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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-18 18:50:36 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-18 18:50:36 +0000
commit50ba0232fd5312410f1b65247e774244f89a628e (patch)
treefd8f2fc78e9e548af0ff9590276602ee6125be00 /arch/riscv/include/asm/archrandom.h
parentReleasing progress-linux version 6.7.12-1~progress7.99u1. (diff)
downloadlinux-50ba0232fd5312410f1b65247e774244f89a628e.tar.xz
linux-50ba0232fd5312410f1b65247e774244f89a628e.zip
Merging upstream version 6.8.9.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/riscv/include/asm/archrandom.h')
-rw-r--r--arch/riscv/include/asm/archrandom.h72
1 files changed, 72 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/archrandom.h b/arch/riscv/include/asm/archrandom.h
new file mode 100644
index 0000000000..5345360adf
--- /dev/null
+++ b/arch/riscv/include/asm/archrandom.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Kernel interface for the RISCV arch_random_* functions
+ *
+ * Copyright (c) 2023 Rivos Inc.
+ *
+ */
+
+#ifndef ASM_RISCV_ARCHRANDOM_H
+#define ASM_RISCV_ARCHRANDOM_H
+
+#include <asm/csr.h>
+#include <asm/processor.h>
+
+#define SEED_RETRY_LOOPS 100
+
+static inline bool __must_check csr_seed_long(unsigned long *v)
+{
+ unsigned int retry = SEED_RETRY_LOOPS, valid_seeds = 0;
+ const int needed_seeds = sizeof(long) / sizeof(u16);
+ u16 *entropy = (u16 *)v;
+
+ do {
+ /*
+ * The SEED CSR must be accessed with a read-write instruction.
+ */
+ unsigned long csr_seed = csr_swap(CSR_SEED, 0);
+ unsigned long opst = csr_seed & SEED_OPST_MASK;
+
+ switch (opst) {
+ case SEED_OPST_ES16:
+ entropy[valid_seeds++] = csr_seed & SEED_ENTROPY_MASK;
+ if (valid_seeds == needed_seeds)
+ return true;
+ break;
+
+ case SEED_OPST_DEAD:
+ pr_err_once("archrandom: Unrecoverable error\n");
+ return false;
+
+ case SEED_OPST_BIST:
+ case SEED_OPST_WAIT:
+ default:
+ cpu_relax();
+ continue;
+ }
+ } while (--retry);
+
+ return false;
+}
+
+static inline size_t __must_check arch_get_random_longs(unsigned long *v, size_t max_longs)
+{
+ return 0;
+}
+
+static inline size_t __must_check arch_get_random_seed_longs(unsigned long *v, size_t max_longs)
+{
+ if (!max_longs)
+ return 0;
+
+ /*
+ * If Zkr is supported and csr_seed_long succeeds, we return one long
+ * worth of entropy.
+ */
+ if (riscv_has_extension_likely(RISCV_ISA_EXT_ZKR) && csr_seed_long(v))
+ return 1;
+
+ return 0;
+}
+
+#endif /* ASM_RISCV_ARCHRANDOM_H */