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s390/ptrace: pass invalid syscall numbers to tracing 

[ Upstream commit 00332c16b1 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Sven Schnelle 2020-03-06 13:19:34 +01:00 committed by Sasha Levin
parent 453cfe1877
commit 64f7b10a91
2 changed files with 3 additions and 5 deletions
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2
arch/s390/kernel/entry.S
View File

@ -368,9 +368,9 @@ 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

@ -844,11 +844,9 @@ 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.
*/
clear_pt_regs_flag(regs, PIF_SYSCALL);