SoftwareUpdate.cpp: Fix hw.optional reporting

acidanthera · Apr 13, 2023 · 495f4d5 · 495f4d5
1 parent d725f95
commit 495f4d5
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Showing 3 changed files with 19 additions and 5 deletions.
diff --git a/Changelog.md b/Changelog.md
@@ -1,5 +1,8 @@
 RestrictEvents Changelog
 ========================
+#### v1.1.1
+- Fixed `f16c` patch misreporting other `hw.optional` features
+
 #### v1.1.0
 - Added `hw.optional.f16c` disabling for macOS 13.3+
   - Resolves CoreGraphics.framework invoking AVX2.0 code paths on Ivy Bridge CPUs

diff --git a/RestrictEvents/SoftwareUpdate.cpp b/RestrictEvents/SoftwareUpdate.cpp
@@ -159,9 +159,16 @@ static int my_sysctl_vmm_present(__unused struct sysctl_oid *oidp, __unused void
 	return FunctionCast(my_sysctl_vmm_present, org_sysctl_vmm_present)(oidp, arg1, arg2, req);
 }
 
-static int my_sysctl_f16c(__unused struct sysctl_oid *oidp, __unused void *arg1, int arg2, struct sysctl_req *req) {
-	int f16c_off = 0;
-	return SYSCTL_OUT(req, &f16c_off, sizeof(f16c_off));
+
+static mach_vm_address_t org_sysctl_f16c;
+static int my_sysctl_f16c(__unused struct sysctl_oid *oidp, void *arg1, int arg2, struct sysctl_req *req) {
+	// Strip F16C bit from arg1
+	// Ref: https://github.com/apple-oss-distributions/xnu/blob/xnu-8020.101.4/bsd/kern/kern_mib.c#L935-L946
+	int mask = (uint64_t) (uintptr_t) arg1 & ~kHasF16C;
+
+	// Convert back
+	arg1 = (void *) (uintptr_t) mask;
+	return FunctionCast(my_sysctl_f16c, org_sysctl_f16c)(oidp, arg1, arg2, req);
 }
 
 
@@ -200,8 +207,10 @@ void reroutef16c(KernelPatcher &patcher) {
 		SYSLOG("supd", "failed to resolve hw.optional.f16c sysctl");
 		return;
 	}
-
-	if (!patcher.routeFunction(reinterpret_cast<mach_vm_address_t>(f16c->oid_handler), reinterpret_cast<mach_vm_address_t>(my_sysctl_f16c), true)) {
+
+	org_sysctl_f16c = patcher.routeFunction(reinterpret_cast<mach_vm_address_t>(f16c->oid_handler), reinterpret_cast<mach_vm_address_t>(my_sysctl_f16c), true);
+
+	if (!org_sysctl_f16c) {
 		SYSLOG("supd", "failed to route hw.optional.f16c sysctl");
 		patcher.clearError();
 		return;

diff --git a/RestrictEvents/SoftwareUpdate.hpp b/RestrictEvents/SoftwareUpdate.hpp
@@ -27,6 +27,8 @@
 
 #define HW_PRODUCT      27
 
+#define kHasF16C        0x04000000
+
 typedef int (* sysctl_handler_t)(struct sysctl_oid *oidp __unused, void *arg1 __unused, int arg2 __unused, struct sysctl_req *req);
 
 struct sysctl_oid {