Re: [PATCH 22/38] MIPS: VDSO: Drop gic_get_usm_range() usage

[Marc Zyngier <marc.zyngier@arm.com>]

On 18/08/17 17:47, Paul Burton wrote:
> Hi Marc,
> 
> On Friday, 18 August 2017 04:38:50 PDT Marc Zyngier wrote:
>> On 13/08/17 05:36, Paul Burton wrote:
>>> We don't really need gic_get_usm_range() to abstract discovery of the
>>> address of the GIC user-visible section now that we have access to its
>>> base address globally.
>>>
>>> Switch to calculating it ourselves, which will allow us to stop
>>> requiring the irqchip driver to care about a counter exposed to userland
>>> for use via the VDSO.
>>>
>>> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
>>> Cc: Jason Cooper <jason@lakedaemon.net>
>>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>>> Cc: Ralf Baechle <ralf@linux-mips.org>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: linux-mips@linux-mips.org
>>> ---
>>>
>>>  arch/mips/kernel/vdso.c | 15 +++++----------
>>>  1 file changed, 5 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
>>> index 093517e85a6c..019035d7225c 100644
>>> --- a/arch/mips/kernel/vdso.c
>>> +++ b/arch/mips/kernel/vdso.c
>>> @@ -13,13 +13,13 @@
>>>
>>>  #include <linux/err.h>
>>>  #include <linux/init.h>
>>>  #include <linux/ioport.h>
>>>
>>> -#include <linux/irqchip/mips-gic.h>
>>>
>>>  #include <linux/mm.h>
>>>  #include <linux/sched.h>
>>>  #include <linux/slab.h>
>>>  #include <linux/timekeeper_internal.h>
>>>  
>>>  #include <asm/abi.h>
>>>
>>> +#include <asm/mips-cps.h>
>>>
>>>  #include <asm/vdso.h>
>>>  
>>>  /* Kernel-provided data used by the VDSO. */
>>>
>>> @@ -99,9 +99,8 @@ int arch_setup_additional_pages(struct linux_binprm
>>> *bprm, int uses_interp)> 
>>>  {
>>>  
>>>  	struct mips_vdso_image *image = current->thread.abi->vdso;
>>>  	struct mm_struct *mm = current->mm;
>>>
>>> -	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr;
>>> +	unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr,
>>> gic_pfn;> 
>>>  	struct vm_area_struct *vma;
>>>
>>> -	struct resource gic_res;
>>>
>>>  	int ret;
>>>  	
>>>  	if (down_write_killable(&mm->mmap_sem))
>>>
>>> @@ -125,7 +124,7 @@ int arch_setup_additional_pages(struct linux_binprm
>>> *bprm, int uses_interp)> 
>>>  	 * only map a page even though the total area is 64K, as we only need
>>>  	 * the counter registers at the start.
>>>  	 */
>>>
>>> -	gic_size = gic_present ? PAGE_SIZE : 0;
>>> +	gic_size = mips_gic_present() ? PAGE_SIZE : 0;
>>>
>>>  	vvar_size = gic_size + PAGE_SIZE;
>>>  	size = vvar_size + image->size;
>>>
>>> @@ -148,13 +147,9 @@ int arch_setup_additional_pages(struct linux_binprm
>>> *bprm, int uses_interp)> 
>>>  	/* Map GIC user page. */
>>>  	if (gic_size) {
>>>
>>> -		ret = gic_get_usm_range(&gic_res);
>>> -		if (ret)
>>> -			goto out;
>>> +		gic_pfn = virt_to_phys(mips_gic_base + MIPS_GIC_USER_OFS) >>
>>> PAGE_SHIFT;
>>
>> virt_to_pfn() instead?
> 
> We don't seem to have virt_to_pfn() on MIPS, but I'd be happy to add it & tidy 
> up a few places that could use it. Would you mind if that cleanup came 
> separately though?

I don't mind either way. This is a fairly common shortcut, but no need
to introduce it (and add more dependencies) on this account.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...