commit db204d73587b6076b61fafe77a36703cf5d0ecd2
author Ruchika Gupta <ruchika.gupta@nxp.com> Wed Aug 16 15:58:10 2017 +0530
committer Tom Rini <trini@konsulko.com> Sat Aug 26 14:56:11 2017 -0400
tree 56b5e159ab2ae081434ac18dabdb3e281b1094a3
parent a9e5609fa5e636d8bdc35b3d4480c7dcbfb8ab79

ARMv8/sec_firmware : Update chosen/kaslr-seed with random number

kASLR support in kernel requires a random number to be passed via
chosen/kaslr-seed propert. sec_firmware generates this random seed
which can then be passed in the device tree node.

sec_firmware reserves JR3 for it's own usage. Node for JR3 is
removed from device-tree.

Signed-off-by: Ruchika Gupta <ruchika.gupta@nxp.com>

arch/arm/cpu/armv8/sec_firmware.c

diff --git a/arch/arm/cpu/armv8/sec_firmware.c b/arch/arm/cpu/armv8/sec_firmware.c
index fffce71..0e74834 100644
--- a/arch/arm/cpu/armv8/sec_firmware.c
+++ b/arch/arm/cpu/armv8/sec_firmware.c
@@ -232,6 +232,59 @@
 #endif
 
 /*
+ * Check with sec_firmware if it supports random number generation
+ * via HW RNG
+ *
+ * The return value will be true if it is supported
+ */
+bool sec_firmware_support_hwrng(void)
+{
+	uint8_t rand[8];
+	if (sec_firmware_addr & SEC_FIRMWARE_RUNNING) {
+		if (!sec_firmware_get_random(rand, 8))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * sec_firmware_get_random - Get a random number from SEC Firmware
+ * @rand:		random number buffer to be filled
+ * @bytes:		Number of bytes of random number to be supported
+ * @eret:		-1 in case of error, 0 for success
+ */
+int sec_firmware_get_random(uint8_t *rand, int bytes)
+{
+	unsigned long long num;
+	struct pt_regs regs;
+	int param1;
+
+	if (!bytes || bytes > 8) {
+		printf("Max Random bytes genration supported is 8\n");
+		return -1;
+	}
+#define SIP_RNG_64 0xC200FF11
+	regs.regs[0] = SIP_RNG_64;
+
+	if (bytes <= 4)
+		param1 = 0;
+	else
+		param1 = 1;
+	regs.regs[1] = param1;
+
+	smc_call(&regs);
+
+	if (regs.regs[0])
+		return -1;
+
+	num = regs.regs[1];
+	memcpy(rand, &num, bytes);
+
+	return 0;
+}
+
+/*
  * sec_firmware_init - Initialize the SEC Firmware
  * @sec_firmware_img:	the SEC Firmware image address
  * @eret_hold_l:	the address to hold exception return address low
@@ -278,3 +331,49 @@
 
 	return 0;
 }
+
+/*
+ * fdt_fix_kaslr - Add kalsr-seed node in Device tree
+ * @fdt:		Device tree
+ * @eret:		0 in case of error, 1 for success
+ */
+int fdt_fixup_kaslr(void *fdt)
+{
+	int nodeoffset;
+	int err, ret = 0;
+	u8 rand[8];
+
+#if defined(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT)
+	/* Check if random seed generation is  supported */
+	if (sec_firmware_support_hwrng() == false)
+		return 0;
+
+	ret = sec_firmware_get_random(rand, 8);
+	if (ret < 0) {
+		printf("WARNING: No random number to set kaslr-seed\n");
+		return 0;
+	}
+
+	err = fdt_check_header(fdt);
+	if (err < 0) {
+		printf("fdt_chosen: %s\n", fdt_strerror(err));
+		return 0;
+	}
+
+	/* find or create "/chosen" node. */
+	nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
+	if (nodeoffset < 0)
+		return 0;
+
+	err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", rand,
+				  sizeof(rand));
+	if (err < 0) {
+		printf("WARNING: can't set kaslr-seed %s.\n",
+		       fdt_strerror(err));
+		return 0;
+	}
+	ret = 1;
+#endif
+
+	return ret;
+}