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Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods

From Thomas Gleixner <tglx@linutronix.de>
Newsgroups linux.kernel
Subject Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods
Date 2017-09-25 22:00 +0200
Message-ID <utHHQ-2sG-23@gated-at.bofh.it> (permalink)
References <usSlX-3wU-3@gated-at.bofh.it> <usSlY-3wU-39@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Sat, 23 Sep 2017, Ingo Molnar wrote:
>  static inline int
>  __copy_xstate_to_kernel(void *kbuf,
>  			const void *data,
> -			unsigned int pos, unsigned int count, int end_pos)
> +			unsigned int offset, unsigned int size, int size_total)

Why is size_total int?

>  {
> -	if (!count)
> +	if (!size)
>  		return 0;
>  
> -	if (end_pos < 0 || pos < end_pos) {
> -		unsigned int copy = end_pos < 0 ? count : min(count, end_pos - pos);
> +	if (size_total < 0 || offset < size_total) {

And why would it be < 0? The call sites of this inline are all inside of:

int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave,
    			unsigned int offset_start, int size_total)

and hand in size_total completely unmodified. copy_xstate_to_kernel()
itself has a single callsite:

int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
                unsigned int pos, unsigned int count,
                void *kbuf, void __user *ubuf)

and that hands in count unmodified.

The same issue is with the to_user() variant which is even more
obvious. All callers are inside of copy_xstate_to_user() where size_total
is an unsigned int argument which is handed in unmodified.

This signed/unsigned mismatch is confusing at best.

Thanks,

	tglx

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Thread

[PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 19/33] x86/fpu: Decouple fpregs_activate()/fpregs_deactivate() from fpu->fpregs_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Decouple  fpregs_activate()/fpregs_deactivate() from fpu->fpregs_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 15/33] x86/fpu: Simplify fpu->fpregs_active use Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Simplify fpu->fpregs_active use tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 26/33] x86/fpu: Reinitialize FPU registers if restoring FPU state fails Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Reinitialize FPU registers if restoring FPU  state fails tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 32/33] x86/fpu: Rename fpu__activate_curr() to fpu__initialize() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename fpu__activate_curr() to  fpu__initialize() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 31/33] x86/fpu: Simplify and speed up fpu__copy() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Simplify and speed up fpu__copy() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 21/33] x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Add FPU state copying quirk to handle XRSTOR  failure on Intel Skylake CPUs tip-bot for Rik van Riel <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 13/33] x86/fpu: Remove 'kbuf' parameter from the copy_user_to_xstate() API Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'kbuf' parameter from the  copy_user_to_xstate() API tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 33/33] x86/fpu: Rename fpu__activate_fpstate_read/write() to fpu__read/write() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 02/33] x86/fpu: Split copy_xstate_to_user() into copy_xstate_to_kernel() & copy_xstate_to_user() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split copy_xstate_to_user() into  copy_xstate_to_kernel() & copy_xstate_to_user() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 16/33] x86/fpu: Make the fpu state change in fpu__clear() scheduler-atomic Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Make the fpu state change in fpu__clear()  scheduler-atomic tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 14/33] x86/fpu: Flip the parameter order in copy_*_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Flip the parameter order in  copy_*_to_xstate() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 11/33] x86/fpu: Split copy_user_to_xstate() into copy_kernel_to_xstate() & copy_user_to_xstate() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split copy_user_to_xstate() into  copy_kernel_to_xstate() & copy_user_to_xstate() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 07/33] x86/fpu: Remove the 'start_pos' parameter from the __copy_xstate_to_*() functions Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove the 'start_pos' parameter from the  __copy_xstate_to_*() functions tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 01/33] x86/fpu: Rename copyin_to_xsaves()/copyout_from_xsaves() to copy_user_to_xstate()/copy_xstate_to_user() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename  copyin_to_xsaves()/copyout_from_xsaves() to  copy_user_to_xstate()/copy_xstate_to_user() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 29/33] x86/fpu: Rename fpu::fpstate_active to fpu::initialized Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Rename fpu::fpstate_active to  fpu::initialized tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 17/33] x86/fpu: Split the state handling in fpu__drop() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Split the state handling in fpu__drop() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 09/33] x86/fpu: Change 'size_total' parameter to unsigned and standardize the size checks in copy_xstate_to_*() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Change 'size_total' parameter to unsigned  and standardize the size checks in copy_xstate_to_*() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 30/33] x86/fpu: Fix stale comments about lazy FPU logic Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix stale comments about lazy FPU logic tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 08/33] x86/fpu: Clarify parameter names in the copy_xstate_to_*() methods Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods Thomas Gleixner <tglx@linutronix.de> - 2017-09-25 22:00 +0200
      Re: [PATCH 08/33] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods Thomas Gleixner <tglx@linutronix.de> - 2017-09-25 22:10 +0200
    [tip:x86/fpu] x86/fpu: Clarify parameter names in the  copy_xstate_to_*() methods tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 20/33] x86/fpu: Remove struct fpu::fpregs_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove struct fpu::fpregs_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 03/33] x86/fpu: Remove 'ubuf' parameter from the copy_xstate_to_kernel() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'ubuf' parameter from the  copy_xstate_to_kernel() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:30 +0200
  [PATCH 23/33] x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Turn WARN_ON() in context switch into  WARN_ON_FPU() tip-bot for Andi Kleen <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 22/33] x86/fpu: Fix boolreturn.cocci warnings Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix boolreturn.cocci warnings tip-bot for kbuild test robot <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 06/33] x86/fpu: Clean up the parameter definitions of copy_xstate_to_*() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Clean up the parameter definitions of  copy_xstate_to_*() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 04/33] x86/fpu: Remove 'kbuf' parameter from the copy_xstate_to_user() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'kbuf' parameter from the  copy_xstate_to_user() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 05/33] x86/fpu: Clean up parameter order in the copy_xstate_to_*() APIs Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Clean up parameter order in the  copy_xstate_to_*() APIs tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 24/33] x86/fpu: Don't let userspace set bogus xcomp_bv Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Don't let userspace set bogus xcomp_bv tip-bot for Eric Biggers <tipbot@zytor.com> - 2017-09-26 10:50 +0200
  [PATCH 18/33] x86/fpu: Change fpu->fpregs_active users to fpu->fpstate_active Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Change fpu->fpregs_active users to  fpu->fpstate_active tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 27/33] x86/fpu: Simplify fpu__activate_fpstate_read() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Fix fpu__activate_fpstate_read() and update  comments tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 12/33] x86/fpu: Remove 'ubuf' parameter from the copy_kernel_to_xstate() API Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove 'ubuf' parameter from the  copy_kernel_to_xstate() API tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  [PATCH 25/33] x86/fpu: Tighten validation of user-supplied xstate_header Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
  [PATCH 28/33] x86/fpu: Remove fpu__current_fpstate_write_begin/end() Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    [tip:x86/fpu] x86/fpu: Remove  fpu__current_fpstate_write_begin/end() tip-bot for Ingo Molnar <tipbot@zytor.com> - 2017-09-26 10:40 +0200
  Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-23 15:10 +0200
    Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Juergen Gross <jgross@suse.com> - 2017-09-23 17:10 +0200
      Re: [PATCH 00/33] x86 FPU fixes and cleanups for v4.14 Ingo Molnar <mingo@kernel.org> - 2017-09-24 01:30 +0200

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