[PATCH] arm64/efi: prefer AllocatePages() over efi_low_alloc() for vmlinux

[PATCH] arm64/efi: prefer AllocatePages() over efi_low_alloc() for vmlinux

[Ard Biesheuvel]

When allocating memory for the kernel image, try the AllocatePages()
boot service to obtain memory at the preferred offset of
'dram_base + TEXT_OFFSET', and only revert to efi_low_alloc() if that
fails. This is the only way to allocate at the base of DRAM if DRAM
starts at 0x0, since efi_low_alloc() refuses to allocate at 0x0.

Tested-by: Haojian Zhuang <haojian.zhuang-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 arch/arm64/kernel/efi-stub.c | 47 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
index f5374065ad53..c8df74d14368 100644
--- a/arch/arm64/kernel/efi-stub.c
+++ b/arch/arm64/kernel/efi-stub.c
@@ -13,7 +13,7 @@
 #include <asm/efi.h>
 #include <asm/sections.h>
 
-efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
+efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 					unsigned long *image_addr,
 					unsigned long *image_size,
 					unsigned long *reserve_addr,
@@ -23,21 +23,52 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
 {
 	efi_status_t status;
 	unsigned long kernel_size, kernel_memsize = 0;
+	unsigned long nr_pages;
 
 	/* Relocate the image, if required. */
 	kernel_size = _edata - _text;
 	if (*image_addr != (dram_base + TEXT_OFFSET)) {
 		kernel_memsize = kernel_size + (_end - _edata);
-		status = efi_low_alloc(sys_table, kernel_memsize + TEXT_OFFSET,
-				       SZ_2M, reserve_addr);
+
+		//
+		// First, try a straight allocation at the preferred offset.
+		// This will work around the issue where, if dram_base == 0x0,
+		// efi_low_alloc() refuses to allocate at 0x0 (to prevent the
+		// address of the allocation to be mistaken for a FAIL return
+		// value or a NULL pointer). It will also ensure that, on
+		// platforms where the [dram_base, dram_base + TEXT_OFFSET)
+		// interval is partially occupied by the firmware (like on APM
+		// Mustang), we can still place the kernel at the address
+		// 'dram_base + TEXT_OFFSET'.
+		//
+		*reserve_addr = dram_base + TEXT_OFFSET;
+		nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
+			   EFI_PAGE_SIZE;
+		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
+					EFI_LOADER_DATA, nr_pages,
+					(efi_physical_addr_t *)reserve_addr);
+		if (status == EFI_SUCCESS) {
+			memcpy((void *)*reserve_addr, (void *)*image_addr,
+			       kernel_size);
+			*image_addr = *reserve_addr;
+			*reserve_size = kernel_memsize;
+		} else {
+			status = efi_low_alloc(sys_table_arg,
+					       kernel_memsize + TEXT_OFFSET,
+					       SZ_2M, reserve_addr);
+
+			if (status == EFI_SUCCESS) {
+				memcpy((void *)*reserve_addr + TEXT_OFFSET,
+				       (void *)*image_addr,
+				       kernel_size);
+				*image_addr = *reserve_addr + TEXT_OFFSET;
+				*reserve_size = kernel_memsize + TEXT_OFFSET;
+			}
+		}
 		if (status != EFI_SUCCESS) {
-			pr_efi_err(sys_table, "Failed to relocate kernel\n");
+			pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
 			return status;
 		}
-		memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
-		       kernel_size);
-		*image_addr = *reserve_addr + TEXT_OFFSET;
-		*reserve_size = kernel_memsize + TEXT_OFFSET;
 	}
 
 
-- 
1.9.1

Re: [PATCH] arm64/efi: prefer AllocatePages() over efi_low_alloc() for vmlinux

[Mark Rutland]

Hi Ard,

On Fri, Jul 24, 2015 at 10:41:53AM +0100, Ard Biesheuvel wrote:
> When allocating memory for the kernel image, try the AllocatePages()
> boot service to obtain memory at the preferred offset of
> 'dram_base + TEXT_OFFSET', and only revert to efi_low_alloc() if that
> fails. This is the only way to allocate at the base of DRAM if DRAM
> starts at 0x0, since efi_low_alloc() refuses to allocate at 0x0.
>
> Tested-by: Haojian Zhuang <haojian.zhuang-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  arch/arm64/kernel/efi-stub.c | 47 ++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 39 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> index f5374065ad53..c8df74d14368 100644
> --- a/arch/arm64/kernel/efi-stub.c
> +++ b/arch/arm64/kernel/efi-stub.c
> @@ -13,7 +13,7 @@
>  #include <asm/efi.h>
>  #include <asm/sections.h>
>  
> -efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
> +efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,

Any reason for the _arg addition?

>  					unsigned long *image_addr,
>  					unsigned long *image_size,
>  					unsigned long *reserve_addr,
> @@ -23,21 +23,52 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
>  {
>  	efi_status_t status;
>  	unsigned long kernel_size, kernel_memsize = 0;
> +	unsigned long nr_pages;
>  
>  	/* Relocate the image, if required. */
>  	kernel_size = _edata - _text;
>  	if (*image_addr != (dram_base + TEXT_OFFSET)) {
>  		kernel_memsize = kernel_size + (_end - _edata);
> -		status = efi_low_alloc(sys_table, kernel_memsize + TEXT_OFFSET,
> -				       SZ_2M, reserve_addr);
> +
> +		//
> +		// First, try a straight allocation at the preferred offset.
> +		// This will work around the issue where, if dram_base == 0x0,
> +		// efi_low_alloc() refuses to allocate at 0x0 (to prevent the
> +		// address of the allocation to be mistaken for a FAIL return
> +		// value or a NULL pointer). It will also ensure that, on
> +		// platforms where the [dram_base, dram_base + TEXT_OFFSET)
> +		// interval is partially occupied by the firmware (like on APM
> +		// Mustang), we can still place the kernel at the address
> +		// 'dram_base + TEXT_OFFSET'.
> +		//

/*
 * Nit: please use the standard comment style
 */

> +		*reserve_addr = dram_base + TEXT_OFFSET;
> +		nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
> +			   EFI_PAGE_SIZE;
> +		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
> +					EFI_LOADER_DATA, nr_pages,
> +					(efi_physical_addr_t *)reserve_addr);
> +		if (status == EFI_SUCCESS) {
> +			memcpy((void *)*reserve_addr, (void *)*image_addr,
> +			       kernel_size);
> +			*image_addr = *reserve_addr;
> +			*reserve_size = kernel_memsize;
> +		} else {
> +			status = efi_low_alloc(sys_table_arg,
> +					       kernel_memsize + TEXT_OFFSET,
> +					       SZ_2M, reserve_addr);
> +
> +			if (status == EFI_SUCCESS) {
> +				memcpy((void *)*reserve_addr + TEXT_OFFSET,
> +				       (void *)*image_addr,
> +				       kernel_size);
> +				*image_addr = *reserve_addr + TEXT_OFFSET;
> +				*reserve_size = kernel_memsize + TEXT_OFFSET;
> +			}
> +		}
>  		if (status != EFI_SUCCESS) {
> -			pr_efi_err(sys_table, "Failed to relocate kernel\n");
> +			pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
>  			return status;
>  		}
> -		memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
> -		       kernel_size);

Could we have a new_image_addr assigned in each case, and keep the
common memcpy here, followed by assignment to *image_addr? That would
save a couple of lines and guarantee the two cases stay in sync.

Otherwise this looks good to me.

Thanks,
Mark.

Re: [PATCH] arm64/efi: prefer AllocatePages() over efi_low_alloc() for vmlinux

[Ard Biesheuvel]

On 24 July 2015 at 12:49, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> wrote:
> Hi Ard,
>
> On Fri, Jul 24, 2015 at 10:41:53AM +0100, Ard Biesheuvel wrote:
>> When allocating memory for the kernel image, try the AllocatePages()
>> boot service to obtain memory at the preferred offset of
>> 'dram_base + TEXT_OFFSET', and only revert to efi_low_alloc() if that
>> fails. This is the only way to allocate at the base of DRAM if DRAM
>> starts at 0x0, since efi_low_alloc() refuses to allocate at 0x0.
>>
>> Tested-by: Haojian Zhuang <haojian.zhuang-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>> ---
>>  arch/arm64/kernel/efi-stub.c | 47 ++++++++++++++++++++++++++++++++++++--------
>>  1 file changed, 39 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
>> index f5374065ad53..c8df74d14368 100644
>> --- a/arch/arm64/kernel/efi-stub.c
>> +++ b/arch/arm64/kernel/efi-stub.c
>> @@ -13,7 +13,7 @@
>>  #include <asm/efi.h>
>>  #include <asm/sections.h>
>>
>> -efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
>> +efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
>
> Any reason for the _arg addition?
>

Yes. Unfortunately, the efi_call_early() macro has a hidden
'efi_system_table_t *' parameter which it refers to by the name
'sys_table_arg'

>>                                       unsigned long *image_addr,
>>                                       unsigned long *image_size,
>>                                       unsigned long *reserve_addr,
>> @@ -23,21 +23,52 @@ efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
>>  {
>>       efi_status_t status;
>>       unsigned long kernel_size, kernel_memsize = 0;
>> +     unsigned long nr_pages;
>>
>>       /* Relocate the image, if required. */
>>       kernel_size = _edata - _text;
>>       if (*image_addr != (dram_base + TEXT_OFFSET)) {
>>               kernel_memsize = kernel_size + (_end - _edata);
>> -             status = efi_low_alloc(sys_table, kernel_memsize + TEXT_OFFSET,
>> -                                    SZ_2M, reserve_addr);
>> +
>> +             //
>> +             // First, try a straight allocation at the preferred offset.
>> +             // This will work around the issue where, if dram_base == 0x0,
>> +             // efi_low_alloc() refuses to allocate at 0x0 (to prevent the
>> +             // address of the allocation to be mistaken for a FAIL return
>> +             // value or a NULL pointer). It will also ensure that, on
>> +             // platforms where the [dram_base, dram_base + TEXT_OFFSET)
>> +             // interval is partially occupied by the firmware (like on APM
>> +             // Mustang), we can still place the kernel at the address
>> +             // 'dram_base + TEXT_OFFSET'.
>> +             //
>
> /*
>  * Nit: please use the standard comment style
>  */
>

Absolutely. EDK2 development must be really screwing with my brain if
I am unconsciously using C++ style comments in C code. Time to move
back to the light side for a while :-)

>> +             *reserve_addr = dram_base + TEXT_OFFSET;
>> +             nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
>> +                        EFI_PAGE_SIZE;
>> +             status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
>> +                                     EFI_LOADER_DATA, nr_pages,
>> +                                     (efi_physical_addr_t *)reserve_addr);
>> +             if (status == EFI_SUCCESS) {
>> +                     memcpy((void *)*reserve_addr, (void *)*image_addr,
>> +                            kernel_size);
>> +                     *image_addr = *reserve_addr;
>> +                     *reserve_size = kernel_memsize;
>> +             } else {
>> +                     status = efi_low_alloc(sys_table_arg,
>> +                                            kernel_memsize + TEXT_OFFSET,
>> +                                            SZ_2M, reserve_addr);
>> +
>> +                     if (status == EFI_SUCCESS) {
>> +                             memcpy((void *)*reserve_addr + TEXT_OFFSET,
>> +                                    (void *)*image_addr,
>> +                                    kernel_size);
>> +                             *image_addr = *reserve_addr + TEXT_OFFSET;
>> +                             *reserve_size = kernel_memsize + TEXT_OFFSET;
>> +                     }
>> +             }
>>               if (status != EFI_SUCCESS) {
>> -                     pr_efi_err(sys_table, "Failed to relocate kernel\n");
>> +                     pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
>>                       return status;
>>               }
>> -             memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
>> -                    kernel_size);
>
> Could we have a new_image_addr assigned in each case, and keep the
> common memcpy here, followed by assignment to *image_addr? That would
> save a couple of lines and guarantee the two cases stay in sync.
>

Well, the memcpy() occurs before the assignment of *image_addr, which
is also used as the src arg. So I could record the value of
*image_addr in a temp, I suppose. I will do that in the next version.

> Otherwise this looks good to me.
>

Thanks,
Ard.

Re: [PATCH] arm64/efi: prefer AllocatePages() over efi_low_alloc() for vmlinux

[Mark Rutland]

On Fri, Jul 24, 2015 at 11:54:47AM +0100, Ard Biesheuvel wrote:
> On 24 July 2015 at 12:49, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> wrote:
> > Hi Ard,
> >
> > On Fri, Jul 24, 2015 at 10:41:53AM +0100, Ard Biesheuvel wrote:
> >> When allocating memory for the kernel image, try the AllocatePages()
> >> boot service to obtain memory at the preferred offset of
> >> 'dram_base + TEXT_OFFSET', and only revert to efi_low_alloc() if that
> >> fails. This is the only way to allocate at the base of DRAM if DRAM
> >> starts at 0x0, since efi_low_alloc() refuses to allocate at 0x0.
> >>
> >> Tested-by: Haojian Zhuang <haojian.zhuang-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> >> ---
> >>  arch/arm64/kernel/efi-stub.c | 47 ++++++++++++++++++++++++++++++++++++--------
> >>  1 file changed, 39 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/arch/arm64/kernel/efi-stub.c b/arch/arm64/kernel/efi-stub.c
> >> index f5374065ad53..c8df74d14368 100644
> >> --- a/arch/arm64/kernel/efi-stub.c
> >> +++ b/arch/arm64/kernel/efi-stub.c
> >> @@ -13,7 +13,7 @@
> >>  #include <asm/efi.h>
> >>  #include <asm/sections.h>
> >>
> >> -efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table,
> >> +efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
> >
> > Any reason for the _arg addition?
> >
> 
> Yes. Unfortunately, the efi_call_early() macro has a hidden
> 'efi_system_table_t *' parameter which it refers to by the name
> 'sys_table_arg'

Eww...

Ok, no worry.

> >> +             *reserve_addr = dram_base + TEXT_OFFSET;
> >> +             nr_pages = round_up(kernel_memsize, EFI_ALLOC_ALIGN) /
> >> +                        EFI_PAGE_SIZE;
> >> +             status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
> >> +                                     EFI_LOADER_DATA, nr_pages,
> >> +                                     (efi_physical_addr_t *)reserve_addr);
> >> +             if (status == EFI_SUCCESS) {
> >> +                     memcpy((void *)*reserve_addr, (void *)*image_addr,
> >> +                            kernel_size);
> >> +                     *image_addr = *reserve_addr;
> >> +                     *reserve_size = kernel_memsize;
> >> +             } else {
> >> +                     status = efi_low_alloc(sys_table_arg,
> >> +                                            kernel_memsize + TEXT_OFFSET,
> >> +                                            SZ_2M, reserve_addr);
> >> +
> >> +                     if (status == EFI_SUCCESS) {
> >> +                             memcpy((void *)*reserve_addr + TEXT_OFFSET,
> >> +                                    (void *)*image_addr,
> >> +                                    kernel_size);
> >> +                             *image_addr = *reserve_addr + TEXT_OFFSET;
> >> +                             *reserve_size = kernel_memsize + TEXT_OFFSET;
> >> +                     }
> >> +             }
> >>               if (status != EFI_SUCCESS) {
> >> -                     pr_efi_err(sys_table, "Failed to relocate kernel\n");
> >> +                     pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
> >>                       return status;
> >>               }
> >> -             memcpy((void *)*reserve_addr + TEXT_OFFSET, (void *)*image_addr,
> >> -                    kernel_size);
> >
> > Could we have a new_image_addr assigned in each case, and keep the
> > common memcpy here, followed by assignment to *image_addr? That would
> > save a couple of lines and guarantee the two cases stay in sync.
> >
> 
> Well, the memcpy() occurs before the assignment of *image_addr, which
> is also used as the src arg. So I could record the value of
> *image_addr in a temp, I suppose. I will do that in the next version.

Yup, I suggested the name new_image_addr for said temporary ;)

Thanks,
Mark.