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s390: add automatic detection of the spectre defense

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Automatically decide between nobp vs. expolines if the spectre_v2=auto
kernel parameter is specified or CONFIG_EXPOLINE_AUTO=y is set.

The decision made at boot time due to CONFIG_EXPOLINE_AUTO=y being set
can be overruled with the nobp, nospec and spectre_v2 kernel parameters.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2018-03-23 13:04:49 +01:00
parent b2e2f43a01
commit 6e179d6412
6 changed files with 52 additions and 38 deletions
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11
arch/s390/kernel/module.c
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@@ -159,7 +159,7 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
me->core_layout.size += me->arch.got_size;
me->arch.plt_offset = me->core_layout.size;
if (me->arch.plt_size) {
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_call_disable)
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable)
me->arch.plt_size += PLT_ENTRY_SIZE;
me->core_layout.size += me->arch.plt_size;
}
@@ -318,8 +318,7 @@ static int apply_rela(Elf_Rela *rela, Elf_Addr base, Elf_Sym *symtab,
info->plt_offset;
ip[0] = 0x0d10e310; /* basr 1,0 */
ip[1] = 0x100a0004; /* lg 1,10(1) */
if (IS_ENABLED(CONFIG_EXPOLINE) &&
!nospec_call_disable) {
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
unsigned int *ij;
ij = me->core_layout.base +
me->arch.plt_offset +
@@ -440,7 +439,7 @@ int module_finalize(const Elf_Ehdr *hdr,
void *aseg;
if (IS_ENABLED(CONFIG_EXPOLINE) &&
!nospec_call_disable && me->arch.plt_size) {
!nospec_disable && me->arch.plt_size) {
unsigned int *ij;
ij = me->core_layout.base + me->arch.plt_offset +
@@ -467,11 +466,11 @@ int module_finalize(const Elf_Ehdr *hdr,
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(!strcmp(".nospec_call_table", secname)))
nospec_call_revert(aseg, aseg + s->sh_size);
nospec_revert(aseg, aseg + s->sh_size);
if (IS_ENABLED(CONFIG_EXPOLINE) &&
(!strcmp(".nospec_return_table", secname)))
nospec_return_revert(aseg, aseg + s->sh_size);
nospec_revert(aseg, aseg + s->sh_size);
}
jump_label_apply_nops(me);