The protection keys register (PKRU) is saved and restored using
xsave. Define the data structure that we will use to access it
inside the xsave buffer, and also double-check that the new
structure matches the size that comes out of the CPU.
---
b/arch/x86/include/asm/processor.h | 9 +++++++++
b/arch/x86/include/asm/xsave.h | 3 ++-
b/arch/x86/kernel/xsave.c | 7 +++++++
3 files changed, 18 insertions(+), 1 deletion(-)
diff -puN arch/x86/include/asm/processor.h~pkeys-2-xsave
arch/x86/include/asm/processor.h
--- a/arch/x86/include/asm/processor.h~pkeys-2-xsave 2015-05-07
10:31:41.756204056 -0700
+++ b/arch/x86/include/asm/processor.h 2015-05-07 10:31:41.763204372 -0700
@@ -406,6 +406,15 @@ struct bndcsr {
u64 bndstatus;
} __packed;
+/*
+ * "The size of XSAVE state component for PKRU is 8 bytes,
+ * of which only the first four bytes are used...".
+ */
+struct pkru {
+ u32 pkru;
+ u32 pkru_unused;
+} __packed;
+
struct xsave_hdr_struct {
u64 xstate_bv;
u64 xcomp_bv;
diff -puN arch/x86/include/asm/xsave.h~pkeys-2-xsave
arch/x86/include/asm/xsave.h
--- a/arch/x86/include/asm/xsave.h~pkeys-2-xsave 2015-05-07
10:31:41.758204147 -0700
+++ b/arch/x86/include/asm/xsave.h 2015-05-07 10:31:41.764204417 -0700
@@ -14,6 +14,7 @@
#define XSTATE_OPMASK 0x20
#define XSTATE_ZMM_Hi256 0x40
#define XSTATE_Hi16_ZMM 0x80
+#define XSTATE_PKRU 0x200
#define XSTATE_FPSSE (XSTATE_FP | XSTATE_SSE)
#define XSTATE_AVX512 (XSTATE_OPMASK | XSTATE_ZMM_Hi256 | XSTATE_Hi16_ZMM)
@@ -33,7 +34,7 @@
| XSTATE_OPMASK | XSTATE_ZMM_Hi256 | XSTATE_Hi16_ZMM)
/* Supported features which require eager state saving */
-#define XSTATE_EAGER (XSTATE_BNDREGS | XSTATE_BNDCSR)
+#define XSTATE_EAGER (XSTATE_BNDREGS | XSTATE_BNDCSR | XSTATE_PKRU)
/* All currently supported features */
#define XCNTXT_MASK (XSTATE_LAZY | XSTATE_EAGER)
diff -puN arch/x86/kernel/xsave.c~pkeys-2-xsave arch/x86/kernel/xsave.c
--- a/arch/x86/kernel/xsave.c~pkeys-2-xsave 2015-05-07 10:31:41.760204237
-0700
+++ b/arch/x86/kernel/xsave.c 2015-05-07 10:31:41.764204417 -0700
@@ -528,6 +528,13 @@ void setup_xstate_comp(void)
+ xstate_comp_sizes[i-1];
}
+ /*
+ * Check that the size of the "PKRU" xsave area
+ * which the CPU knows about matches the kernel
+ * data structure that we have defined.
+ */
+ if ((xstate_features >= XSTATE_PKRU) && xstate_comp_sizes[XSTATE_PKRU])
+ WARN_ON(xstate_comp_sizes[XSTATE_PKRU] != sizeof(struct pkru));
}
/*
_
--
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