(%r1)
@@ -157,9 +157,9 @@
tm SP_PSW+1(%r15),0x01 # test problem state bit
bnz BASED(0f) # from user -> not critical
clc SP_PSW+4(4,%r15),BASED(.Lcritical_end)
- jnl 0f
+ bnl BASED(0f)
clc SP_PSW+4(4,%r15),BASED(.Lcritical_start)
- jl 0f
+ bl BASED(0f)
l %r1,BASED(.Lcleanup_critical)
basr %r14,%r1
0:
@@ -291,6 +291,7 @@
# _TIF_SIGPENDING is set, call do_signal
#
sysc_sigpending:
+ ni __TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
la %r2,SP_PTREGS(%r15) # load pt_regs
sr %r3,%r3 # clear *oldset
l %r1,BASED(.Ldo_signal)
@@ -311,7 +312,7 @@
b BASED(sysc_do_restart) # restart svc

#
-# _TIF_SINGLE_STEP is set, call do_debugger_trap
+# _TIF_SINGLE_STEP is set, call do_single_step
#
sysc_singlestep:
ni __TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
@@ -319,7 +320,7 @@
la %r2,SP_PTREGS(%r15) # address of register-save area
l %r1,BASED(.Lhandle_per) # load adr. of per handler
la %r14,BASED(sysc_return) # load adr. of system return
- br %r1 # branch to do_debugger_trap
+ br %r1 # branch to do_single_step

__critical_end:

@@ -460,8 +461,9 @@
SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1
l %r3,__LC_PGM_ILC # load program interruption code
la %r8,0x7f
- l %r7,BASED(.Ljump_table)
nr %r8,%r3
+pgm_do_call:
+ l %r7,BASED(.Ljump_table)
sll %r8,2
GET_THREAD_INFO
l %r7,0(%r8,%r7) # load address of handler routine
@@ -492,20 +494,12 @@
mvc __THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
mvc __THREAD_per+__PER_address(4,%r1),__LC_PER_ADDRESS
mvc __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
- la %r4,0x7f
+ oi __TI_flags+3(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
l %r3,__LC_PGM_ILC # load program interruption code
- nr %r4,%r3 # clear per-event-bit and ilc
- be BASED(pgm_per_only) # only per or per+check ?
- l %r1,BASED(.Ljump_table)
- sll %r4,2
- l %r1,0(%r4,%r1) # load address of handler routine
- la %r2,SP_PTREGS(%r15) # address of register-save area
- basr %r14,%r1 # branch to interrupt-handler
-pgm_per_only:
- la %r2,SP_PTREGS(15) # address of register-save area
- l %r1,BASED(.Lhandle_per) # load adr. of per handler
- la %r14,BASED(sysc_return) # load adr. of system return
- br %r1 # branch to do_debugger_trap
+ la %r8,0x7f
+ nr %r8,%r3 # clear per-event-bit and ilc
+ be BASED(sysc_return) # only per or per+check ?
+ b BASED(pgm_do_call)

#
# it was a single stepped SVC that is causing all the trouble
@@ -745,7 +739,7 @@
.Ldo_extint: .long do_extint
.Ldo_signal: .long do_signal
.Ldo_softirq: .long do_softirq
-.Lhandle_per: .long do_debugger_trap
+.Lhandle_per: .long do_single_step
.Ljump_table: .long pgm_check_table
.Lschedule: .long schedule
.Lclone: .long sys_clone
diff -urN linux-2.6/arch/s390/kernel/entry64.S linux-2.6-s390/arch/s390/kernel/entry64.S
--- linux-2.6/arch/s390/kernel/entry64.S Fri Jul 9 18:58:41 2004
+++ linux-2.6-s390/arch/s390/kernel/entry64.S Fri Jul 9 18:58:54 2004
@@ -282,6 +282,7 @@
# _TIF_SIGPENDING is set, call do_signal
#
sysc_sigpending:
+ ni __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
la %r2,SP_PTREGS(%r15) # load pt_regs
sgr %r3,%r3 # clear *oldset
brasl %r14,do_signal # call do_signal
@@ -301,7 +302,7 @@
j sysc_do_restart # restart svc

#
-# _TIF_SINGLE_STEP is set, call do_debugger_trap
+# _TIF_SINGLE_STEP is set, call do_single_step
#
sysc_singlestep:
ni __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
@@ -309,7 +310,7 @@
sth %r0,SP_TRAP(%r15) # set trap indication to pgm check
la %r2,SP_PTREGS(%r15) # address of register-save area
larl %r14,sysc_return # load adr. of system return
- jg do_debugger_trap # branch to do_debugger_trap
+ jg do_single_step # branch to do_sigtrap


__critical_end:
@@ -497,6 +498,7 @@
lgf %r3,__LC_PGM_ILC # load program interruption code
lghi %r8,0x7f
ngr %r8,%r3
+pgm_do_call:
sll %r8,3
GET_THREAD_INFO
larl %r1,pgm_check_table
@@ -527,19 +529,12 @@
mvc __THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
mvc __THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
mvc __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
- lghi %r4,0x7f
+ oi __TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
lgf %r3,__LC_PGM_ILC # load program interruption code
- nr %r4,%r3 # clear per-event-bit and ilc
- je pgm_per_only # only per of per+check ?
- sll %r4,3
- larl %r1,pgm_check_table
- lg %r1,0(%r4,%r1) # load address of handler routine
- la %r2,SP_PTREGS(%r15) # address of register-save area
- basr %r14,%r1 # branch to interrupt-handler
-pgm_per_only:
- la %r2,SP_PTREGS(15) # address of register-save area
- larl %r14,sysc_return # load adr. of system return
- jg do_debugger_trap
+ lghi %r8,0x7f
+ ngr %r8,%r3 # clear per-event-bit and ilc
+ je sysc_return
+ j pgm_do_call

#
# it was a single stepped SVC that is causing all the trouble
diff -urN linux-2.6/arch/s390/kernel/signal.c linux-2.6-s390/arch/s390/kernel/signal.c
--- linux-2.6/arch/s390/kernel/signal.c Wed Jun 16 07:19:44 2004
+++ linux-2.6-s390/arch/s390/kernel/signal.c Fri Jul 9 18:58:54 2004
@@ -39,6 +39,7 @@
__u8 callee_used_stack[__SIGNAL_FRAMESIZE];
struct sigcontext sc;
_sigregs sregs;
+ int signo;
__u8 retcode[S390_SYSCALL_SIZE];
} sigframe;

@@ -350,6 +351,10 @@
To avoid breaking binary compatibility, they are passed as args. */
regs->gprs[4] = current->thread.trap_no;
regs->gprs[5] = current->thread.prot_addr;
+
+ /* Place signal number on stack to allow backtrace from handler. */
+ if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
+ goto give_sigsegv;
return;

give_sigsegv:
diff -urN linux-2.6/arch/s390/kernel/traps.c linux-2.6-s390/arch/s390/kernel/traps.c
--- linux-2.6/arch/s390/kernel/traps.c Fri Jul 9 18:58:41 2004
+++ linux-2.6-s390/arch/s390/kernel/traps.c Fri Jul 9 18:58:54 2004
@@ -54,9 +54,7 @@
#endif

extern pgm_check_handler_t do_protection_exception;
-extern pgm_check_handler_t do_segment_exception;
-extern pgm_check_handler_t do_region_exception;
-extern pgm_check_handler_t do_page_exception;
+extern pgm_check_handler_t do_dat_exception;
extern pgm_check_handler_t do_pseudo_page_fault;
#ifdef CONFIG_PFAULT
extern int pfault_init(void);
@@ -300,14 +298,10 @@
return (void *)((regs->psw.addr-S390_lowcore.pgm_ilc) & PSW_ADDR_INSN);
}

-int do_debugger_trap(struct pt_regs *regs)
+void do_single_step(struct pt_regs *regs)
{
- if ((regs->psw.mask & PSW_MASK_PSTATE) &&
- (current->ptrace & PT_PTRACED)) {
- force_sig(SIGTRAP,current);
- return 0;
- }
- return 1;
+ if ((current->ptrace & PT_PTRACED) != 0)
+ force_sig(SIGTRAP, current);
}

#define DO_ERROR(signr, str, name) \
@@ -329,12 +323,24 @@

DO_ERROR(SIGSEGV, "Unknown program exception", default_trap_handler)

-DO_ERROR_INFO(SIGBUS, "addressing exception", addressing_exception,
- BUS_ADRERR, get_check_address(regs))
+DO_ERROR_INFO(SIGILL, "addressing exception", addressing_exception,
+ ILL_ILLADR, get_check_address(regs))
DO_ERROR_INFO(SIGILL, "execute exception", execute_exception,
ILL_ILLOPN, get_check_address(regs))
DO_ERROR_INFO(SIGFPE, "fixpoint divide exception", divide_exception,
FPE_INTDIV, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "fixpoint overflow exception", overflow_exception,
+ FPE_INTOVF, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "HFP overflow exception", hfp_overflow_exception,
+ FPE_FLTOVF, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "HFP underflow exception", hfp_underflow_exception,
+ FPE_FLTUND, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "HFP significance exception", hfp_significance_exception,
+ FPE_FLTRES, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "HFP divide exception", hfp_divide_exception,
+ FPE_FLTDIV, get_check_address(regs))
+DO_ERROR_INFO(SIGFPE, "HFP square root exception", hfp_sqrt_exception,
+ FPE_FLTINV, get_check_address(regs))
DO_ERROR_INFO(SIGILL, "operand exception", operand_exception,
ILL_ILLOPN, get_check_address(regs))
DO_ERROR_INFO(SIGILL, "privileged operation", privileged_op,
@@ -388,19 +394,15 @@
if (regs->psw.mask & PSW_MASK_PSTATE)
local_irq_enable();

- if (regs->psw.mask & PSW_MASK_PSTATE)
- get_user(*((__u16 *) opcode), (__u16 __user *)location);
- else
- *((__u16 *)opcode)=*((__u16 *)location);
- if (*((__u16 *)opcode)==S390_BREAKPOINT_U16)
- {
- if(do_debugger_trap(regs))
- signal = SIGILL;
- }
+ if (regs->psw.mask & PSW_MASK_PSTATE) {
+ get_user(*((__u16 *) opcode), (__u16 __user *) location);
+ if (*((__u16 *) opcode) == S390_BREAKPOINT_U16) {
+ if (current->ptrace & PT_PTRACED)
+ force_sig(SIGTRAP, current);
+ else
+ signal = SIGILL;
#ifdef CONFIG_MATHEMU
- else if (regs->psw.mask & PSW_MASK_PSTATE)
- {
- if (opcode[0] == 0xb3) {
+ } else if (opcode[0] == 0xb3) {
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_b3(opcode, regs);
} else if (opcode[0] == 0xed) {
@@ -416,12 +418,12 @@
} else if (*((__u16 *) opcode) == 0xb29d) {
get_user(*((__u16 *) (opcode+2)), location+1);
signal = math_emu_lfpc(opcode, regs);
+#endif
} else
signal = SIGILL;
- }
-#endif
- else
+ } else
signal = SIGILL;
+
if (signal == SIGFPE)
do_fp_trap(regs, location,
current->thread.fp_regs.fpc, interruption_code);
@@ -445,9 +447,9 @@
* We got all needed information from the lowcore and can
* now safely switch on interrupts.
*/
- if (regs->psw.mask & PSW_MASK_PSTATE)
+ if (regs->psw.mask & PSW_MASK_PSTATE)
local_irq_enable();
-
+
if (regs->psw.mask & PSW_MASK_PSTATE) {
get_user(*((__u16 *) opcode), location);
switch (opcode[0]) {
@@ -479,6 +481,7 @@
}
} else
signal = SIGILL;
+
if (signal == SIGFPE)
do_fp_trap(regs, location,
current->thread.fp_regs.fpc, interruption_code);
@@ -605,19 +608,29 @@
pgm_check_table[5] = &addressing_exception;
pgm_check_table[6] = &specification_exception;
pgm_check_table[7] = &data_exception;
+ pgm_check_table[8] = &overflow_exception;
pgm_check_table[9] = &divide_exception;
- pgm_check_table[0x10] = &do_segment_exception;
- pgm_check_table[0x11] = &do_page_exception;
+ pgm_check_table[0x0A] = &overflow_exception;
+ pgm_check_table[0x0B] = &divide_exception;
+ pgm_check_table[0x0C] = &hfp_overflow_exception;
+ pgm_check_table[0x0D] = &hfp_underflow_exception;
+ pgm_check_table[0x0E] = &hfp_significance_exception;
+ pgm_check_table[0x0F] = &hfp_divide_exception;
+ pgm_check_table[0x10] = &do_dat_exception;
+ pgm_check_table[0x11] = &do_dat_exception;
pgm_check_table[0x12] = &translation_exception;
pgm_check_table[0x13] = &special_op_exception;
#ifndef CONFIG_ARCH_S390X
pgm_check_table[0x14] = &do_pseudo_page_fault;
#else /* CONFIG_ARCH_S390X */
- pgm_check_table[0x38] = &addressing_exception;
- pgm_check_table[0x3B] = &do_region_exception;
+ pgm_check_table[0x38] = &do_dat_exception;
+ pgm_check_table[0x39] = &do_dat_exception;
+ pgm_check_table[0x3A] = &do_dat_exception;
+ pgm_check_table[0x3B] = &do_dat_exception;
#endif /* CONFIG_ARCH_S390X */
pgm_check_table[0x15] = &operand_exception;
pgm_check_table[0x1C] = &privileged_op;
+ pgm_check_table[0x1D] = &hfp_sqrt_exception;
pgm_check_table[0x40] = &do_monitor_call;

if (MACHINE_IS_VM) {
diff -urN linux-2.6/arch/s390/mm/fault.c linux-2.6-s390/arch/s390/mm/fault.c
--- linux-2.6/arch/s390/mm/fault.c Wed Jun 16 07:19:44 2004
+++ linux-2.6-s390/arch/s390/mm/fault.c Fri Jul 9 18:58:54 2004
@@ -159,7 +159,8 @@
* 11 Page translation -> Not present (nullification)
* 3b Region third trans. -> Not present (nullification)
*/
-extern inline void do_exception(struct pt_regs *regs, unsigned long error_code)
+extern inline void
+do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection)
{
struct task_struct *tsk;
struct mm_struct *mm;
@@ -177,7 +178,7 @@
* as a special case because the translation exception code
* field is not guaranteed to contain valid data in this case.
*/
- if (error_code == 4 && !(S390_lowcore.trans_exc_code & 4)) {
+ if (is_protection && !(S390_lowcore.trans_exc_code & 4)) {

/* Low-address protection hit in kernel mode means
NULL pointer write access in kernel mode. */
@@ -232,7 +233,7 @@
*/
good_area:
si_code = SEGV_ACCERR;
- if (error_code != 4) {
+ if (!is_protection) {
/* page not present, check vm flags */
if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
goto bad_area;
@@ -247,7 +248,7 @@
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- switch (handle_mm_fault(mm, vma, address, error_code == 4)) {
+ switch (handle_mm_fault(mm, vma, address, is_protection)) {
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
@@ -263,6 +264,11 @@
}

up_read(&mm->mmap_sem);
+ /*
+ * The instruction that caused the program check will
+ * be repeated. Don't signal single step via SIGTRAP.
+ */
+ clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
return;

/*
@@ -337,28 +343,15 @@
void do_protection_exception(struct pt_regs *regs, unsigned long error_code)
{
regs->psw.addr -= (error_code >> 16);
- do_exception(regs, 4);
-}
-
-void do_segment_exception(struct pt_regs *regs, unsigned long error_code)
-{
- do_exception(regs, 0x10);
+ do_exception(regs, 4, 1);
}

-void do_page_exception(struct pt_regs *regs, unsigned long error_code)
-{
- do_exception(regs, 0x11);
-}
-
-#ifdef CONFIG_ARCH_S390X
-
-void
-do_region_exception(struct pt_regs *regs, unsigned long error_code)
+void do_dat_exception(struct pt_regs *regs, unsigned long error_code)
{
- do_exception(regs, 0x3b);
+ do_exception(regs, error_code & 0xff, 0);
}

-#else /* CONFIG_ARCH_S390X */
+#ifndef CONFIG_ARCH_S390X

typedef struct _pseudo_wait_t {
struct _pseudo_wait_t *next;
@@ -456,6 +449,11 @@
wait_struct.next = pseudo_lock_queue;
pseudo_lock_queue = &wait_struct;
spin_unlock(&pseudo_wait_spinlock);
+ /*
+ * The instruction that caused the program check will
+ * be repeated. Don't signal single step via SIGTRAP.
+ */
+ clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
/* go to sleep */
wait_event(wait_struct.queue, wait_struct.resolved);
}
diff -urN linux-2.6/include/asm-s390/thread_info.h linux-2.6-s390/include/asm-s390/thread_info.h
--- linux-2.6/include/asm-s390/thread_info.h Wed Jun 16 07:19:42 2004
+++ linux-2.6-s390/include/asm-s390/thread_info.h Fri Jul 9 18:58:54 2004
@@ -85,7 +85,7 @@
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTART_SVC 4 /* restart svc with new svc number */
#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
-#define TIF_SINGLE_STEP 6 /* single stepped svc */
+#define TIF_SINGLE_STEP 6 /* deliver sigtrap on return to user */
#define TIF_USEDFPU 16 /* FPU was used by this task this quantum (SMP) */
#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling
TIF_NEED_RESCHED */
-
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