Alternatives patching code picks the most suitable NOPs for the
running system, so simply use it to replace the pre-populated ones.
Use an arbitrary, always available feature to key off from.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -185,6 +185,7 @@ ENTRY(compat_restore_all_guest)
mov %rax, %cr4
.Lcr4_alt_end:
.section .altinstructions, "a"
+ altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_LM, 12, 0
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMEP, 12, \
(.Lcr4_alt_end - .Lcr4_alt)
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMAP, 12, \
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -204,6 +204,7 @@ void ret_from_intr(void);
662: __ASM_##op; \
.popsection; \
.pushsection .altinstructions, "a"; \
+ altinstruction_entry 661b, 661b, X86_FEATURE_LM, 3, 0; \
altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3; \
.popsection
@@ -215,6 +216,7 @@ void ret_from_intr(void);
.pushsection .altinstr_replacement, "ax"; \
668: call cr4_smep_smap_restore; \
.section .altinstructions, "a"; \
+ altinstruction_entry 667b, 667b, X86_FEATURE_LM, 5, 0; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMEP, 5, 5; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMAP, 5, 5; \
.popsection
x86: use optimal NOPs to fill the SMAP/SMEP placeholders
Alternatives patching code picks the most suitable NOPs for the
running system, so simply use it to replace the pre-populated ones.
Use an arbitrary, always available feature to key off from.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -185,6 +185,7 @@ ENTRY(compat_restore_all_guest)
mov %rax, %cr4
.Lcr4_alt_end:
.section .altinstructions, "a"
+ altinstruction_entry .Lcr4_orig, .Lcr4_orig, X86_FEATURE_LM, 12, 0
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMEP, 12, \
(.Lcr4_alt_end - .Lcr4_alt)
altinstruction_entry .Lcr4_orig, .Lcr4_alt, X86_FEATURE_SMAP, 12, \
--- a/xen/include/asm-x86/asm_defns.h
+++ b/xen/include/asm-x86/asm_defns.h
@@ -204,6 +204,7 @@ void ret_from_intr(void);
662: __ASM_##op; \
.popsection; \
.pushsection .altinstructions, "a"; \
+ altinstruction_entry 661b, 661b, X86_FEATURE_LM, 3, 0; \
altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3; \
.popsection
@@ -215,6 +216,7 @@ void ret_from_intr(void);
.pushsection .altinstr_replacement, "ax"; \
668: call cr4_smep_smap_restore; \
.section .altinstructions, "a"; \
+ altinstruction_entry 667b, 667b, X86_FEATURE_LM, 5, 0; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMEP, 5, 5; \
altinstruction_entry 667b, 668b, X86_FEATURE_SMAP, 5, 5; \
.popsection
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