linux-kernel - Re: [PATCH 04/16] Add minimum address parameter to efi_low_alloc()

Open Source and information security mailing list archives

Date:	Fri, 30 Aug 2013 14:01:31 +0100
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Roy Franz <roy.franz@...aro.org>, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	matt.fleming@...el.com, linux@....linux.org.uk
Cc:	Roy Franz <roy.franz@...aro.org>, dave.martin@....com,
	leif.lindholm@...aro.org, msalter@...hat.com
Subject: Re: [PATCH 04/16] Add minimum address parameter to efi_low_alloc()

On Fri,  9 Aug 2013 16:26:05 -0700, Roy Franz <roy.franz@...aro.org> wrote:
> This allows allocations to be made low in memory while
> avoiding allocations at the base of memory.

Your commit message should include /why/ the change is needed. From the
above I understand what the patch does, but I don't understand why it is
necessary.

The patch looks fine to me, but it would be worth investigating merging
alloc_low and alloc_high. It looks like they both do pretty close to the
same calculations. A single core function could do both, could have both
minimum and maximum constraints, and could have a flag to determine if
low or high addresses should be preferred.

g.

Reviewed-by: Grant Likely <grant.likely@...aro.org>

> 
> Signed-off-by: Roy Franz <roy.franz@...aro.org>
> ---
>  arch/x86/boot/compressed/eboot.c       |   11 ++++++-----
>  drivers/firmware/efi/efi-stub-helper.c |    7 +++++--
>  2 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index 2a4430a..f44ef2f 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -458,7 +458,7 @@ struct boot_params *make_boot_params(void *handle, efi_system_table_t *_table)
>  	}
>  
>  	status = efi_low_alloc(sys_table, 0x4000, 1,
> -			       (unsigned long *)&boot_params);
> +			       (unsigned long *)&boot_params, 0);
>  	if (status != EFI_SUCCESS) {
>  		efi_printk(sys_table, "Failed to alloc lowmem for boot params\n");
>  		return NULL;
> @@ -505,7 +505,7 @@ struct boot_params *make_boot_params(void *handle, efi_system_table_t *_table)
>  			options_size++;	/* NUL termination */
>  
>  			status = efi_low_alloc(sys_table, options_size, 1,
> -					   &cmdline);
> +					   &cmdline, 0);
>  			if (status != EFI_SUCCESS) {
>  				efi_printk(sys_table, "Failed to alloc mem for cmdline\n");
>  				goto fail;
> @@ -563,7 +563,8 @@ static efi_status_t exit_boot(struct boot_params *boot_params,
>  again:
>  	size += sizeof(*mem_map) * 2;
>  	_size = size;
> -	status = efi_low_alloc(sys_table, size, 1, (unsigned long *)&mem_map);
> +	status = efi_low_alloc(sys_table, size, 1,
> +			       (unsigned long *)&mem_map, 0);
>  	if (status != EFI_SUCCESS)
>  		return status;
>  
> @@ -697,7 +698,7 @@ static efi_status_t relocate_kernel(struct setup_header *hdr)
>  				nr_pages, &start);
>  	if (status != EFI_SUCCESS) {
>  		status = efi_low_alloc(sys_table, hdr->init_size,
> -				   hdr->kernel_alignment, &start);
> +				   hdr->kernel_alignment, &start, 0);
>  		if (status != EFI_SUCCESS)
>  			efi_printk(sys_table, "Failed to alloc mem for kernel\n");
>  	}
> @@ -745,7 +746,7 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
>  
>  	gdt->size = 0x800;
>  	status = efi_low_alloc(sys_table, gdt->size, 8,
> -			   (unsigned long *)&gdt->address);
> +			   (unsigned long *)&gdt->address, 0);
>  	if (status != EFI_SUCCESS) {
>  		efi_printk(sys_table, "Failed to alloc mem for gdt\n");
>  		goto fail;
> diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/efi-stub-helper.c
> index 0218d535..40cd16e 100644
> --- a/drivers/firmware/efi/efi-stub-helper.c
> +++ b/drivers/firmware/efi/efi-stub-helper.c
> @@ -163,11 +163,11 @@ fail:
>  }
>  
>  /*
> - * Allocate at the lowest possible address.
> + * Allocate at the lowest possible address, that is not below min.
>   */
>  static efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
>  			      unsigned long size, unsigned long align,
> -			      unsigned long *addr)
> +			      unsigned long *addr, unsigned long min)
>  {
>  	unsigned long map_size, desc_size;
>  	efi_memory_desc_t *map;
> @@ -204,6 +204,9 @@ static efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
>  		if (start == 0x0)
>  			start += 8;
>  
> +		if (start < min)
> +			start = min;
> +
>  		start = round_up(start, align);
>  		if ((start + size) > end)
>  			continue;
> -- 
> 1.7.10.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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