[PATCH v2 35/70] x86/ucode: CFI hardening

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Control Flow Integrity schemes use toolchain and optionally hardware support
to help protect against call/jump/return oriented programming attacks.

Use cf_check to annotate function pointer targets for the toolchain.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/cpu/microcode/amd.c   |  9 +++++----
 xen/arch/x86/cpu/microcode/core.c  |  4 ++--
 xen/arch/x86/cpu/microcode/intel.c | 10 +++++-----
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/cpu/microcode/amd.c b/xen/arch/x86/cpu/microcode/amd.c
index fe92e594f129..0afa2192bf1d 100644
--- a/xen/arch/x86/cpu/microcode/amd.c
+++ b/xen/arch/x86/cpu/microcode/amd.c
@@ -91,7 +91,7 @@ static struct {
     uint16_t id;
 } equiv __read_mostly;
 
-static void collect_cpu_info(void)
+static void cf_check collect_cpu_info(void)
 {
     struct cpu_signature *csig = &this_cpu(cpu_sig);
 
@@ -204,7 +204,7 @@ static enum microcode_match_result compare_header(
     return compare_revisions(old->patch_id, new->patch_id);
 }
 
-static enum microcode_match_result compare_patch(
+static enum microcode_match_result cf_check compare_patch(
     const struct microcode_patch *new, const struct microcode_patch *old)
 {
     /* Both patches to compare are supposed to be applicable to local CPU. */
@@ -214,7 +214,7 @@ static enum microcode_match_result compare_patch(
     return compare_header(new, old);
 }
 
-static int apply_microcode(const struct microcode_patch *patch)
+static int cf_check apply_microcode(const struct microcode_patch *patch)
 {
     int hw_err;
     unsigned int cpu = smp_processor_id();
@@ -299,7 +299,8 @@ static int scan_equiv_cpu_table(const struct 
container_equiv_table *et)
     return -ESRCH;
 }
 
-static struct microcode_patch *cpu_request_microcode(const void *buf, size_t 
size)
+static struct microcode_patch *cf_check cpu_request_microcode(
+    const void *buf, size_t size)
 {
     const struct microcode_patch *saved = NULL;
     struct microcode_patch *patch = NULL;
diff --git a/xen/arch/x86/cpu/microcode/core.c 
b/xen/arch/x86/cpu/microcode/core.c
index 841364208053..c07f68ba350e 100644
--- a/xen/arch/x86/cpu/microcode/core.c
+++ b/xen/arch/x86/cpu/microcode/core.c
@@ -291,12 +291,12 @@ static int wait_for_condition(bool (*func)(unsigned int 
data),
     return 0;
 }
 
-static bool wait_cpu_callin(unsigned int nr)
+static bool cf_check wait_cpu_callin(unsigned int nr)
 {
     return cpumask_weight(&cpu_callin_map) >= nr;
 }
 
-static bool wait_cpu_callout(unsigned int nr)
+static bool cf_check wait_cpu_callout(unsigned int nr)
 {
     return atomic_read(&cpu_out) >= nr;
 }
diff --git a/xen/arch/x86/cpu/microcode/intel.c 
b/xen/arch/x86/cpu/microcode/intel.c
index f6d01490e0ab..d3864b5ab03e 100644
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -116,7 +116,7 @@ static bool signature_matches(const struct cpu_signature 
*cpu_sig,
     return cpu_sig->pf & ucode_pf;
 }
 
-static void collect_cpu_info(void)
+static void cf_check collect_cpu_info(void)
 {
     struct cpu_signature *csig = &this_cpu(cpu_sig);
     uint64_t msr_content;
@@ -271,7 +271,7 @@ static enum microcode_match_result microcode_update_match(
     return compare_revisions(cpu_sig->rev, mc->rev);
 }
 
-static enum microcode_match_result compare_patch(
+static enum microcode_match_result cf_check compare_patch(
     const struct microcode_patch *new, const struct microcode_patch *old)
 {
     /*
@@ -284,7 +284,7 @@ static enum microcode_match_result compare_patch(
     return compare_revisions(old->rev, new->rev);
 }
 
-static int apply_microcode(const struct microcode_patch *patch)
+static int cf_check apply_microcode(const struct microcode_patch *patch)
 {
     uint64_t msr_content;
     unsigned int cpu = smp_processor_id();
@@ -323,8 +323,8 @@ static int apply_microcode(const struct microcode_patch 
*patch)
     return 0;
 }
 
-static struct microcode_patch *cpu_request_microcode(const void *buf,
-                                                     size_t size)
+static struct microcode_patch *cf_check cpu_request_microcode(
+    const void *buf, size_t size)
 {
     int error = 0;
     const struct microcode_patch *saved = NULL;
-- 
2.11.0