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s390/ptrace: pass invalid syscall numbers to tracing 

tracing expects to see invalid syscalls, so pass it through.
The syscall path in entry.S checks the syscall number before
looking up the handler, so it is still safe.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Sven Schnelle 2020-03-06 13:19:34 +01:00 committed by Vasily Gorbik
parent cd29fa7980
commit 00332c16b1
2 changed files with 3 additions and 5 deletions
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2
arch/s390/kernel/entry.S
View File

@ -401,9 +401,9 @@ ENTRY(system_call)
jnz .Lsysc_nr_ok
# svc 0: system call number in %r1
llgfr %r1,%r1 # clear high word in r1
sth %r1,__PT_INT_CODE+2(%r11)
cghi %r1,NR_syscalls
jnl .Lsysc_nr_ok
sth %r1,__PT_INT_CODE+2(%r11)
slag %r8,%r1,3
.Lsysc_nr_ok:
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

6
arch/s390/kernel/ptrace.c
View File

@ -847,11 +847,9 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
* call number to gprs[2].
*/
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
(tracehook_report_syscall_entry(regs) ||
regs->gprs[2] >= NR_syscalls)) {
tracehook_report_syscall_entry(regs)) {
/*
* Tracing decided this syscall should not happen or the
* debugger stored an invalid system call number. Skip
* Tracing decided this syscall should not happen. Skip
* the system call and the system call restart handling.
*/
goto skip;