[PATCH v7 3/6] x86/fpu: Add a pkru argument to copy_uabi_to_xstate()

From: Kyle Huey
Date: Tue Nov 15 2022 - 18:12:18 EST


In preparation for moving PKRU handling code out of
fpu_copy_uabi_to_guest_fpstate() and into copy_uabi_to_xstate(), add an
argument that copy_uabi_from_kernel_to_xstate() can use to pass the
canonical location of the PKRU value. For
copy_sigframe_from_user_to_xstate() the kernel will actually restore the
PKRU value from the fpstate, but pass in the thread_struct's pkru location
anyways for consistency.

Signed-off-by: Kyle Huey <me@xxxxxxxxxxxx>
---
arch/x86/kernel/fpu/xstate.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index a4d24ae66796..3a6ced76e932 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1200,8 +1200,18 @@ static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
}


+/**
+ * copy_uabi_to_xstate - Copy a UABI format buffer to the kernel xstate
+ * @fpstate: The fpstate buffer to copy to
+ * @kbuf: The UABI format buffer, if it comes from the kernel
+ * @ubuf: The UABI format buffer, if it comes from userspace
+ * @pkru: unused
+ *
+ * Converts from the UABI format into the kernel internal hardware
+ * dependent format.
+ */
static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
- const void __user *ubuf)
+ const void __user *ubuf, u32 *pkru)
{
struct xregs_state *xsave = &fpstate->regs.xsave;
unsigned int offset, size;
@@ -1270,7 +1280,7 @@ static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
*/
int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
{
- return copy_uabi_to_xstate(fpstate, kbuf, NULL);
+ return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru);
}

/*
@@ -1281,7 +1291,7 @@ int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u
int copy_sigframe_from_user_to_xstate(struct task_struct *tsk,
const void __user *ubuf)
{
- return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf);
+ return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru);
}

static bool validate_independent_components(u64 mask)
--
2.38.1