[PATCH] 2.5.41 s390 (/8): syscall tracing.

From: Martin Schwidefsky (schwidefsky@de.ibm.com)
Date: Wed Oct 09 2002 - 07:31:09 EST


Pass the system call number in grp2 to strace instead of -ENOSYS.

diff -urN linux-2.5.41/arch/s390/kernel/entry.S linux-2.5.41-s390/arch/s390/kernel/entry.S
--- linux-2.5.41/arch/s390/kernel/entry.S Wed Oct 9 14:01:13 2002
+++ linux-2.5.41-s390/arch/s390/kernel/entry.S Wed Oct 9 14:01:41 2002
@@ -177,11 +177,11 @@
 system_call:
         SAVE_ALL_BASE
         SAVE_ALL __LC_SVC_OLD_PSW,1
- lh %r8,0x8a # get svc number from lowcore
- sll %r8,2
+ lh %r7,0x8a # get svc number from lowcore
         GET_THREAD_INFO # load pointer to task_struct to R9
+ sll %r7,2
         stosm 24(%r15),0x03 # reenable interrupts
- l %r8,sys_call_table-entry_base(%r8,%r13) # get system call addr.
+ l %r8,sys_call_table-entry_base(%r7,%r13) # get system call addr.
         tm __TI_flags+3(%r9),_TIF_SYSCALL_TRACE
         bo BASED(sysc_tracesys)
         basr %r14,%r8 # call sys_xxxx
@@ -241,13 +241,13 @@
 #
 sysc_tracesys:
         l %r1,BASED(.Ltrace)
- mvc SP_R2(4,%r15),BASED(.Lc_ENOSYS)
+ srl %r7,2
+ st %r7,SP_R2(4,%r15)
         basr %r14,%r1
- clc SP_R2(4,%r15),BASED(.Lc256)
- bnl BASED(sysc_tracego)
- l %r8,SP_R2(%r15) # strace changed the syscall
- sll %r8,2
- l %r8,sys_call_table-entry_base(%r8,%r13)
+ l %r7,SP_R2(4,%r15) # strace might have changed the
+ n %r7,BASED(.Lc256) # system call
+ sll %r7,2
+ l %r8,sys_call_table-entry_base(%r7,%r13)
 sysc_tracego:
         lm %r3,%r6,SP_R3(%r15)
         l %r2,SP_ORIG_R2(%r15)
diff -urN linux-2.5.41/arch/s390x/kernel/entry.S linux-2.5.41-s390/arch/s390x/kernel/entry.S
--- linux-2.5.41/arch/s390x/kernel/entry.S Wed Oct 9 14:01:13 2002
+++ linux-2.5.41-s390/arch/s390x/kernel/entry.S Wed Oct 9 14:01:41 2002
@@ -158,16 +158,16 @@
         .globl system_call
 system_call:
         SAVE_ALL __LC_SVC_OLD_PSW,1
- llgh %r8,__LC_SVC_INT_CODE # get svc number from lowcore
+ llgh %r7,__LC_SVC_INT_CODE # get svc number from lowcore
         GET_THREAD_INFO # load pointer to task_struct to R9
         stosm 48(%r15),0x03 # reenable interrupts
- larl %r7,sys_call_table
- sll %r8,3
+ larl %r10,sys_call_table
+ sll %r7,3
         tm SP_PSW+3(%r15),0x01 # are we running in 31 bit mode ?
         jo sysc_noemu
- la %r7,4(%r7) # use 31 bit emulation system calls
+ la %r10,4(%r10) # use 31 bit emulation system calls
 sysc_noemu:
- lgf %r8,0(%r8,%r7) # load address of system call routine
+ lgf %r8,0(%r7,%r10) # load address of system call routine
         tm __TI_flags+7(%r9),_TIF_SYSCALL_TRACE
         jo sysc_tracesys
         basr %r14,%r8 # call sys_xxxx
@@ -225,15 +225,13 @@
 # special linkage: %r12 contains the return address for trace_svc
 #
 sysc_tracesys:
- lghi %r0,-ENOSYS
- stg %r0,SP_R2(%r15) # give sysc_trace an -ENOSYS retval
+ srl %r7,3
+ stg %r7,SP_R2(%r15)
         brasl %r14,syscall_trace
- larl %r6,.Lc256
- clc SP_R2(8,%r15),0(%r6)
- jnl sysc_tracego
- lg %r2,SP_R2(%r15)
- sllg %r2,%r2,3 # strace wants to change the syscall
- lgf %r8,0(%r2,%r7)
+ lghi %r7,255 # strace might have changed the
+ ng %r7,SP_R2(%r15) # the system call
+ sll %r7,3
+ lgf %r8,0(%r7,%r10)
 sysc_tracego:
         lmg %r3,%r6,SP_R3(%r15)
         lg %r2,SP_ORIG_R2(%r15)

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