Re: [PATCH 3/8] powerpc: Mark functions called inside uaccess blocks w/ 'notrace'

From: "Christopher M. Riedl" <cmr@codefail.de>
To: "Christophe Leroy" <christophe.leroy@csgroup.eu>,
	<linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 3/8] powerpc: Mark functions called inside uaccess blocks w/ 'notrace'
Date: Mon, 19 Oct 2020 20:59:52 -0500	[thread overview]
Message-ID: <C6HCI5ZCNOK7.38L522D7VL2QR@geist> (raw)
In-Reply-To: <30d9ccba-20a5-37b4-1629-d0f9e0da4c84@csgroup.eu>

On Fri Oct 16, 2020 at 4:02 AM CDT, Christophe Leroy wrote:
>
>
> Le 15/10/2020 à 17:01, Christopher M. Riedl a écrit :
> > Functions called between user_*_access_begin() and user_*_access_end()
> > should be either inlined or marked 'notrace' to prevent leaving
> > userspace access exposed. Mark any such functions relevant to signal
> > handling so that subsequent patches can call them inside uaccess blocks.
>
> Is it enough to mark it "notrace" ? I see that when I activate KASAN,
> there are still KASAN calls in
> those functions.
>

Maybe not enough after all :(

> In my series for 32 bits, I re-ordered stuff in order to do all those
> calls before doing the
> _access_begin(), can't you do the same on PPC64 ? (See
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/f6eac65781b4a57220477c8864bca2b57f29a5d5.1597770847.git.christophe.leroy@csgroup.eu/)
>

Yes, I will give this another shot in the next spin.

> Christophe
>
> > 
> > Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
> > ---
> >   arch/powerpc/kernel/process.c | 20 ++++++++++----------
> >   arch/powerpc/mm/mem.c         |  4 ++--
> >   2 files changed, 12 insertions(+), 12 deletions(-)
> > 
> > diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> > index ba2c987b8403..bf5d9654bd2c 100644
> > --- a/arch/powerpc/kernel/process.c
> > +++ b/arch/powerpc/kernel/process.c
> > @@ -84,7 +84,7 @@ extern unsigned long _get_SP(void);
> >    */
> >   bool tm_suspend_disabled __ro_after_init = false;
> >   
> > -static void check_if_tm_restore_required(struct task_struct *tsk)
> > +static void notrace check_if_tm_restore_required(struct task_struct *tsk)
> >   {
> >   	/*
> >   	 * If we are saving the current thread's registers, and the
> > @@ -151,7 +151,7 @@ void notrace __msr_check_and_clear(unsigned long bits)
> >   EXPORT_SYMBOL(__msr_check_and_clear);
> >   
> >   #ifdef CONFIG_PPC_FPU
> > -static void __giveup_fpu(struct task_struct *tsk)
> > +static void notrace __giveup_fpu(struct task_struct *tsk)
> >   {
> >   	unsigned long msr;
> >   
> > @@ -163,7 +163,7 @@ static void __giveup_fpu(struct task_struct *tsk)
> >   	tsk->thread.regs->msr = msr;
> >   }
> >   
> > -void giveup_fpu(struct task_struct *tsk)
> > +void notrace giveup_fpu(struct task_struct *tsk)
> >   {
> >   	check_if_tm_restore_required(tsk);
> >   
> > @@ -177,7 +177,7 @@ EXPORT_SYMBOL(giveup_fpu);
> >    * Make sure the floating-point register state in the
> >    * the thread_struct is up to date for task tsk.
> >    */
> > -void flush_fp_to_thread(struct task_struct *tsk)
> > +void notrace flush_fp_to_thread(struct task_struct *tsk)
> >   {
> >   	if (tsk->thread.regs) {
> >   		/*
> > @@ -234,7 +234,7 @@ static inline void __giveup_fpu(struct task_struct *tsk) { }
> >   #endif /* CONFIG_PPC_FPU */
> >   
> >   #ifdef CONFIG_ALTIVEC
> > -static void __giveup_altivec(struct task_struct *tsk)
> > +static void notrace __giveup_altivec(struct task_struct *tsk)
> >   {
> >   	unsigned long msr;
> >   
> > @@ -246,7 +246,7 @@ static void __giveup_altivec(struct task_struct *tsk)
> >   	tsk->thread.regs->msr = msr;
> >   }
> >   
> > -void giveup_altivec(struct task_struct *tsk)
> > +void notrace giveup_altivec(struct task_struct *tsk)
> >   {
> >   	check_if_tm_restore_required(tsk);
> >   
> > @@ -285,7 +285,7 @@ EXPORT_SYMBOL(enable_kernel_altivec);
> >    * Make sure the VMX/Altivec register state in the
> >    * the thread_struct is up to date for task tsk.
> >    */
> > -void flush_altivec_to_thread(struct task_struct *tsk)
> > +void notrace flush_altivec_to_thread(struct task_struct *tsk)
> >   {
> >   	if (tsk->thread.regs) {
> >   		preempt_disable();
> > @@ -300,7 +300,7 @@ EXPORT_SYMBOL_GPL(flush_altivec_to_thread);
> >   #endif /* CONFIG_ALTIVEC */
> >   
> >   #ifdef CONFIG_VSX
> > -static void __giveup_vsx(struct task_struct *tsk)
> > +static void notrace __giveup_vsx(struct task_struct *tsk)
> >   {
> >   	unsigned long msr = tsk->thread.regs->msr;
> >   
> > @@ -317,7 +317,7 @@ static void __giveup_vsx(struct task_struct *tsk)
> >   		__giveup_altivec(tsk);
> >   }
> >   
> > -static void giveup_vsx(struct task_struct *tsk)
> > +static void notrace giveup_vsx(struct task_struct *tsk)
> >   {
> >   	check_if_tm_restore_required(tsk);
> >   
> > @@ -352,7 +352,7 @@ void enable_kernel_vsx(void)
> >   }
> >   EXPORT_SYMBOL(enable_kernel_vsx);
> >   
> > -void flush_vsx_to_thread(struct task_struct *tsk)
> > +void notrace flush_vsx_to_thread(struct task_struct *tsk)
> >   {
> >   	if (tsk->thread.regs) {
> >   		preempt_disable();
> > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> > index ddc32cc1b6cf..da2345a2abc6 100644
> > --- a/arch/powerpc/mm/mem.c
> > +++ b/arch/powerpc/mm/mem.c
> > @@ -378,7 +378,7 @@ static inline bool flush_coherent_icache(unsigned long addr)
> >    * @start: the start address
> >    * @stop: the stop address (exclusive)
> >    */
> > -static void invalidate_icache_range(unsigned long start, unsigned long stop)
> > +static void notrace invalidate_icache_range(unsigned long start, unsigned long stop)
> >   {
> >   	unsigned long shift = l1_icache_shift();
> >   	unsigned long bytes = l1_icache_bytes();
> > @@ -402,7 +402,7 @@ static void invalidate_icache_range(unsigned long start, unsigned long stop)
> >    * @start: the start address
> >    * @stop: the stop address (exclusive)
> >    */
> > -void flush_icache_range(unsigned long start, unsigned long stop)
> > +void notrace flush_icache_range(unsigned long start, unsigned long stop)
> >   {
> >   	if (flush_coherent_icache(start))
> >   		return;
> > 