kernel/amd64: Add 'feat' field in cpu_info

Keep track of per-cpu features by using a 'feat' field which contains
the results of various CPUIDs.

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 21 insertions, 0 deletions

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index 8258f8e..408ac95 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -178,6 +178,19 @@ enable_simd(void)
     }
 }
 
+static void
+cpu_check_feat(struct cpu_info *ci)
+{
+    uint32_t unused, ebx;
+
+    /* Extended features */
+    CPUID(0x07, unused, ebx, unused, unused);
+    if (ISSET(ebx, BIT(7)))
+        ci->feat |= CPU_FEAT_SMEP;
+    if (ISSET(ebx, BIT(20)))
+        ci->feat |= CPU_FEAT_SMAP;
+}
+
 void
 cpu_shootdown_tlb(vaddr_t va)
 {
@@ -304,6 +317,7 @@ void
 cpu_startup(struct cpu_info *ci)
 {
     ci->self = ci;
+    ci->feat = 0;
     gdt_load();
     idt_load();
 
@@ -313,6 +327,8 @@ cpu_startup(struct cpu_info *ci)
     init_tss(ci);
     try_mitigate_spectre();
 
+    cpu_check_feat(ci);
+
     enable_simd();
     lapic_init();
 
diff --git a/sys/include/arch/amd64/cpu.h b/sys/include/arch/amd64/cpu.h
index 2d08d6e..fe8fc8a 100644
--- a/sys/include/arch/amd64/cpu.h
+++ b/sys/include/arch/amd64/cpu.h
@@ -38,8 +38,13 @@
 
 #define CPU_IRQ(IRQ_N) (BIT((IRQ_N)) & 0xFF)
 
+/* Feature bits */
+#define CPU_FEAT_SMAP  BIT(0)
+#define CPU_FEAT_SMEP  BIT(1)
+
 struct cpu_info {
     uint32_t apicid;
+    uint32_t feat;
     uint8_t has_x2apic : 1;
     uint8_t tlb_shootdown : 1;
     uint8_t ipl;