Ensure at build time the feature(s) used for the alternative blocks are in
range of the featureset.
No functional change intended, as all current usages are correct.
Signed-off-by: Roger Pau Monné <roger....@citrix.com>
---
Changes since v1:
- New in this version.
---
xen/arch/x86/include/asm/alternative-asm.h | 3 +++
xen/arch/x86/include/asm/alternative.h | 4 ++++
2 files changed, 7 insertions(+)
diff --git a/xen/arch/x86/include/asm/alternative-asm.h
b/xen/arch/x86/include/asm/alternative-asm.h
index 4092f5ba70a6..83e8594f0eaf 100644
--- a/xen/arch/x86/include/asm/alternative-asm.h
+++ b/xen/arch/x86/include/asm/alternative-asm.h
@@ -12,6 +12,9 @@
* instruction. See apply_alternatives().
*/
.macro altinstruction_entry orig, repl, feature, orig_len, repl_len, pad_len
+ .if \feature >= NCAPINTS * 32
+ .error "alternative feature outside of featureset range"
+ .endif
.long \orig - .
.long \repl - .
.word \feature
diff --git a/xen/arch/x86/include/asm/alternative.h
b/xen/arch/x86/include/asm/alternative.h
index 69555d781ef9..b7f155994b2c 100644
--- a/xen/arch/x86/include/asm/alternative.h
+++ b/xen/arch/x86/include/asm/alternative.h
@@ -7,6 +7,7 @@
#include <xen/lib.h>
#include <xen/stringify.h>
#include <asm/asm-macros.h>
+#include <asm/cpufeatureset.h>
struct __packed alt_instr {
int32_t orig_offset; /* original instruction */
@@ -59,6 +60,9 @@ extern void alternative_branches(void);
alt_repl_len(n2)) "-" alt_orig_len)
#define ALTINSTR_ENTRY(feature, num) \
+ " .if " __stringify(feature) " >= " __stringify(NCAPINTS * 32) "\n"\
+ " .error \"alternative feature outside of featureset range\"\n" \
+ " .endif\n" \
" .long .LXEN%=_orig_s - .\n" /* label */ \
" .long " alt_repl_s(num)" - .\n" /* new instruction */ \
" .word " __stringify(feature) "\n" /* feature bit */ \
--
2.46.0
