From: "tip-bot2 for Thomas Gleixner" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@suse.de>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: x86/fpu] x86/fpu/signal: Split out the direct restore code
Date: Wed, 23 Jun 2021 22:08:51 -0000 [thread overview]
Message-ID: <162448613105.395.13274798746048155095.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210623121457.493455414@linutronix.de>
The following commit has been merged into the x86/fpu branch of tip:
Commit-ID: 0a6c2e9ec91c96bde1e8ce063180ac6e05e680f7
Gitweb: https://git.kernel.org/tip/0a6c2e9ec91c96bde1e8ce063180ac6e05e680f7
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 23 Jun 2021 14:02:29 +02:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Wed, 23 Jun 2021 20:03:44 +02:00
x86/fpu/signal: Split out the direct restore code
Prepare for smarter failure handling of the direct restore.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121457.493455414@linutronix.de
---
arch/x86/kernel/fpu/signal.c | 112 +++++++++++++++++-----------------
1 file changed, 58 insertions(+), 54 deletions(-)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index a1a7013..aa268d9 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -250,10 +250,8 @@ sanitize_restored_user_xstate(union fpregs_state *state,
}
}
-/*
- * Restore the FPU state directly from the userspace signal frame.
- */
-static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only)
+static int __restore_fpregs_from_user(void __user *buf, u64 xrestore,
+ bool fx_only)
{
if (use_xsave()) {
u64 init_bv = xfeatures_mask_uabi() & ~xrestore;
@@ -274,6 +272,57 @@ static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only
}
}
+static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only)
+{
+ struct fpu *fpu = ¤t->thread.fpu;
+ int ret;
+
+ fpregs_lock();
+ pagefault_disable();
+ ret = __restore_fpregs_from_user(buf, xrestore, fx_only);
+ pagefault_enable();
+
+ if (unlikely(ret)) {
+ /*
+ * The above did an FPU restore operation, restricted to
+ * the user portion of the registers, and failed, but the
+ * microcode might have modified the FPU registers
+ * nevertheless.
+ *
+ * If the FPU registers do not belong to current, then
+ * invalidate the FPU register state otherwise the task
+ * might preempt current and return to user space with
+ * corrupted FPU registers.
+ *
+ * In case current owns the FPU registers then no further
+ * action is required. The fixup in the slow path will
+ * handle it correctly.
+ */
+ if (test_thread_flag(TIF_NEED_FPU_LOAD))
+ __cpu_invalidate_fpregs_state();
+ fpregs_unlock();
+ return ret;
+ }
+
+ /*
+ * Restore supervisor states: previous context switch etc has done
+ * XSAVES and saved the supervisor states in the kernel buffer from
+ * which they can be restored now.
+ *
+ * It would be optimal to handle this with a single XRSTORS, but
+ * this does not work because the rest of the FPU registers have
+ * been restored from a user buffer directly. The single XRSTORS
+ * happens below, when the user buffer has been copied to the
+ * kernel one.
+ */
+ if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor())
+ os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor());
+
+ fpregs_mark_activate();
+ fpregs_unlock();
+ return 0;
+}
+
static int __fpu_restore_sig(void __user *buf, void __user *buf_fx,
bool ia32_fxstate)
{
@@ -298,61 +347,16 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx,
user_xfeatures = fx_sw_user.xfeatures;
}
- if (!ia32_fxstate) {
+ if (likely(!ia32_fxstate)) {
/*
* Attempt to restore the FPU registers directly from user
- * memory. For that to succeed, the user access cannot cause
- * page faults. If it does, fall back to the slow path below,
- * going through the kernel buffer with the enabled pagefault
- * handler.
+ * memory. For that to succeed, the user access cannot cause page
+ * faults. If it does, fall back to the slow path below, going
+ * through the kernel buffer with the enabled pagefault handler.
*/
- fpregs_lock();
- pagefault_disable();
ret = restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only);
- pagefault_enable();
- if (!ret) {
-
- /*
- * Restore supervisor states: previous context switch
- * etc has done XSAVES and saved the supervisor states
- * in the kernel buffer from which they can be restored
- * now.
- *
- * We cannot do a single XRSTORS here - which would
- * be nice - because the rest of the FPU registers are
- * being restored from a user buffer directly. The
- * single XRSTORS happens below, when the user buffer
- * has been copied to the kernel one.
- */
- if (test_thread_flag(TIF_NEED_FPU_LOAD) &&
- xfeatures_mask_supervisor()) {
- os_xrstor(&fpu->state.xsave,
- xfeatures_mask_supervisor());
- }
- fpregs_mark_activate();
- fpregs_unlock();
+ if (likely(!ret))
return 0;
- }
-
- /*
- * The above did an FPU restore operation, restricted to
- * the user portion of the registers, and failed, but the
- * microcode might have modified the FPU registers
- * nevertheless.
- *
- * If the FPU registers do not belong to current, then
- * invalidate the FPU register state otherwise the task might
- * preempt current and return to user space with corrupted
- * FPU registers.
- *
- * In case current owns the FPU registers then no further
- * action is required. The fixup below will handle it
- * correctly.
- */
- if (test_thread_flag(TIF_NEED_FPU_LOAD))
- __cpu_invalidate_fpregs_state();
-
- fpregs_unlock();
} else {
/*
* For 32-bit frames with fxstate, copy the fxstate so it can
next prev parent reply other threads:[~2021-06-23 22:08 UTC|newest]
Thread overview: 142+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 12:01 [patch V4 00/65] x86/fpu: Spring cleaning and PKRU sanitizing Thomas Gleixner
2021-06-23 12:01 ` [patch V4 01/65] x86/fpu: Fix copy_xstate_to_kernel() gap handling Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 02/65] x86/pkeys: Revert a5eff7259790 ("x86/pkeys: Add PKRU value to init_fpstate") Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 03/65] x86/fpu: Mark various FPU states __ro_after_init Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] x86/fpu: Mark various FPU state variables __ro_after_init tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 04/65] x86/fpu: Make xfeatures_mask_all __ro_after_init Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 05/65] x86/fpu: Get rid of fpu__get_supported_xfeatures_mask() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 06/65] x86/fpu: Remove unused get_xsave_field_ptr() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 07/65] x86/fpu: Move inlines where they belong Thomas Gleixner
2021-06-23 18:43 ` Bae, Chang Seok
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 08/65] x86/fpu: Limit xstate copy size in xstateregs_set() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 09/65] x86/fpu: Sanitize xstateregs_set() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2022-07-14 4:04 ` [patch V4 09/65] " Andrei Vagin
2022-07-25 17:47 ` Dave Hansen
2022-07-25 17:57 ` Andrei Vagin
2022-07-25 21:26 ` Dave Hansen
2022-07-28 23:32 ` Chang S. Bae
2022-08-05 12:12 ` Andrei Vagin
2022-08-05 18:24 ` Chang S. Bae
2022-08-05 18:35 ` Dave Hansen
2021-06-23 12:01 ` [patch V4 10/65] x86/fpu: Reject invalid MXCSR values in copy_kernel_to_xstate() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 11/65] x86/fpu: Simplify PTRACE_GETREGS code Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Dave Hansen
2021-06-23 12:01 ` [patch V4 12/65] x86/fpu: Rewrite xfpregs_set() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Andy Lutomirski
2021-06-23 12:01 ` [patch V4 13/65] x86/fpu: Fail ptrace() requests that try to set invalid MXCSR values Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Andy Lutomirski
2021-06-23 12:01 ` [patch V4 14/65] x86/fpu: Clean up fpregs_set() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Andy Lutomirski
2021-06-23 12:01 ` [patch V4 15/65] x86/fpu: Make copy_xstate_to_kernel() usable for [x]fpregs_get() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-24 15:09 ` [PATCH] x86/fpu/xstate: Clear xstate header in copy_xstate_to_uabi_buf() again Thomas Gleixner
2021-06-24 15:41 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 16/65] x86/fpu: Use copy_xstate_to_uabi_buf() in xfpregs_get() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 17/65] x86/fpu: Use copy_xstate_to_uabi_buf() in fpregs_get() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 18/65] x86/fpu: Remove fpstate_sanitize_xstate() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 19/65] x86/fpu/regset: Move fpu__read_begin() into regset Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 20/65] x86/fpu: Move fpu__write_begin() to regset Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 21/65] x86/fpu: Get rid of using_compacted_format() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 22/65] x86/kvm: Avoid looking up PKRU in XSAVE buffer Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Dave Hansen
2021-06-23 12:01 ` [patch V4 23/65] x86/fpu: Cleanup arch_set_user_pkey_access() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 24/65] x86/fpu: Get rid of copy_supervisor_to_kernel() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 25/65] x86/fpu: Rename copy_xregs_to_kernel() and copy_kernel_to_xregs() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 26/65] x86/fpu: Rename copy_user_to_xregs() and copy_xregs_to_user() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 27/65] x86/fpu: Rename fxregs related copy functions Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] x86/fpu: Rename fxregs-related " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 28/65] x86/math-emu: Rename frstor() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 29/65] x86/fpu: Rename fregs related copy functions Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] x86/fpu: Rename fregs-related " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 30/65] x86/fpu: Rename xstate copy functions which are related to UABI Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 31/65] x86/fpu: Deduplicate copy_uabi_from_user/kernel_to_xstate() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:01 ` [patch V4 32/65] x86/fpu: Rename copy_fpregs_to_fpstate() to save_fpregs_to_fpstate() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 33/65] x86/fpu: Get rid of the FNSAVE optimization Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 34/65] x86/fpu: Rename copy_kernel_to_fpregs() to restore_fpregs_from_fpstate() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 35/65] x86/fpu: Rename initstate copy functions Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 36/65] x86/fpu: Rename "dynamic" XSTATEs to "independent" Thomas Gleixner
2021-06-23 12:02 ` [patch V4 37/65] x86/fpu/xstate: Sanitize handling of independent features Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 38/65] x86/pkeys: Move read_pkru() and write_pkru() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Dave Hansen
2021-06-23 12:02 ` [patch V4 39/65] x86/fpu: Rename and sanitize fpu__save/copy() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 40/65] x86/cpu: Sanitize X86_FEATURE_OSPKE Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 41/65] x86/pkru: Provide pkru_get_init_value() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 42/65] x86/pkru: Provide pkru_write_default() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 43/65] x86/cpu: Write the default PKRU value when enabling PKE Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 44/65] x86/fpu: Use pkru_write_default() in copy_init_fpstate_to_fpregs() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 45/65] x86/fpu: Rename fpu__clear_all() to fpu_flush_thread() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 46/65] x86/fpu: Clean up the fpu__clear() variants Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Andy Lutomirski
2021-06-23 12:02 ` [patch V4 47/65] x86/fpu: Rename __fpregs_load_activate() to fpregs_restore_userregs() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 48/65] x86/fpu: Move FXSAVE_LEAK quirk info __copy_kernel_to_fpregs() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 49/65] x86/fpu: Rename xfeatures_mask_user() to xfeatures_mask_uabi() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 50/65] x86/fpu: Dont restore PKRU in fpregs_restore_userspace() Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 51/65] x86/fpu: Add PKRU storage outside of task XSAVE buffer Thomas Gleixner
2021-06-23 22:09 ` [tip: x86/fpu] " tip-bot2 for Dave Hansen
2021-06-23 12:02 ` [patch V4 52/65] x86/fpu: Hook up PKRU into ptrace() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Dave Hansen
2021-06-23 12:02 ` [patch V4 53/65] x86/fpu: Mask PKRU from kernel XRSTOR[S] operations Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 54/65] x86/fpu: Remove PKRU handling from switch_fpu_finish() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 55/65] x86/fpu: Dont store PKRU in xstate in fpu_reset_fpstate() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] x86/fpu: Don't " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 56/65] x86/pkru: Remove xstate fiddling from write_pkru() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 57/65] x86/fpu: Mark init_fpstate __ro_after_init Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 58/65] x86/fpu/signal: Move initial checks into fpu__sig_restore() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] x86/fpu/signal: Move initial checks into fpu__restore_sig() tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 59/65] x86/fpu/signal: Remove the legacy alignment check Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 60/65] x86/fpu/signal: Sanitize the xstate check on sigframe Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 61/65] x86/fpu/signal: Sanitize copy_user_to_fpregs_zeroing() Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 62/65] x86/fpu/signal: Split out the direct restore code Thomas Gleixner
2021-06-23 22:08 ` tip-bot2 for Thomas Gleixner [this message]
2021-06-23 12:02 ` [patch V4 63/65] x86/fpu: Return proper error codes from user access functions Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 64/65] x86/fpu/signal: Handle #PF in the direct restore path Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-23 12:02 ` [patch V4 65/65] x86/fpu/signal: Let xrstor handle the features to init Thomas Gleixner
2021-06-23 22:08 ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-06-25 14:50 ` [patch V4 00/65] x86/fpu: Spring cleaning and PKRU sanitizing Oliver Sang
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