Message-ID: <4a8a9d8f-22b8-0961-7c31-39eb1fe9cb65@linux.microsoft.com>
Date:   Fri, 11 Dec 2020 08:37:21 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Thiago Jung Bauermann <bauerman@...ux.ibm.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 2/8] powerpc: Move delete_fdt_mem_rsv() to
 drivers/of/kexec.c

On 12/6/20 5:50 PM, Lakshmi Ramasubramanian wrote:

Hi Thiago,

> On 12/4/20 6:22 PM, Thiago Jung Bauermann wrote
>>
>> Hello Lakshmi,
>>
>> Lakshmi Ramasubramanian <nramas@...ux.microsoft.com> writes:
>>
>>> delete_fdt_mem_rsv() retrieves the memory reserve map entry, for
>>> the given starting address and size, from the device tree blob, and
>>> removes the entry from the device tree blob. This function is called
>>> to free the resources reserved for the buffer used for carrying forward
>>> the IMA measurement logs on kexec. This function does not have
>>> architecture specific code, but is currently limited to powerpc.
>>>
>>> Move delete_fdt_mem_rsv() to "drivers/of/kexec_fdt.c" so that it is
>>
>> s/kexec_fdt.c/kexec.c/
> 
> Missed that in the patch description. Will fix it. Thanks.
> 
>>> accessible for other architectures as well.
>>>
>>> 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>
>>> ---
>>>   arch/powerpc/include/asm/kexec.h |  1 -
>>>   arch/powerpc/kexec/file_load.c   | 32 -----------------
>>>   drivers/of/Makefile              |  1 +
>>>   drivers/of/kexec.c               | 61 ++++++++++++++++++++++++++++++++
>>>   include/linux/kexec.h            |  5 +++
>>>   5 files changed, 67 insertions(+), 33 deletions(-)
>>>   create mode 100644 drivers/of/kexec.c
>>>
>>> diff --git a/arch/powerpc/include/asm/kexec.h 
>>> b/arch/powerpc/include/asm/kexec.h
>>> index 55d6ede30c19..7c223031ecdd 100644
>>> --- a/arch/powerpc/include/asm/kexec.h
>>> +++ b/arch/powerpc/include/asm/kexec.h
>>> @@ -126,7 +126,6 @@ int setup_purgatory(struct kimage *image, const 
>>> void *slave_code,
>>>   int setup_new_fdt(const struct kimage *image, void *fdt,
>>>             unsigned long initrd_load_addr, unsigned long initrd_len,
>>>             const char *cmdline);
>>> -int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long 
>>> size);
>>>   #ifdef CONFIG_PPC64
>>>   struct kexec_buf;
>>> diff --git a/arch/powerpc/kexec/file_load.c 
>>> b/arch/powerpc/kexec/file_load.c
>>> index 9a232bc36c8f..9efc98b1e2ae 100644
>>> --- a/arch/powerpc/kexec/file_load.c
>>> +++ b/arch/powerpc/kexec/file_load.c
>>> @@ -109,38 +109,6 @@ int setup_purgatory(struct kimage *image, const 
>>> void *slave_code,
>>>       return 0;
>>>   }
>>> -/**
>>> - * delete_fdt_mem_rsv - delete memory reservation with given address 
>>> and size
>>> - *
>>> - * Return: 0 on success, or negative errno on error.
>>> - */
>>> -int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long 
>>> size)
>>> -{
>>> -    int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
>>> -
>>> -    for (i = 0; i < num_rsvs; i++) {
>>> -        uint64_t rsv_start, rsv_size;
>>> -
>>> -        ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
>>> -        if (ret) {
>>> -            pr_err("Malformed device tree.\n");
>>> -            return -EINVAL;
>>> -        }
>>> -
>>> -        if (rsv_start == start && rsv_size == size) {
>>> -            ret = fdt_del_mem_rsv(fdt, i);
>>> -            if (ret) {
>>> -                pr_err("Error deleting device tree reservation.\n");
>>> -                return -EINVAL;
>>> -            }
>>> -
>>> -            return 0;
>>> -        }
>>> -    }
>>> -
>>> -    return -ENOENT;
>>> -}
>>> -
>>>   /*
>>>    * setup_new_fdt - modify /chosen and memory reservation for the 
>>> next kernel
>>>    * @image:        kexec image being loaded.
>>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
>>> index 6e1e5212f058..77d24712c0c8 100644
>>> --- a/drivers/of/Makefile
>>> +++ b/drivers/of/Makefile
>>> @@ -13,5 +13,6 @@ obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
>>>   obj-$(CONFIG_OF_RESOLVE)  += resolver.o
>>>   obj-$(CONFIG_OF_OVERLAY) += overlay.o
>>>   obj-$(CONFIG_OF_NUMA) += of_numa.o
>>> +obj-$(CONFIG_OF_FLATTREE) += kexec.o
>>
>> Isn't this too broad? kexec.o will only be useful to kernel configs
>> which enable CONFIG_KEXEC_FILE, so perhaps do:
>>
>> ifdef CONFIG_OF_FLATTREE
>> ifdef CONFIG_KEXEC_FILE
>> obj-y += kexec.o
>> endif
>> endif
>>
>> What do you think?
> 
> Per Rob's feedback on v9 patch set, I have moved all the architecture 
> independent ima kexec functions to a single file "drivers/of/kexec.c"
> 
> Since these functions are enabled on different kernel CONFIGs, I have 
> used IS_ENABLED(CONFIG_XYZ) macro instead of "#ifdef" in the C file to 
> conditionally compile.
Per Rob's feedback on the v9 patch, I'll keep the ima kexec functions in 
a single file (in "drivers/of/kexec.c") and use IS_ENABLED() macro to 
handle the function calls.

I'll make the other changes you'd suggested on v10 patches and will post 
v11 patch set shortly.

thanks,
  -lakshmi

> 
>>
>>>   obj-$(CONFIG_OF_UNITTEST) += unittest-data/
>>> diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c
>>> new file mode 100644
>>> index 000000000000..b7d59105fcb8
>>> --- /dev/null
>>> +++ b/drivers/of/kexec.c
>>> @@ -0,0 +1,61 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Copyright (C) 2020 Microsoft Corporation
>>> + *
>>> + * Author: Lakshmi Ramasubramanian (nramas@...ux.microsoft.com)
>>> + *
>>> + * File: kexec.c
>>> + *    Defines kexec related functions.
>>> + */
>>> +
>>> +#define pr_fmt(fmt)    "OF: kexec: " fmt
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/memblock.h>
>>> +#include <linux/kexec.h>
>>> +#include <linux/of.h>
>>> +#include <linux/of_fdt.h>
>>> +#include <linux/libfdt.h>
>>> +
>>> +/**
>>> + * delete_fdt_mem_rsv - delete memory reservation with given address 
>>> and size
>>> + *
>>> + * @fdt: Flattened Device Tree to update
>>> + * @start: Starting address of the reservation to delete
>>> + * @size: Size of the reservation to delete
>>> + *
>>> + * Return: 0 on success, or negative errno on error.
>>> + */
>>> +int delete_fdt_mem_rsv(void *fdt, unsigned long start, unsigned long 
>>> size)
>>> +{
>>> +    int i, ret, num_rsvs;
>>> +
>>> +    if (!IS_ENABLED(CONFIG_KEXEC_FILE))
>>> +        return 0;
>>
>> If you agree with my suggestion, then this IS_ENABLED() wouldn't be
>> needed.
>>
> 
> Please see my response above.
> 
> If there is a way to keep all the ima kexec functions in a single file 
> and yet not use "#ifdef" in C file to conditionally compile, please let 
> me know. I'll update.
> 
> thanks,
>   -lakshmi
> 
>>> +
>>> +    num_rsvs = fdt_num_mem_rsv(fdt);
>>> +    for (i = 0; i < num_rsvs; i++) {
>>> +        uint64_t rsv_start, rsv_size;
>>> +
>>> +        ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
>>> +        if (ret) {
>>> +            pr_err("Malformed device tree.\n");
>>> +            return -EINVAL;
>>> +        }
>>> +
>>> +        if (rsv_start == start && rsv_size == size) {
>>> +            ret = fdt_del_mem_rsv(fdt, i);
>>> +            if (ret) {
>>> +                pr_err("Error deleting device tree reservation.\n");
>>> +                return -EINVAL;
>>> +            }
>>> +
>>> +            pr_debug("Freed reserved memory at %lu of size %lu\n",
>>> +                 start, size);
>>> +            return 0;
>>> +        }
>>> +    }
>>> +
>>> +    return -ENOENT;
>>> +}
>>
>> The function code is unchanged apart from the addition of the
>> IS_ENABLED() and the pr_debug(), so that is good.
>>
>>> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
>>> index 9e93bef52968..d0234c4815da 100644
>>> --- a/include/linux/kexec.h
>>> +++ b/include/linux/kexec.h
>>> @@ -407,6 +407,11 @@ static inline int kexec_crash_loaded(void) { 
>>> return 0; }
>>>   #define kexec_in_progress false
>>>   #endif /* CONFIG_KEXEC_CORE */
>>> +#if defined(CONFIG_OF_FLATTREE)
>>
>> This would also change to require CONFIG_KEXEC_FILE.
>>
>>> +extern int delete_fdt_mem_rsv(void *fdt, unsigned long start,
>>> +                  unsigned long size);
>>> +#endif /* CONFIG_OF_FLATTREE */
>>> +
>>>   #endif /* !defined(__ASSEBMLY__) */
>>>   #endif /* LINUX_KEXEC_H */
>>
>>

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