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s390: correct module section names for expoline code revert

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[ Upstream commit 6cf09958f3 ]

The main linker script vmlinux.lds.S for the kernel image merges
the expoline code patch tables into two section ".nospec_call_table"
and ".nospec_return_table". This is *not* done for the modules,
there the sections retain their original names as generated by gcc:
".s390_indirect_call", ".s390_return_mem" and ".s390_return_reg".

The module_finalize code has to check for the compiler generated
section names, otherwise no code patching is done. This slows down
the module code in case of "spectre_v2=off".

Cc: stable@vger.kernel.org # 4.16
Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Martin Schwidefsky 2018-04-27 07:37:02 +02:00 committed by Greg Kroah-Hartman
parent c2d46e7be4
commit 01d5df5443
1 changed files with 2 additions and 2 deletions
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4
arch/s390/kernel/module.c
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@ -473,11 +473,11 @@ int module_finalize(const Elf_Ehdr *hdr,
apply_alternatives(aseg, aseg + s->sh_size);
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(!strcmp(".nospec_call_table", secname)))
(!strncmp(".s390_indirect", secname, 14)))
nospec_revert(aseg, aseg + s->sh_size);
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(!strcmp(".nospec_return_table", secname)))
(!strncmp(".s390_return", secname, 12)))
nospec_revert(aseg, aseg + s->sh_size);
}