Re: [PATCH v10 2/8] powerpc: Move delete_fdt_mem_rsv() to drivers/of/kexec.c

Lakshmi Ramasubramanian
2020-12-07T01:51:41Z

On 12/4/20 6:22 PM, Thiago Jung Bauermann wrote:
>
> Hello Lakshmi,
>
> Lakshmi Ramasubramanian <nramas@linux.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@linux.microsoft.com>
>> Signed-off-by: Prakhar Srivastava <prsriva@linux.microsoft.com>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.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.

>
>> 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@linux.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 */
>
>