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| author |   Josh Poimboeuf <jpoimboe@kernel.org> | 2022-08-26 16:55:44 -0700 |
|---|---|---|
| committer |   Vasily Gorbik <gor@linux.ibm.com> | 2022-08-30 21:57:07 +0200 |
| commit | c9305b6c1f52060377c72aebe3a701389e9f3172 (patch) | |
| tree | c2bde53b10c7bd049895f69e492e318e05df421a /arch | |
| parent | s390/mm: remove useless hugepage address alignment (diff) | |
| download | linux-dev-c9305b6c1f52060377c72aebe3a701389e9f3172.tar.xz linux-dev-c9305b6c1f52060377c72aebe3a701389e9f3172.zip | |
s390: fix nospec table alignments
Add proper alignment for .nospec_call_table and .nospec_return_table in
vmlinux.
[hca@linux.ibm.com]: The problem with the missing alignment of the nospec
tables exist since a long time, however only since commit e6ed91fd0768
("s390/alternatives: remove padding generation code") and with
CONFIG_RELOCATABLE=n the kernel may also crash at boot time.
The above named commit reduced the size of struct alt_instr by one byte,
so its new size is 11 bytes. Therefore depending on the number of cpu
alternatives the size of the __alt_instructions array maybe odd, which
again also causes that the addresses of the nospec tables will be odd.
If the address of __nospec_call_start is odd and the kernel is compiled
With CONFIG_RELOCATABLE=n the compiler may generate code that loads the
address of __nospec_call_start with a 'larl' instruction.
This will generate incorrect code since the 'larl' instruction only works
with even addresses. In result the members of the nospec tables will be
accessed with an off-by-one offset, which subsequently may lead to
addressing exceptions within __nospec_revert().
Fixes: f19fbd5ed642 ("s390: introduce execute-trampolines for branches")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/8719bf1ce4a72ebdeb575200290094e9ce047bcc.1661557333.git.jpoimboe@kernel.org
Cc: <stable@vger.kernel.org> # 4.16
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/kernel/vmlinux.lds.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S index 2e526f11b91e..5ea3830af0cc 100644 --- a/arch/s390/kernel/vmlinux.lds.S +++ b/arch/s390/kernel/vmlinux.lds.S @@ -131,6 +131,7 @@ SECTIONS /* * Table with the patch locations to undo expolines */ + . = ALIGN(4); .nospec_call_table : { __nospec_call_start = . ; *(.s390_indirect*) |