linux-kernel - Re: [PATCH v10 4/8] powerpc: Use ima kexec node functions

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Date:   Sat, 05 Dec 2020 16:51:30 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
Cc:     zohar@...ux.ibm.com, robh@...nel.org, gregkh@...uxfoundation.org,
        james.morse@....com, catalin.marinas@....com, sashal@...nel.org,
        will@...nel.org, mpe@...erman.id.au, benh@...nel.crashing.org,
        paulus@...ba.org, robh+dt@...nel.org, frowand.list@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        dmitry.kasatkin@...il.com, jmorris@...ei.org, serge@...lyn.com,
        pasha.tatashin@...een.com, allison@...utok.net,
        kstewart@...uxfoundation.org, takahiro.akashi@...aro.org,
        tglx@...utronix.de, masahiroy@...nel.org, bhsharma@...hat.com,
        mbrugger@...e.com, hsinyi@...omium.org, tao.li@...o.com,
        christophe.leroy@....fr, linux-integrity@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        prsriva@...ux.microsoft.com, balajib@...ux.microsoft.com
Subject: Re: [PATCH v10 4/8] powerpc: Use ima kexec node functions


Lakshmi Ramasubramanian <nramas@...ux.microsoft.com> writes:

> do_get_kexec_buffer() and get_addr_size_cells() are called by
> ima_get_kexec_buffer(), ima_free_kexec_buffer, and remove_ima_buffer()
> to retrieve the address and size of the buffer used for carrying
> forward the IMA measurement log across kexec system call. These
> functions correctly handle a device tree property that is a child node
> of the root node, but not anything other than the immediate root
> child nodes.
>
> Use the architecture independent functions get_ima_kexec_buffer()
> and get_root_addr_size_cells() defined in "drivers/of/ima_kexec.c",

s/ima_kexec.c/kexec.c/

> to get the address and size of the IMA measurement log buffer from
> the device tree. Remove do_get_kexec_buffer() and get_addr_size_cells()
> since they are not used anymore.
>
> Co-developed-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
> Signed-off-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>

Looks good. Thanks!

Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>

> ---
>  arch/powerpc/kexec/ima.c | 58 +++++-----------------------------------
>  1 file changed, 7 insertions(+), 51 deletions(-)
>
> diff --git a/arch/powerpc/kexec/ima.c b/arch/powerpc/kexec/ima.c
> index a36c39db4b1a..906e8212435d 100644
> --- a/arch/powerpc/kexec/ima.c
> +++ b/arch/powerpc/kexec/ima.c
> @@ -13,40 +13,6 @@
>  #include <linux/libfdt.h>
>  #include <asm/ima.h>
>  
> -static int get_addr_size_cells(int *addr_cells, int *size_cells)
> -{
> -	struct device_node *root;
> -
> -	root = of_find_node_by_path("/");
> -	if (!root)
> -		return -EINVAL;
> -
> -	*addr_cells = of_n_addr_cells(root);
> -	*size_cells = of_n_size_cells(root);
> -
> -	of_node_put(root);
> -
> -	return 0;
> -}
> -
> -static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
> -			       size_t *size)
> -{
> -	int ret, addr_cells, size_cells;
> -
> -	ret = get_addr_size_cells(&addr_cells, &size_cells);
> -	if (ret)
> -		return ret;
> -
> -	if (len < 4 * (addr_cells + size_cells))
> -		return -ENOENT;
> -
> -	*addr = of_read_number(prop, addr_cells);
> -	*size = of_read_number(prop + 4 * addr_cells, size_cells);
> -
> -	return 0;
> -}
> -
>  /**
>   * ima_get_kexec_buffer - get IMA buffer from the previous kernel
>   * @addr:	On successful return, set to point to the buffer contents.
> @@ -56,16 +22,11 @@ static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
>   */
>  int ima_get_kexec_buffer(void **addr, size_t *size)
>  {
> -	int ret, len;
> +	int ret;
>  	unsigned long tmp_addr;
>  	size_t tmp_size;
> -	const void *prop;
>  
> -	prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len);
> -	if (!prop)
> -		return -ENOENT;
> -
> -	ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size);
> +	ret = get_ima_kexec_buffer(NULL, 0, &tmp_addr, &tmp_size);
>  	if (ret)
>  		return ret;
>  
> @@ -89,7 +50,7 @@ int ima_free_kexec_buffer(void)
>  	if (!prop)
>  		return -ENOENT;
>  
> -	ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size);
> +	ret = get_ima_kexec_buffer(NULL, 0, &addr, &size);
>  	if (ret)
>  		return ret;
>  
> @@ -98,7 +59,6 @@ int ima_free_kexec_buffer(void)
>  		return ret;
>  
>  	return memblock_free(addr, size);
> -
>  }
>  
>  /**
> @@ -112,19 +72,15 @@ int ima_free_kexec_buffer(void)
>   */
>  void remove_ima_buffer(void *fdt, int chosen_node)
>  {
> -	int ret, len;
> +	int ret;
>  	unsigned long addr;
>  	size_t size;
> -	const void *prop;
>  
> -	prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len);
> -	if (!prop)
> +	ret = get_ima_kexec_buffer(fdt, chosen_node, &addr, &size);
> +	if (ret)
>  		return;
>  
> -	ret = do_get_kexec_buffer(prop, len, &addr, &size);
>  	fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer");
> -	if (ret)
> -		return;
>  
>  	ret = delete_fdt_mem_rsv(fdt, addr, size);
>  	if (!ret)
> @@ -191,7 +147,7 @@ int setup_ima_buffer(const struct kimage *image, void *fdt, int chosen_node)
>  	if (!image->arch.ima_buffer_size)
>  		return 0;
>  
> -	ret = get_addr_size_cells(&addr_cells, &size_cells);
> +	ret = get_root_addr_size_cells(&addr_cells, &size_cells);
>  	if (ret)
>  		return ret;


-- 
Thiago Jung Bauermann
IBM Linux Technology Center