Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752681AbYKGPlP (ORCPT ); Fri, 7 Nov 2008 10:41:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753870AbYKGPkv (ORCPT ); Fri, 7 Nov 2008 10:40:51 -0500 Received: from mtagate7.de.ibm.com ([195.212.29.156]:55906 "EHLO mtagate7.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753333AbYKGPkt (ORCPT ); Fri, 7 Nov 2008 10:40:49 -0500 Subject: Re: [patch 15/21] ptrace changes From: Martin Schwidefsky Reply-To: schwidefsky@de.ibm.com To: David Smith Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Heiko Carstens In-Reply-To: <49133665.8090701@redhat.com> References: <20081001083317.782967473@de.ibm.com> <20081001084129.042880937@de.ibm.com> <490F317C.9040603@redhat.com> <1225885284.17430.7.camel@localhost> <49133665.8090701@redhat.com> Content-Type: text/plain Organization: IBM Corporation Date: Fri, 07 Nov 2008 16:32:33 +0100 Message-Id: <1226071953.5830.33.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 12508 Lines: 316 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 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 Signed-off-by: Martin Schwidefsky --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/