[S390] fix system call parameter functions.

syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 10 insertions, 13 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 41aca06682aa..89c121ae6339 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -46,7 +46,7 @@ SP_R14	     =	STACK_FRAME_OVERHEAD + __PT_GPRS + 112
 SP_R15       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 120
 SP_ORIG_R2   =  STACK_FRAME_OVERHEAD + __PT_ORIG_GPR2
 SP_ILC       =  STACK_FRAME_OVERHEAD + __PT_ILC
-SP_TRAP      =  STACK_FRAME_OVERHEAD + __PT_TRAP
+SP_SVCNR      = STACK_FRAME_OVERHEAD + __PT_SVCNR
 SP_SIZE      =  STACK_FRAME_OVERHEAD + __PT_SIZE
 
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
@@ -171,11 +171,10 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
         .macro  CREATE_STACK_FRAME psworg,savearea
         aghi    %r15,-SP_SIZE           # make room for registers & psw
         mvc     SP_PSW(16,%r15),0(%r12) # move user PSW to stack
-        la      %r12,\psworg
         stg     %r2,SP_ORIG_R2(%r15)    # store original content of gpr 2
-        icm     %r12,12,__LC_SVC_ILC
+        icm     %r12,3,__LC_SVC_ILC
         stmg    %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
-        st      %r12,SP_ILC(%r15)
+        st      %r12,SP_SVCNR(%r15)
         mvc     SP_R12(32,%r15),\savearea # move %r12-%r15 to stack
         la      %r12,0
         stg     %r12,__SF_BACKCHAIN(%r15)
@@ -250,16 +249,17 @@ sysc_update:
 #endif
 sysc_do_svc:
         lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        slag    %r7,%r7,2       # *4 and test for svc 0
+        ltgr    %r7,%r7         # test for svc 0
         jnz     sysc_nr_ok
         # svc 0: system call number in %r1
         cl      %r1,BASED(.Lnr_syscalls)
         jnl     sysc_nr_ok
         lgfr    %r7,%r1         # clear high word in r1
-        slag    %r7,%r7,2       # svc 0: system call number in %r1
 sysc_nr_ok:
         mvc     SP_ARGS(8,%r15),SP_R7(%r15)
 sysc_do_restart:
+        sth     %r7,SP_SVCNR(%r15)
+        sllg    %r7,%r7,2       # svc number * 4
         larl    %r10,sys_call_table
 #ifdef CONFIG_COMPAT
         tm      __TI_flags+5(%r9),(_TIF_31BIT>>16)  # running in 31 bit mode ?
@@ -363,7 +363,6 @@ sysc_notify_resume:
 sysc_restart:
         ni      __TI_flags+7(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
         lg      %r7,SP_R2(%r15)         # load new svc number
-        slag    %r7,%r7,2               # *4
         mvc     SP_R2(8,%r15),SP_ORIG_R2(%r15) # restore first argument
         lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
         j       sysc_do_restart         # restart svc
@@ -372,9 +371,8 @@ sysc_restart:
 # _TIF_SINGLE_STEP is set, call do_single_step
 #
 sysc_singlestep:
-        ni      __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
-        lhi     %r0,__LC_PGM_OLD_PSW
-        sth     %r0,SP_TRAP(%r15)       # set trap indication to pgm check
+        ni      __TI_flags+7(%r9),255-_TIF_SINGLE_STEP  # clear TIF_SINGLE_STEP
+        xc      SP_SVCNR(2,%r15),SP_SVCNR(%r15)         # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         larl    %r14,sysc_return        # load adr. of system return
         jg      do_single_step          # branch to do_sigtrap
@@ -392,7 +390,7 @@ sysc_tracesys:
         lghi    %r0,NR_syscalls
         clgr    %r0,%r2
         jnh     sysc_tracenogo
-        slag    %r7,%r2,2               # *4
+        sllg    %r7,%r2,2               # svc number *4
         lgf     %r8,0(%r7,%r10)
 sysc_tracego:
         lmg     %r3,%r6,SP_R3(%r15)
@@ -567,8 +565,7 @@ pgm_svcper:
 # per was called from kernel, must be kprobes
 #
 kernel_per:
-        lhi     %r0,__LC_PGM_OLD_PSW
-        sth     %r0,SP_TRAP(%r15)       # set trap indication to pgm check
+        xc      SP_SVCNR(2,%r15),SP_SVCNR(%r15) # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         larl    %r14,sysc_restore       # load adr. of system ret, no work
         jg      do_single_step          # branch to do_single_step