linux-dev/arch/x86/kernel/fpu/regset.c, branch linus/master

x86/ptrace: Fix xfpregs_set()'s incorrect xmm clearing

2022-02-18T10:23:21Z

xfpregs_set() handles 32-bit REGSET_XFP and 64-bit REGSET_FP. The actual code treats these regsets as modern FX state (i.e. the beginning part of XSTATE). The declarations of the regsets thought they were the legacy i387 format. The code thought they were the 32-bit (no xmm8..15) variant of XSTATE and, for good measure, made the high bits disappear by zeroing the wrong part of the buffer. The latter broke ptrace, and everything else confused anyone trying to understand the code. In particular, the nonsense definitions of the regsets confused me when I wrote this code. Clean this all up. Change the declarations to match reality (which shouldn't change the generated code, let alone the ABI) and fix xfpregs_set() to clear the correct bits and to only do so for 32-bit callers. Fixes: 6164331d15f7 ("x86/fpu: Rewrite xfpregs_set()") Reported-by: Luís Ferreira Signed-off-by: Andy Lutomirski Signed-off-by: Borislav Petkov Cc: Link: https://bugzilla.kernel.org/show_bug.cgi?id=215524 Link: https://lore.kernel.org/r/YgpFnZpF01WwR8wU@zn.tnic

x86/fpu: Move xstate size to fpu_*_cfg

2021-10-21T17:38:55Z

Use the new kernel and user space config storage to store and retrieve the XSTATE buffer sizes. The default and the maximum size are the same for now, but will change when support for dynamically enabled features is added. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211014230739.296830097@linutronix.de

x86/fpu/xstate: Use fpstate for copy_uabi_to_xstate()

2021-10-21T12:24:14Z

Prepare for dynamically enabled states per task. The function needs to retrieve the features and sizes which are valid in a fpstate context. Retrieve them from fpstate. Move the function declarations to the core header as they are not required anywhere else. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211013145323.233529986@linutronix.de

x86/fpu/regset: Convert to fpstate

2021-10-20T20:35:29Z

Convert regset related code to the new register storage mechanism in preparation for dynamically sized buffers. No functional change. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211013145322.555239736@linutronix.de

x86/fpu: Replace the includes of fpu/internal.h

2021-10-20T13:27:29Z

Now that the file is empty, fixup all references with the proper includes and delete the former kitchen sink. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211015011540.001197214@linutronix.de

x86/fpu: Move mxcsr related code to core

2021-10-20T13:27:28Z

No need to expose that to code which only needs the XCR0 accessors. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211015011539.740012411@linutronix.de

x86/fpu: Move fpregs_restore_userregs() to core

2021-10-20T13:27:28Z

Only used internally in the FPU core code. While at it, convert to the percpu accessors which verify preemption is disabled. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211015011539.686806639@linutronix.de

x86/fpu: Clean up CPU feature tests

2021-10-20T13:27:27Z

Further disintegration of internal.h: Move the CPU feature tests to a core header and remove the unused one. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211015011539.401510559@linutronix.de

x86/fpu: Hook up PKRU into ptrace()

2021-06-23T17:44:24Z

One nice thing about having PKRU be XSAVE-managed is that it gets naturally exposed into the XSAVE-using ABIs. Now that XSAVE will not be used to manage PKRU, these ABIs need to be manually enabled to deal with PKRU. ptrace() uses copy_uabi_xstate_to_kernel() to collect the tracee's XSTATE. As PKRU is not in the task's XSTATE buffer, use task->thread.pkru for filling in up the ptrace buffer. Signed-off-by: Dave Hansen Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121456.508770763@linutronix.de

x86/fpu: Rename and sanitize fpu__save/copy()

2021-06-23T16:55:56Z

Both function names are a misnomer. fpu__save() is actually about synchronizing the hardware register state into the task's memory state so that either coredump or a math exception handler can inspect the state at the time where the problem happens. The function guarantees to preserve the register state, while "save" is a common terminology for saving the current state so it can be modified and restored later. This is clearly not the case here. Rename it to fpu_sync_fpstate(). fpu__copy() is used to clone the current task's FPU state when duplicating task_struct. While the register state is a copy the rest of the FPU state is not. Name it accordingly and remove the really pointless @src argument along with the warning which comes along with it. Nothing can ever copy the FPU state of a non-current task. It's clearly just a consequence of arch_dup_task_struct(), but it makes no sense to proliferate that further. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210623121455.196727450@linutronix.de