[PATCH v8 06/38] arm64/sysreg: Add definitions for architected GCS caps

Mark Brown
2024-02-03T12:29:28Z

The architecture defines a format for guarded control stack caps, used
to mark the top of an unused GCS in order to limit the potential for
exploitation via stack switching. Add definitions associated with these.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/sysreg.h | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index c3b19b376c86..6ed813e856c1 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -1064,6 +1064,26 @@
#define POE_RXW UL(0x7)
#define POE_MASK UL(0xf)

+/*
+ * Definitions for Guarded Control Stack
+ */
+
+#define GCS_CAP_ADDR_MASK GENMASK(63, 12)
+#define GCS_CAP_ADDR_SHIFT 12
+#define GCS_CAP_ADDR_WIDTH 52
+#define GCS_CAP_ADDR(x) FIELD_GET(GCS_CAP_ADDR_MASK, x)
+
+#define GCS_CAP_TOKEN_MASK GENMASK(11, 0)
+#define GCS_CAP_TOKEN_SHIFT 0
+#define GCS_CAP_TOKEN_WIDTH 12
+#define GCS_CAP_TOKEN(x) FIELD_GET(GCS_CAP_TOKEN_MASK, x)
+
+#define GCS_CAP_VALID_TOKEN 0x1
+#define GCS_CAP_IN_PROGRESS_TOKEN 0x5
+
+#define GCS_CAP(x) ((((unsigned long)x) & GCS_CAP_ADDR_MASK) | \
+ GCS_CAP_VALID_TOKEN)
+
#define ARM64_FEATURE_FIELD_BITS 4

/* Defined for compatibility only, do not add new users. */

--
2.30.2