[PATCH v2 43/70] x86/mce: 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/mcheck/mce.c       |  8 ++++----
 xen/arch/x86/cpu/mcheck/mce.h       |  2 +-
 xen/arch/x86/cpu/mcheck/mce_amd.c   |  9 ++++----
 xen/arch/x86/cpu/mcheck/mce_amd.h   |  4 ++--
 xen/arch/x86/cpu/mcheck/mce_intel.c | 41 +++++++++++++++++--------------------
 5 files changed, 31 insertions(+), 33 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 3467e0f1a315..275c54be7c0f 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -75,7 +75,7 @@ static int __init cf_check mce_set_verbosity(const char *str)
 custom_param("mce_verbosity", mce_set_verbosity);
 
 /* Handle unconfigured int18 (should never happen) */
-static void unexpected_machine_check(const struct cpu_user_regs *regs)
+static void cf_check unexpected_machine_check(const struct cpu_user_regs *regs)
 {
     console_force_unlock();
     printk("Unexpected Machine Check Exception\n");
@@ -469,7 +469,7 @@ static int mce_urgent_action(const struct cpu_user_regs 
*regs,
 }
 
 /* Shared #MC handler. */
-void mcheck_cmn_handler(const struct cpu_user_regs *regs)
+void cf_check mcheck_cmn_handler(const struct cpu_user_regs *regs)
 {
     static DEFINE_MCE_BARRIER(mce_trap_bar);
     static atomic_t severity_cpu = ATOMIC_INIT(-1);
@@ -1684,7 +1684,7 @@ long cf_check do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) 
u_xen_mc)
 }
 
 int mcinfo_dumpped;
-static int x86_mcinfo_dump_panic(mctelem_cookie_t mctc)
+static int cf_check x86_mcinfo_dump_panic(mctelem_cookie_t mctc)
 {
     struct mc_info *mcip = mctelem_dataptr(mctc);
 
@@ -1801,7 +1801,7 @@ static enum mce_result mce_action(const struct 
cpu_user_regs *regs,
  * should be committed for dom0 consumption, 0 if it should be
  * dismissed.
  */
-static int mce_delayed_action(mctelem_cookie_t mctc)
+static int cf_check mce_delayed_action(mctelem_cookie_t mctc)
 {
     enum mce_result result;
     int ret = 0;
diff --git a/xen/arch/x86/cpu/mcheck/mce.h b/xen/arch/x86/cpu/mcheck/mce.h
index 195362691904..535d0abf8f9b 100644
--- a/xen/arch/x86/cpu/mcheck/mce.h
+++ b/xen/arch/x86/cpu/mcheck/mce.h
@@ -70,7 +70,7 @@ extern void x86_mce_vector_register(x86_mce_vector_t);
  * Common generic MCE handler that implementations may nominate
  * via x86_mce_vector_register.
  */
-extern void mcheck_cmn_handler(const struct cpu_user_regs *regs);
+void cf_check mcheck_cmn_handler(const struct cpu_user_regs *regs);
 
 /* Register a handler for judging whether mce is recoverable. */
 typedef bool (*mce_recoverable_t)(uint64_t status);
diff --git a/xen/arch/x86/cpu/mcheck/mce_amd.c 
b/xen/arch/x86/cpu/mcheck/mce_amd.c
index 279a8e6f122d..d7ae8919df77 100644
--- a/xen/arch/x86/cpu/mcheck/mce_amd.c
+++ b/xen/arch/x86/cpu/mcheck/mce_amd.c
@@ -113,7 +113,7 @@ mc_ec2type(uint16_t errorcode)
     return 0;
 }
 
-bool mc_amd_recoverable_scan(uint64_t status)
+bool cf_check mc_amd_recoverable_scan(uint64_t status)
 {
     bool ret = false;
     enum mc_ec_type ectype;
@@ -143,7 +143,7 @@ bool mc_amd_recoverable_scan(uint64_t status)
     return ret;
 }
 
-bool mc_amd_addrcheck(uint64_t status, uint64_t misc, int addrtype)
+bool cf_check mc_amd_addrcheck(uint64_t status, uint64_t misc, int addrtype)
 {
     enum mc_ec_type ectype;
     uint16_t errorcode;
@@ -216,7 +216,7 @@ static void mcequirk_amd_apply(enum mcequirk_amd_flags 
flags)
     }
 }
 
-static struct mcinfo_extended *
+static struct mcinfo_extended *cf_check
 amd_f10_handler(struct mc_info *mi, uint16_t bank, uint64_t status)
 {
     struct mcinfo_extended *mc_ext;
@@ -252,7 +252,8 @@ amd_f10_handler(struct mc_info *mi, uint16_t bank, uint64_t 
status)
     return mc_ext;
 }
 
-static bool amd_need_clearbank_scan(enum mca_source who, uint64_t status)
+static bool cf_check amd_need_clearbank_scan(
+    enum mca_source who, uint64_t status)
 {
     if ( who != MCA_MCE_SCAN )
         return true;
diff --git a/xen/arch/x86/cpu/mcheck/mce_amd.h 
b/xen/arch/x86/cpu/mcheck/mce_amd.h
index 67c45454707d..c12c25d74567 100644
--- a/xen/arch/x86/cpu/mcheck/mce_amd.h
+++ b/xen/arch/x86/cpu/mcheck/mce_amd.h
@@ -1,7 +1,7 @@
 #ifndef _MCHECK_AMD_H
 #define _MCHECK_AMD_H
 
-bool mc_amd_recoverable_scan(uint64_t status);
-bool mc_amd_addrcheck(uint64_t status, uint64_t misc, int addrtype);
+bool cf_check mc_amd_recoverable_scan(uint64_t status);
+bool cf_check mc_amd_addrcheck(uint64_t status, uint64_t misc, int addrtype);
 
 #endif
diff --git a/xen/arch/x86/cpu/mcheck/mce_intel.c 
b/xen/arch/x86/cpu/mcheck/mce_intel.c
index 7aaa56fd02eb..50198e0c295c 100644
--- a/xen/arch/x86/cpu/mcheck/mce_intel.c
+++ b/xen/arch/x86/cpu/mcheck/mce_intel.c
@@ -271,12 +271,13 @@ static void intel_memerr_dhandler(
     mc_memerr_dhandler(binfo, result, regs);
 }
 
-static bool intel_srar_check(uint64_t status)
+static bool cf_check intel_srar_check(uint64_t status)
 {
     return (intel_check_mce_type(status) == intel_mce_ucr_srar);
 }
 
-static bool intel_checkaddr(uint64_t status, uint64_t misc, int addrtype)
+static bool cf_check intel_checkaddr(
+    uint64_t status, uint64_t misc, int addrtype)
 {
     if ( !(status & MCi_STATUS_ADDRV) ||
          !(status & MCi_STATUS_MISCV) ||
@@ -287,10 +288,9 @@ static bool intel_checkaddr(uint64_t status, uint64_t 
misc, int addrtype)
     return (addrtype == MC_ADDR_PHYSICAL);
 }
 
-static void intel_srar_dhandler(
-             struct mca_binfo *binfo,
-             enum mce_result *result,
-             const struct cpu_user_regs *regs)
+static void cf_check intel_srar_dhandler(
+    struct mca_binfo *binfo, enum mce_result *result,
+    const struct cpu_user_regs *regs)
 {
     uint64_t status = binfo->mib->mc_status;
 
@@ -306,15 +306,14 @@ static void intel_srar_dhandler(
     }
 }
 
-static bool intel_srao_check(uint64_t status)
+static bool cf_check intel_srao_check(uint64_t status)
 {
     return (intel_check_mce_type(status) == intel_mce_ucr_srao);
 }
 
-static void intel_srao_dhandler(
-             struct mca_binfo *binfo,
-             enum mce_result *result,
-             const struct cpu_user_regs *regs)
+static void cf_check intel_srao_dhandler(
+    struct mca_binfo *binfo, enum mce_result *result,
+    const struct cpu_user_regs *regs)
 {
     uint64_t status = binfo->mib->mc_status;
 
@@ -333,15 +332,14 @@ static void intel_srao_dhandler(
     }
 }
 
-static bool intel_default_check(uint64_t status)
+static bool cf_check intel_default_check(uint64_t status)
 {
     return true;
 }
 
-static void intel_default_mce_dhandler(
-             struct mca_binfo *binfo,
-             enum mce_result *result,
-             const struct cpu_user_regs * regs)
+static void cf_check intel_default_mce_dhandler(
+    struct mca_binfo *binfo, enum mce_result *result,
+    const struct cpu_user_regs * regs)
 {
     uint64_t status = binfo->mib->mc_status;
     enum intel_mce_type type;
@@ -360,10 +358,9 @@ static const struct mca_error_handler 
intel_mce_dhandlers[] = {
     {intel_default_check, intel_default_mce_dhandler}
 };
 
-static void intel_default_mce_uhandler(
-             struct mca_binfo *binfo,
-             enum mce_result *result,
-             const struct cpu_user_regs *regs)
+static void cf_check intel_default_mce_uhandler(
+    struct mca_binfo *binfo, enum mce_result *result,
+    const struct cpu_user_regs *regs)
 {
     uint64_t status = binfo->mib->mc_status;
     enum intel_mce_type type;
@@ -396,7 +393,7 @@ static const struct mca_error_handler intel_mce_uhandlers[] 
= {
  * 3) ser_support = 1, SRAO, UC = 1, S = 1, AR = 0, [EN = 1]
  */
 
-static bool intel_need_clearbank_scan(enum mca_source who, u64 status)
+static bool cf_check intel_need_clearbank_scan(enum mca_source who, u64 status)
 {
     if ( who == MCA_CMCI_HANDLER )
     {
@@ -453,7 +450,7 @@ static bool intel_need_clearbank_scan(enum mca_source who, 
u64 status)
  * 4) SRAO ser_support = 1, PCC = 0, S = 1, AR = 0, EN = 1 [UC = 1]
  * 5) UCNA ser_support = 1, OVER = 0, EN = 1, PCC = 0, S = 0, AR = 0, [UC = 1]
  */
-static bool intel_recoverable_scan(uint64_t status)
+static bool cf_check intel_recoverable_scan(uint64_t status)
 {
 
     if ( !(status & MCi_STATUS_UC ) )
-- 
2.11.0