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backport new FPU register copy helpers

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This allows us to fix the ZFS SIMD patch for 5.0 kernel way easier.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Thomas Lamprecht 2019-09-27 11:27:56 +02:00
parent 97f24aae50
commit 0570f90d28
1 changed files with 103 additions and 0 deletions
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103
patches/kernel/0007-x86-fpu-backport-copy_kernel_to_XYZ_err-helpers.patch Normal file
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@ -0,0 +1,103 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Wed, 3 Apr 2019 18:41:50 +0200
Subject: [PATCH] x86/fpu: backport copy_kernel_to_XYZ_err helpers
MIME-Version: 1.0
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partial cherry-pick from upstream 5.2 "86/fpu: Restore from kernel
memory on the 64-bit path too"
commit 926b21f37b072ae4c117052de45a975c6d468fec
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Namely, only backport the added helpers, none of the semantic changes.
relevant parts of the original commit message:
> In order to avoid that mess, copy the FPU state from userland, validate
> it and then load it. The copy_kernel_…() helpers are basically just
> like the old helpers except that they operate on kernel memory and the
> fault handler just sets the error value and the caller handles it.
Link: https://lkml.kernel.org/r/20190403164156.19645-22-bigeasy@linutronix.de
(partial cherry picked from commit 926b21f37b072ae4c117052de45a975c6d468fec)
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
arch/x86/include/asm/fpu/internal.h | 43 +++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index fa2c93cb42a2..f3193ab0a2fb 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -122,6 +122,21 @@ extern void fpstate_sanitize_xstate(struct fpu *fpu);
err; \
})
+#define kernel_insn_err(insn, output, input...) \
+({ \
+ int err; \
+ asm volatile("1:" #insn "\n\t" \
+ "2:\n" \
+ ".section .fixup,\"ax\"\n" \
+ "3: movl $-1,%[err]\n" \
+ " jmp 2b\n" \
+ ".previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : [err] "=r" (err), output \
+ : "0"(0), input); \
+ err; \
+})
+
#define kernel_insn(insn, output, input...) \
asm volatile("1:" #insn "\n\t" \
"2:\n" \
@@ -158,6 +173,14 @@ static inline void copy_kernel_to_fxregs(struct fxregs_state *fx)
}
}
+static inline int copy_kernel_to_fxregs_err(struct fxregs_state *fx)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return kernel_insn_err(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ else
+ return kernel_insn_err(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
{
if (IS_ENABLED(CONFIG_X86_32))
@@ -175,6 +198,11 @@ static inline void copy_kernel_to_fregs(struct fregs_state *fx)
kernel_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
}
+static inline int copy_kernel_to_fregs_err(struct fregs_state *fx)
+{
+ return kernel_insn_err(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+}
+
static inline int copy_user_to_fregs(struct fregs_state __user *fx)
{
return user_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
@@ -400,6 +428,21 @@ static inline int copy_user_to_xregs(struct xregs_state __user *buf, u64 mask)
return err;
}
+/*
+ * Restore xstate from kernel space xsave area, return an error code instead of
+ * an exception.
+ */
+static inline int copy_kernel_to_xregs_err(struct xregs_state *xstate, u64 mask)
+{
+ u32 lmask = mask;
+ u32 hmask = mask >> 32;
+ int err;
+
+ XSTATE_OP(XRSTOR, xstate, lmask, hmask, err);
+
+ return err;
+}
+
/*
* These must be called with preempt disabled. Returns
* 'true' if the FPU state is still intact and we can