From: Mark Rutland <mark.rutland@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: keescook@chromium.org, maz@kernel.org, robin.murphy@arm.com,
broonie@kernel.org, james.morse@arm.com,
julien.thierry.kdev@gmail.com, catalin.marinas@arm.com,
labbott@redhat.com, will@kernel.org,
linux-arm-kernel@lists.infradead.org, alex.popov@linux.com
Subject: Re: [PATCH 05/17] arm64: entry: add a call_on_stack helper
Date: Tue, 14 Jan 2020 18:24:22 +0000 [thread overview]
Message-ID: <20200114182422.GA27165@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <98534fbd-5600-5ae2-a117-3bad76ddbe04@arm.com>
On Thu, Jan 09, 2020 at 01:30:02PM +0530, Anshuman Khandual wrote:
>
>
> On 01/09/2020 12:26 AM, Mark Rutland wrote:
> > In some cases, we want to call a function from C code, using an
> > alternative stack. Add a helper that we can use in such cases.
> >
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: James Morse <james.morse@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > ---
> > arch/arm64/include/asm/exception.h | 2 ++
> > arch/arm64/kernel/entry.S | 21 +++++++++++++++++++++
> > 2 files changed, 23 insertions(+)
> >
> > diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
> > index b87c6e276ab1..a49038fa4faf 100644
> > --- a/arch/arm64/include/asm/exception.h
> > +++ b/arch/arm64/include/asm/exception.h
> > @@ -31,6 +31,8 @@ static inline u32 disr_to_esr(u64 disr)
> > return esr;
> > }
> >
> > +asmlinkage void call_on_stack(struct pt_regs *, void (*)(struct pt_regs *),
> > + unsigned long);
> > asmlinkage void enter_from_user_mode(void);
> > void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs);
> > void do_sp_pc_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs);
> > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> > index 53ce1877a4aa..184313c773ea 100644
> > --- a/arch/arm64/kernel/entry.S
> > +++ b/arch/arm64/kernel/entry.S
> > @@ -901,6 +901,27 @@ ENTRY(ret_from_fork)
> > ENDPROC(ret_from_fork)
> > NOKPROBE(ret_from_fork)
> >
> > +/*
> > + * x0 = argument to function
>
> A small nit. Though the definition here itself does not limit the
> argument type, it might worth to mention that to be struct pt_regs
> per the previous declaration.
>
True.
To make this clearer, I've given the C prototype instead, as we do for the
SMCCC wrappers:
/*
* void call_on_stack(struct pt_regs *regs,
* void (*func)(struct pt_regs *),
* unsigned long new_sp)
*
* Calls func(regs) using new_sp as the initial stack pointer.
*/
> > +ENTRY(call_on_stack)
> > + /* Create a frame record to save our LR and SP (implicit in FP) */
> > + stp x29, x30, [sp, #-16]!
> > + mov x29, sp
> > +
> > + /* Move to the new stack and call the function there */
> > + mov sp, x2
> > + blr x1
> > +
> > + /* Restore SP from the FP, FP and LR from the record, and return */
> > + mov sp, x29
> > + ldp x29, x30, [sp], #16
> > + ret
> > +ENDPROC(call_on_stack)
> > +NOKPROBE(call_on_stack)
> > +
> > #ifdef CONFIG_ARM_SDE_INTERFACE
> >
> > #include <asm/sdei.h>
> >
>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Thanks!
Mark.
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next prev parent reply other threads:[~2020-01-14 18:24 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-08 18:56 [PATCH 00/17] arm64: entry deasmification and cleanup Mark Rutland
2020-01-08 18:56 ` [PATCH 01/17] arm64: entry: mark all entry code as notrace Mark Rutland
2020-01-09 5:21 ` Anshuman Khandual
2020-01-13 15:44 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 02/17] arm64: entry: cleanup el0 svc handler naming Mark Rutland
2020-01-09 5:33 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 03/17] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2020-01-09 5:36 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 04/17] arm64: entry: move preempt logic to C Mark Rutland
2020-01-09 6:43 ` Anshuman Khandual
2020-01-09 12:22 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 05/17] arm64: entry: add a call_on_stack helper Mark Rutland
2020-01-09 8:00 ` Anshuman Khandual
2020-01-14 18:24 ` Mark Rutland [this message]
2020-01-09 14:30 ` Laura Abbott
2020-01-09 14:46 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 06/17] arm64: entry: convert irq entry to C Mark Rutland
2020-01-08 18:56 ` [PATCH 07/17] arm64: entry: convert error " Mark Rutland
2020-01-09 9:12 ` Anshuman Khandual
2020-01-09 12:49 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 08/17] arm64: entry: Split el0_sync_compat from el0_sync Mark Rutland
2020-01-09 9:50 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 09/17] arm64: entry: organise handler stubs consistently Mark Rutland
2020-01-09 10:01 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 10/17] arm64: entry: consolidate EL1 return paths Mark Rutland
2020-01-10 3:39 ` Anshuman Khandual
2020-01-10 16:02 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 11/17] stackleak: allow C to call stackleak_erase() Mark Rutland
2020-01-10 3:45 ` Anshuman Khandual
2020-01-10 16:07 ` Mark Rutland
2020-01-27 23:00 ` Kees Cook
2020-01-08 18:56 ` [PATCH 12/17] arm64: debug-monitors: refactor MDSCR manipulation Mark Rutland
2020-01-10 4:35 ` Anshuman Khandual
2020-01-10 16:09 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 13/17] arm64: entry: move common el0 entry/return work to C Mark Rutland
2020-01-09 15:19 ` Mark Rutland
2020-01-08 18:56 ` [PATCH 14/17] arm64: entry: move NO_SYSCALL setup " Mark Rutland
2020-01-10 5:37 ` Anshuman Khandual
2020-01-08 18:56 ` [PATCH 15/17] arm64: entry: move ARM64_ERRATUM_845719 workaround " Mark Rutland
2020-01-08 18:56 ` [PATCH 16/17] arm64: entry: move ARM64_ERRATUM_1418040 " Mark Rutland
2020-01-08 18:56 ` [PATCH 17/17] arm64: entry: cleanup sp_el0 manipulation Mark Rutland
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