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| author | Vasily Gorbik <gor@linux.ibm.com> | 2019-01-02 15:43:22 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-11-20 20:47:53 +0300 |
| commit | 2ed924f2782fc34cfd763b6e61ba433c16d8db4c (patch) | |
| tree | 3deb9761f2e756638178caa92eef050010d9035f /arch/s390 | |
| parent | 1b904b2eb9c1d9216e1be9f4615952bcd6b99856 (diff) | |
| download | linux-2ed924f2782fc34cfd763b6e61ba433c16d8db4c.tar.xz | |
s390/vdso: correct vdso mapping for compat tasks
[ Upstream commit 190f056fba230abee80712eb810939ef9a8c462f ]
While "s390/vdso: avoid 64-bit vdso mapping for compat tasks" fixed
64-bit vdso mapping for compat tasks under gdb it introduced another
problem. "compat_mm" flag is not inherited during fork and when
31-bit process forks a child (but does not perform exec) it ends up
with 64-bit vdso. To address that, init_new_context (which is called
during fork and exec) now initialize compat_mm based on thread TIF_31BIT
flag. Later compat_mm is adjusted in arch_setup_additional_pages, which
is called during exec.
Fixes: d1befa65823e ("s390/vdso: avoid 64-bit vdso mapping for compat tasks")
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/mmu_context.h | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/vdso.c | 5 |
2 files changed, 3 insertions, 4 deletions
diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h index e4462202200d..8d04e6f3f796 100644 --- a/arch/s390/include/asm/mmu_context.h +++ b/arch/s390/include/asm/mmu_context.h @@ -25,7 +25,7 @@ static inline int init_new_context(struct task_struct *tsk, atomic_set(&mm->context.flush_count, 0); mm->context.gmap_asce = 0; mm->context.flush_mm = 0; - mm->context.compat_mm = 0; + mm->context.compat_mm = test_thread_flag(TIF_31BIT); #ifdef CONFIG_PGSTE mm->context.alloc_pgste = page_table_allocate_pgste || test_thread_flag(TIF_PGSTE) || diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index ec31b48a42a5..7ab7d256d1eb 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -224,10 +224,9 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) { + mm->context.compat_mm = is_compat_task(); + if (mm->context.compat_mm) vdso_pages = vdso32_pages; - mm->context.compat_mm = 1; - } #endif /* * vDSO has a problem and was disabled, just don't "enable" it for |