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Date: Fri, 07 Nov 2008 16:32:33 +0100
From: Martin Schwidefsky <schwidefsky@...ibm.com>
To: David Smith <dsmith@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
Heiko Carstens <heiko.carstens@...ibm.com>
Subject: Re: [patch 15/21] ptrace changes
On Thu, 2008-11-06 at 12:24 -0600, David Smith wrote:
> But, collect_syscall() also calls syscall_get_nr():
>
> *callno = syscall_get_nr(target, regs);
> if (*callno != -1L && maxargs > 0)
> syscall_get_arguments(target, regs, 0, maxargs, args);
>
> Both syscall_get_nr() *and* syscall_get_arguments() returning gprs[2]
> can't be right, can it?
Ok, I managed to get syscall_get_nr() independent from
do_syscall_trace_enter. With the patch below syscall_get_nr() can now be
called anytime for a speeling process.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
---
Subject: [PATCH] fix syscall_get_nr.
From: Martin Schwidefsky <schwidefsky@...ibm.com>
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.
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
arch/s390/include/asm/ptrace.h | 2 +-
arch/s390/include/asm/syscall.h | 4 +---
arch/s390/kernel/asm-offsets.c | 2 +-
arch/s390/kernel/compat_signal.c | 2 +-
arch/s390/kernel/entry.S | 21 +++++++++++----------
arch/s390/kernel/entry64.S | 23 ++++++++++-------------
arch/s390/kernel/ptrace.c | 2 +-
arch/s390/kernel/signal.c | 6 +++---
8 files changed, 29 insertions(+), 33 deletions(-)
diff -urpN linux-2.6/arch/s390/include/asm/ptrace.h linux-2.6-patched/arch/s390/include/asm/ptrace.h
--- linux-2.6/arch/s390/include/asm/ptrace.h 2008-11-07 16:35:54.000000000 +0100
+++ linux-2.6-patched/arch/s390/include/asm/ptrace.h 2008-11-07 16:36:20.000000000 +0100
@@ -321,8 +321,8 @@ struct pt_regs
psw_t psw;
unsigned long gprs[NUM_GPRS];
unsigned long orig_gpr2;
+ unsigned short svcnr;
unsigned short ilc;
- unsigned short trap;
};
#endif
diff -urpN linux-2.6/arch/s390/include/asm/syscall.h linux-2.6-patched/arch/s390/include/asm/syscall.h
--- linux-2.6/arch/s390/include/asm/syscall.h 2008-11-07 16:35:54.000000000 +0100
+++ linux-2.6-patched/arch/s390/include/asm/syscall.h 2008-11-07 16:36:20.000000000 +0100
@@ -17,9 +17,7 @@
static inline long syscall_get_nr(struct task_struct *task,
struct pt_regs *regs)
{
- if (regs->trap != __LC_SVC_OLD_PSW)
- return -1;
- return regs->gprs[2];
+ return regs->svcnr ? regs->svcnr : -1;
}
static inline void syscall_rollback(struct task_struct *task,
diff -urpN linux-2.6/arch/s390/kernel/asm-offsets.c linux-2.6-patched/arch/s390/kernel/asm-offsets.c
--- linux-2.6/arch/s390/kernel/asm-offsets.c 2008-11-07 16:36:07.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/asm-offsets.c 2008-11-07 16:36:20.000000000 +0100
@@ -33,7 +33,7 @@ int main(void)
DEFINE(__PT_GPRS, offsetof(struct pt_regs, gprs));
DEFINE(__PT_ORIG_GPR2, offsetof(struct pt_regs, orig_gpr2));
DEFINE(__PT_ILC, offsetof(struct pt_regs, ilc));
- DEFINE(__PT_TRAP, offsetof(struct pt_regs, trap));
+ DEFINE(__PT_SVCNR, offsetof(struct pt_regs, svcnr));
DEFINE(__PT_SIZE, sizeof(struct pt_regs));
BLANK();
DEFINE(__SF_BACKCHAIN, offsetof(struct stack_frame, back_chain));
diff -urpN linux-2.6/arch/s390/kernel/compat_signal.c linux-2.6-patched/arch/s390/kernel/compat_signal.c
--- linux-2.6/arch/s390/kernel/compat_signal.c 2008-10-10 00:13:53.000000000 +0200
+++ linux-2.6-patched/arch/s390/kernel/compat_signal.c 2008-11-07 16:36:20.000000000 +0100
@@ -340,7 +340,7 @@ static int restore_sigregs32(struct pt_r
return err;
restore_fp_regs(¤t->thread.fp_regs);
- regs->trap = -1; /* disable syscall checks */
+ regs->svcnr = 0; /* disable syscall checks */
return 0;
}
diff -urpN linux-2.6/arch/s390/kernel/entry64.S linux-2.6-patched/arch/s390/kernel/entry64.S
--- linux-2.6/arch/s390/kernel/entry64.S 2008-11-07 16:36:04.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/entry64.S 2008-11-07 16:36:20.000000000 +0100
@@ -46,7 +46,7 @@ SP_R14 = STACK_FRAME_OVERHEAD + __P
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_
.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
diff -urpN linux-2.6/arch/s390/kernel/entry.S linux-2.6-patched/arch/s390/kernel/entry.S
--- linux-2.6/arch/s390/kernel/entry.S 2008-11-07 16:36:04.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/entry.S 2008-11-07 16:36:20.000000000 +0100
@@ -46,7 +46,7 @@ SP_R14 = STACK_FRAME_OVERHEAD + __P
SP_R15 = STACK_FRAME_OVERHEAD + __PT_GPRS + 60
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
_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
@@ -183,11 +183,10 @@ STACK_SIZE = 1 << STACK_SHIFT
.macro CREATE_STACK_FRAME psworg,savearea
s %r15,BASED(.Lc_spsize) # make room for registers & psw
mvc SP_PSW(8,%r15),0(%r12) # move user PSW to stack
- la %r12,\psworg
st %r2,SP_ORIG_R2(%r15) # store original content of gpr 2
- icm %r12,12,__LC_SVC_ILC
+ icm %r12,3,__LC_SVC_ILC
stm %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(16,%r15),\savearea # move %r12-%r15 to stack
la %r12,0
st %r12,__SF_BACKCHAIN(%r15) # clear back chain
@@ -264,16 +263,17 @@ sysc_update:
#endif
sysc_do_svc:
l %r9,__LC_THREAD_INFO # load pointer to thread_info struct
- sla %r7,2 # *4 and test for svc 0
+ ltr %r7,%r7 # test for svc 0
bnz BASED(sysc_nr_ok) # svc number > 0
# svc 0: system call number in %r1
cl %r1,BASED(.Lnr_syscalls)
bnl BASED(sysc_nr_ok)
lr %r7,%r1 # copy svc number to %r7
- sla %r7,2 # *4
sysc_nr_ok:
mvc SP_ARGS(4,%r15),SP_R7(%r15)
sysc_do_restart:
+ sth %r7,SP_SVCNR(%r15)
+ sll %r7,2 # svc number *4
l %r8,BASED(.Lsysc_table)
tm __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
l %r8,0(%r7,%r8) # get system call addr.
@@ -376,7 +376,6 @@ sysc_notify_resume:
sysc_restart:
ni __TI_flags+3(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
l %r7,SP_R2(%r15) # load new svc number
- sla %r7,2
mvc SP_R2(4,%r15),SP_ORIG_R2(%r15) # restore first argument
lm %r2,%r6,SP_R2(%r15) # load svc arguments
b BASED(sysc_do_restart) # restart svc
@@ -386,7 +385,8 @@ sysc_restart:
#
sysc_singlestep:
ni __TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
- mvi SP_TRAP+1(%r15),0x28 # set trap indication to pgm check
+ mvi SP_SVCNR(%r15),0xff # set trap indication to pgm check
+ mvi SP_SVCNR+1(%r15),0xff
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
@@ -407,7 +407,7 @@ sysc_tracesys:
bnl BASED(sysc_tracenogo)
l %r8,BASED(.Lsysc_table)
lr %r7,%r2
- sll %r7,2 # *4
+ sll %r7,2 # svc number *4
l %r8,0(%r7,%r8)
sysc_tracego:
lm %r3,%r6,SP_R3(%r15)
@@ -586,7 +586,8 @@ pgm_svcper:
# per was called from kernel, must be kprobes
#
kernel_per:
- mvi SP_TRAP+1(%r15),0x28 # set trap indication to pgm check
+ mvi SP_SVCNR(%r15),0xff # set trap indication to pgm check
+ mvi SP_SVCNR+1(%r15),0xff
la %r2,SP_PTREGS(%r15) # address of register-save area
l %r1,BASED(.Lhandle_per) # load adr. of per handler
la %r14,BASED(sysc_restore)# load adr. of system return
diff -urpN linux-2.6/arch/s390/kernel/ptrace.c linux-2.6-patched/arch/s390/kernel/ptrace.c
--- linux-2.6/arch/s390/kernel/ptrace.c 2008-11-07 16:36:18.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/ptrace.c 2008-11-07 16:36:20.000000000 +0100
@@ -655,7 +655,7 @@ asmlinkage long do_syscall_trace_enter(s
* debugger stored an invalid system call number. Skip
* the system call and the system call restart handling.
*/
- regs->trap = -1;
+ regs->svcnr = 0;
ret = -1;
}
diff -urpN linux-2.6/arch/s390/kernel/signal.c linux-2.6-patched/arch/s390/kernel/signal.c
--- linux-2.6/arch/s390/kernel/signal.c 2008-11-07 16:35:54.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/signal.c 2008-11-07 16:36:20.000000000 +0100
@@ -160,7 +160,7 @@ static int restore_sigregs(struct pt_reg
current->thread.fp_regs.fpc &= FPC_VALID_MASK;
restore_fp_regs(¤t->thread.fp_regs);
- regs->trap = -1; /* disable syscall checks */
+ regs->svcnr = 0; /* disable syscall checks */
return 0;
}
@@ -445,7 +445,7 @@ void do_signal(struct pt_regs *regs)
oldset = ¤t->blocked;
/* Are we from a system call? */
- if (regs->trap == __LC_SVC_OLD_PSW) {
+ if (regs->svcnr) {
continue_addr = regs->psw.addr;
restart_addr = continue_addr - regs->ilc;
retval = regs->gprs[2];
@@ -462,7 +462,7 @@ void do_signal(struct pt_regs *regs)
case -ERESTART_RESTARTBLOCK:
regs->gprs[2] = -EINTR;
}
- regs->trap = -1; /* Don't deal with this again. */
+ regs->svcnr = 0; /* Don't deal with this again. */
}
/* Get signal to deliver. When running under ptrace, at this point
--
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