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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2009-07-24 10:39:52 (GMT) |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2009-07-24 10:41:02 (GMT) |
| commit | 1277580fe5dfb5aef84854bdb7983657df00b920 (patch) | |
| tree | 1cfde8482a43f0f0ba56ac488a4cacf52d89fd61 | |
| parent | 3a6ba4600d6fb913ddb0dd08843ad75405795883 (diff) | |
| download | linux-1277580fe5dfb5aef84854bdb7983657df00b920.tar.xz | |
[S390] vdso: clock_gettime of CLOCK_THREAD_CPUTIME_ID with noexec=on
The combination of noexec=on and a clock_gettime call with clock id
CLOCK_THREAD_CPUTIME_ID is broken. The vdso code switches to the
access register mode to get access to the per-cpu data structure to
execute the magic ectg instruction. After the ectg instruction the
code always switches back to the primary mode but for noexec=on the
correct mode is the secondary mode. The effect of the bug is that the
user space program looses the access to all mappings without PROT_EXEC,
e.g. the stack. The problem is fixed by restoring the mode that has
been active before the switch to the access register mode.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
| -rw-r--r-- | arch/s390/kernel/vdso64/clock_gettime.S | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/s390/kernel/vdso64/clock_gettime.S b/arch/s390/kernel/vdso64/clock_gettime.S index 79dbfee..49106c6 100644 --- a/arch/s390/kernel/vdso64/clock_gettime.S +++ b/arch/s390/kernel/vdso64/clock_gettime.S @@ -88,10 +88,17 @@ __kernel_clock_gettime: llilh %r4,0x0100 sar %a4,%r4 lghi %r4,0 + epsw %r5,0 sacf 512 /* Magic ectg instruction */ .insn ssf,0xc80100000000,__VDSO_ECTG_BASE(4),__VDSO_ECTG_USER(4),4 - sacf 0 - sar %a4,%r2 + tml %r5,0x4000 + jo 11f + tml %r5,0x8000 + jno 10f + sacf 256 + j 11f +10: sacf 0 +11: sar %a4,%r2 algr %r1,%r0 /* r1 = cputime as TOD value */ mghi %r1,1000 /* convert to nanoseconds */ srlg %r1,%r1,12 /* r1 = cputime in nanosec */ |