- 23 Jun, 2021 36 commits
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Thomas Gleixner authored
Again this not a copy. It's restoring register state from kernel memory. Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210623121454.816581630@linutronix.de
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Thomas Gleixner authored
This is not a copy functionality. It restores the register state from the supplied kernel buffer. No functional changes. Signed-off-by:
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Thomas Gleixner authored
The FNSAVE support requires conditionals in quite some call paths because FNSAVE reinitializes the FPU hardware. If the save has to preserve the FPU register state then the caller has to conditionally restore it from memory when FNSAVE is in use. This also requires a conditional in context switch because the restore avoidance optimization cannot work with FNSAVE. As this only affects 20+ years old CPUs there is really no reason to keep this optimization effective for FNSAVE. It's about time to not optimize for antiques anymore. Just unconditionally FRSTOR the save content to the registers and clean up the conditionals all over the place. Suggested-by:
Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by:
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Thomas Gleixner authored
A copy is guaranteed to leave the source intact, which is not the case when FNSAVE is used as that reinitilizes the registers. Save does not make such guarantees and it matches what this is about, i.e. to save the state for a later restore. Rename it to save_fpregs_to_fpstate(). Signed-off-by:
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Thomas Gleixner authored
copy_uabi_from_user_to_xstate() and copy_uabi_from_kernel_to_xstate() are almost identical except for the copy function. Unify them. Signed-off-by:
Andy Lutomirski <luto@kernel.org> Link: https://lkml.kernel.org/r/20210623121454.414215896@linutronix.de
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Thomas Gleixner authored
Rename them to reflect that these functions deal with user space format XSAVE buffers. copy_kernel_to_xstate() -> copy_uabi_from_kernel_to_xstate() copy_user_to_xstate() -> copy_sigframe_from_user_to_xstate() Again a clear statement that these functions deal with user space ABI. Suggested-by: -
Thomas Gleixner authored
The function names for fnsave/fnrstor operations are horribly named and a permanent source of confusion. Rename: copy_kernel_to_fregs() to frstor() copy_fregs_to_user() to fnsave_to_user_sigframe() copy_user_to_fregs() to frstor_from_user_sigframe() so it's clear what these are doing. All these functions are really low level wrappers around the equally named instructions, so mapping to the documentation is just natural. No functional change. Signed-off-by:
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Thomas Gleixner authored
This is in the way of renaming the low level hardware accessors to match the instruction name. Prepend it with FPU_ which is consistent vs. the rest of the emulation code. No functional change. [ bp: Correct the Reported-by: ] Reported-by:
kernel test robot <lkp@intel.com> Signed-off-by:
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Thomas Gleixner authored
The function names for fxsave/fxrstor operations are horribly named and a permanent source of confusion. Rename: copy_fxregs_to_kernel() to fxsave() copy_kernel_to_fxregs() to fxrstor() copy_fxregs_to_user() to fxsave_to_user_sigframe() copy_user_to_fxregs() to fxrstor_from_user_sigframe() so it's clear what these are doing. All these functions are really low level wrappers around the equally named instructions, so mapping to the documentation is just natural. While at it, replace the static_cpu_has(X86_FEATURE_FXSR) with use_fxsr() to be consistent with the rest of the code. No functional change. Signed-off-by:
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Thomas Gleixner authored
The function names for xsave[s]/xrstor[s] operations are horribly named and a permanent source of confusion. Rename: copy_xregs_to_user() to xsave_to_user_sigframe() copy_user_to_xregs() to xrstor_from_user_sigframe() so it's entirely clear what this is about. This is also a clear indicator of the potentially different storage format because this is user ABI and cannot use compacted format. No functional change. Signed-off-by:
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Thomas Gleixner authored
The function names for xsave[s]/xrstor[s] operations are horribly named and a permanent source of confusion. Rename: copy_xregs_to_kernel() to os_xsave() copy_kernel_to_xregs() to os_xrstor() These are truly low level wrappers around the actual instructions XSAVE[OPT]/XRSTOR and XSAVES/XRSTORS with the twist that the selection based on the available CPU features happens with an alternative to avoid conditionals all over the place and to provide the best performance for hot paths. The os_ prefix tells that this is the OS selected mechanism. No functional change. Signed-off-by:
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Thomas Gleixner authored
If the fast path of restoring the FPU state on sigreturn fails or is not taken and the current task's FPU is active then the FPU has to be deactivated for the slow path to allow a safe update of the tasks FPU memory state. With supervisor states enabled, this requires to save the supervisor state in the memory state first. Supervisor states require XSAVES so saving only the supervisor state requires to reshuffle the memory buffer because XSAVES uses the compacted format and therefore stores the supervisor states at the beginning of the memory state. That's just an overengineered optimization. Get rid of it and save the full state for this case. Signed-off-by:
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Thomas Gleixner authored
The function does a sanity check with a WARN_ON_ONCE() but happily proceeds when the pkey argument is out of range. Clean it up. Signed-off-by:
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Dave Hansen authored
PKRU is being removed from the kernel XSAVE/FPU buffers. This removal will probably include warnings for code that look up PKRU in those buffers. KVM currently looks up the location of PKRU but doesn't even use the pointer that it gets back. Rework the code to avoid calling get_xsave_addr() except in cases where its result is actually used. This makes the code more clear and also avoids the inevitable PKRU warnings. This is probably a good cleanup and could go upstream idependently of any PKRU rework. Signed-off-by:
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Thomas Gleixner authored
This function is pointlessly global and a complete misnomer because it's usage is related to both supervisor state checks and compacted format checks. Remove it and just make the conditions check the XSAVES feature. Signed-off-by:
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Thomas Gleixner authored
The only usecase for fpu__write_begin is the set() callback of regset, so the function is pointlessly global. Move it to the regset code and rename it to fpu_force_restore() which is exactly decribing what the function does. Signed-off-by:
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Thomas Gleixner authored
The function can only be used from the regset get() callbacks safely. So there is no reason to have it globally exposed. Signed-off-by:
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Thomas Gleixner authored
No more users. Signed-off-by:
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Thomas Gleixner authored
Use the new functionality of copy_xstate_to_uabi_buf() to retrieve the FX state when XSAVE* is in use. This avoids to overwrite the FPU state buffer with fpstate_sanitize_xstate() which is error prone and duplicated code. Signed-off-by:
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Thomas Gleixner authored
Use the new functionality of copy_xstate_to_uabi_buf() to retrieve the FX state when XSAVE* is in use. This avoids overwriting the FPU state buffer with fpstate_sanitize_xstate() which is error prone and duplicated code. Signed-off-by:
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Thomas Gleixner authored
When xsave with init state optimization is used then a component's state in the task's xsave buffer can be stale when the corresponding feature bit is not set. fpregs_get() and xfpregs_get() invoke fpstate_sanitize_xstate() to update the task's xsave buffer before retrieving the FX or FP state. That's just duplicated code as copy_xstate_to_kernel() already handles this correctly. Add a copy mode argument to the function which allows to restrict the state copy to the FP and SSE features. Also rename the function to copy_xstate_to_uabi_buf() so the name reflects what it is doing. Signed-off-by:
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Andy Lutomirski authored
fpregs_set() has unnecessary complexity to support short or nonzero-offset writes and to handle the case in which a copy from userspace overwrites some of the target buffer and then fails. Support for partial writes is useless -- just require that the write has offset 0 and the correct size, and copy into a temporary kernel buffer to avoid clobbering the state if the user access fails. Signed-off-by:
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Andy Lutomirski authored
There is no benefit from accepting and silently changing an invalid MXCSR value supplied via ptrace(). Instead, return -EINVAL on invalid input. Signed-off-by:
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Andy Lutomirski authored
xfpregs_set() was incomprehensible. Almost all of the complexity was due to trying to support nonsensically sized writes or -EFAULT errors that would have partially or completely overwritten the destination before failing. Nonsensically sized input would only have been possible using PTRACE_SETREGSET on REGSET_XFP. Fortunately, it appears (based on Debian code search results) that no one uses that API at all, let alone with the wrong sized buffer. Failed user access can be handled more cleanly by first copying to kernel memory. Just rewrite it to require sensible input. Signed-off-by:
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Dave Hansen authored
ptrace() has interfaces that let a ptracer inspect a ptracee's register state. This includes XSAVE state. The ptrace() ABI includes a hardware-format XSAVE buffer for both the SETREGS and GETREGS interfaces. In the old days, the kernel buffer and the ptrace() ABI buffer were the same boring non-compacted format. But, since the advent of supervisor states and the compacted format, the kernel buffer has diverged from the format presented in the ABI. This leads to two paths in the kernel: 1. Effectively a verbatim copy_to_user() which just copies the kernel buffer out to userspace. This is used when the kernel buffer is kept in the non-compacted form which means that it shares a format with the ptrace ABI. 2. A one-state-at-a-time path: copy_xstate_to_kernel(). This is theoretically slower since it does a bunch of piecemeal copies. Remove the verbatim copy case. Speed probably does not matter in this path, and the vast majority of new hardware will use the one-state-at-a-time path anyway. This ensures greater testing for the "slow" path. This also makes enabling PKRU in this interface easier since a single path can be patched instead of two. Signed-off-by:
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Thomas Gleixner authored
Instead of masking out reserved bits, check them and reject the provided state as invalid if not zero. Suggested-by:
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Thomas Gleixner authored
xstateregs_set() operates on a stopped task and tries to copy the provided buffer into the task's fpu.state.xsave buffer. Any error while copying or invalid state detected after copying results in wiping the target task's FPU state completely including supervisor states. That's just wrong. The caller supplied invalid data or has a problem with unmapped memory, so there is absolutely no justification to corrupt the target state. Fix this with the following modifications: 1) If data has to be copied from userspace, allocate a buffer and copy from user first. 2) Use copy_kernel_to_xstate() unconditionally so that header checking works correctly. 3) Return on error without corrupting the target state. This prevents corrupting states and lets the caller deal with the problem it caused in the first place. Signed-off-by: -
Thomas Gleixner authored
If the count argument is larger than the xstate size, this will happily copy beyond the end of xstate. Fixes: 91c3dba7 ("x86/fpu/xstate: Fix PTRACE frames for XSAVES") Signed-off-by:
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Thomas Gleixner authored
They are only used in fpstate_init() and there is no point to have them in a header just to make reading the code harder. Signed-off-by:
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Thomas Gleixner authored
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Thomas Gleixner authored
This function is really not doing what the comment advertises: "Find supported xfeatures based on cpu features and command-line input. This must be called after fpu__init_parse_early_param() is called and xfeatures_mask is enumerated." fpu__init_parse_early_param() does not exist anymore and the function just returns a constant. Remove it and fix the caller and get rid of further references to fpu__init_parse_early_param(). Signed-off-by:
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Thomas Gleixner authored
Nothing has to modify this after init. But of course there is code which unconditionally masks xfeatures_mask_all on CPU hotplug. This goes unnoticed during boot hotplug because at that point the variable is still RW mapped. This is broken in several ways: 1) Masking this in post init CPU hotplug means that any modification of this state goes unnoticed until actual hotplug happens. 2) If that ever happens then these bogus feature bits are already populated all over the place and the system is in inconsistent state vs. the compacted XSTATE offsets. If at all then this has to panic the machine because the inconsistency cannot be undone anymore. Make this a one-time paranoia check in xstate init code and disable xsave when this happens. Reported-by:Kan Liang <kan.liang@linux.intel.com> Signed-off-by:
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Thomas Gleixner authored
Nothing modifies these after booting. Signed-off-by:
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Thomas Gleixner authored
This cannot work and it's unclear how that ever made a difference. init_fpstate.xsave.header.xfeatures is always 0 so get_xsave_addr() will always return a NULL pointer, which will prevent storing the default PKRU value in init_fpstate. Signed-off-by:
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Thomas Gleixner authored
The gap handling in copy_xstate_to_kernel() is wrong when XSAVES is in use. Using init_fpstate for copying the init state of features which are not set in the xstate header is only correct for the legacy area, but not for the extended features area because when XSAVES is in use then init_fpstate is in compacted form which means the xstate offsets which are used to copy from init_fpstate are not valid. Fortunately, this is not a real problem today because all extended features in use have an all-zeros init state, but it is wrong nevertheless and with a potentially dynamically sized init_fpstate this would result in an access outside of the init_fpstate. Fix this by keeping track of the last copied state in the target buffer and explicitly zero it when there is a feature or alignment gap. Use the compacted offset when accessing the extended feature space in init_fpstate. As this is not a functional issue on older kernels this is intentionally not tagged for stable. Fixes: b8be15d5 ("x86/fpu/xstate: Re-enable XSAVES") Signed-off-by:
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Borislav Petkov authored
Pick up dependent changes which either went mainline (x86/urgent is based on -rc7 and that contains them) as urgent fixes and the current x86/urgent branch which contains two more urgent fixes, so that the bigger FPU rework can base off ontop. Signed-off-by:
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- 22 Jun, 2021 2 commits
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Thomas Gleixner authored
The XSAVE init code initializes all enabled and supported components with XRSTOR(S) to init state. Then it XSAVEs the state of the components back into init_fpstate which is used in several places to fill in the init state of components. This works correctly with XSAVE, but not with XSAVEOPT and XSAVES because those use the init optimization and skip writing state of components which are in init state. So init_fpstate.xsave still contains all zeroes after this operation. There are two ways to solve that: 1) Use XSAVE unconditionally, but that requires to reshuffle the buffer when XSAVES is enabled because XSAVES uses compacted format. 2) Save the components which are known to have a non-zero init state by other means. Looking deeper, #2 is the right thing to do because all components the kernel supports have all-zeroes init state except the legacy features (FP, SSE). Those cannot be hard coded because the states are not identical on all CPUs, but they can be saved with FXSAVE which avoids all conditionals. Use FXSAVE to save the legacy FP/SSE components in init_fpstate along with a BUILD_BUG_ON() which reminds developers to validate that a newly added component has all zeroes init state. As a bonus remove the now unused copy_xregs_to_kernel_booting() crutch. The XSAVE and reshuffle method can still be implemented in the unlikely case that components are added which have a non-zero init state and no other means to save them. For now, FXSAVE is just simple and good enough. [ bp: Fix a typo or two in the text. ] Fixes: 6bad06b7 ("x86, xsave: Use xsaveopt in context-switch path when supported") Signed-off-by: -
Thomas Gleixner authored
sanitize_restored_user_xstate() preserves the supervisor states only when the fx_only argument is zero, which allows unprivileged user space to put supervisor states back into init state. Preserve them unconditionally. [ bp: Fix a typo or two in the text. ] Fixes: 5d6b6a6f ("x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates") Signed-off-by:
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- 20 Jun, 2021 2 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull scheduler fix from Borislav Petkov: "A single fix to restore fairness between control groups with equal priority" * tag 'sched_urgent_for_v5.13_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Correctly insert cfs_rq's to list on unthrottle
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