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

Thiago Jung Bauermann
2020-12-05T02:24:37Z

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/

> 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?

> 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.

> +
> + 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 */

--
Thiago Jung Bauermann
IBM Linux Technology Center