Decoupling Architectural-specific Code (#35)

[lunaix-os.git] / lunaix-os / arch / i386 / hal / rngx86.c

diff --git a/lunaix-os/arch/i386/hal/rngx86.c b/lunaix-os/arch/i386/hal/rngx86.c
new file mode 100644 (file)
index 0000000..b108740
--- /dev/null
+++ b/lunaix-os/arch/i386/hal/rngx86.c
@@ -0,0 +1,56 @@
+#include <lunaix/device.h>
+#include <lunaix/mm/pagetable.h>
+
+#include <klibc/string.h>
+
+static inline void
+rng_fill(void* data, size_t len)
+{
+    asm volatile("1:\n"
+                 "rdrand %%eax\n"
+                 "movl %%eax, (%0)\n"
+                 "addl $4, %%eax\n"
+                 "subl $4, %1\n"
+                 "jnz 1b" ::"r"((ptr_t)data),
+                 "r"((len & ~0x3))
+                 : "%eax");
+}
+
+static int
+__rand_rd_pg(struct device* dev, void* buf, size_t offset)
+{
+    rng_fill(buf, PAGE_SIZE);
+    return PAGE_SIZE;
+}
+
+static int
+__rand_rd(struct device* dev, void* buf, size_t offset, size_t len)
+{
+    if (unlikely(len < 4)) {
+        int tmp_buf = 0;
+        rng_fill(&tmp_buf, 4);
+        memcpy(buf, &tmp_buf, len);
+    } else {
+        rng_fill(buf, len);
+    }
+    return len;
+}
+
+int
+pdev_randdev_init(struct device_def* devdef)
+{
+    // FIXME add check on cpuid for presence of rdrand
+    struct device* devrand = device_allocseq(NULL, NULL);
+    devrand->ops.read = __rand_rd;
+    devrand->ops.read_page = __rand_rd_pg;
+
+    register_device(devrand, &devdef->class, "rand");
+
+    return 0;
+}
+
+static struct device_def devrandx86_def = {
+    .name = "x86 On-Chip RNG",
+    .class = DEVCLASS(DEVIF_SOC, DEVFN_CHAR, DEV_RNG),
+    .init = pdev_randdev_init};
+EXPORT_DEVICE(randdev, &devrandx86_def, load_onboot);
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