2021-02-19 14:30:10

by Thiago Jung Bauermann

[permalink] [raw]
Subject: [PATCH] powerpc/kexec_file: Restore FDT size estimation for kdump kernel

Commit 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump
kernel") fixed how elf64_load() estimates the FDT size needed by the
crashdump kernel.

At the same time, commit 130b2d59cec0 ("powerpc: Use common
of_kexec_alloc_and_setup_fdt()") changed the same code to use the generic
function of_kexec_alloc_and_setup_fdt() to calculate the FDT size. That
change made the code overestimate it a bit by counting twice the space
required for the kernel command line and /chosen properties.

Therefore change kexec_fdt_totalsize_ppc64() to calculate just the extra
space needed by the kdump kernel, and change the function name so that it
better reflects what the function is now doing.

Signed-off-by: Thiago Jung Bauermann <[email protected]>
---
arch/powerpc/include/asm/kexec.h | 2 +-
arch/powerpc/kexec/elf_64.c | 2 +-
arch/powerpc/kexec/file_load_64.c | 26 ++++++++------------------
3 files changed, 10 insertions(+), 20 deletions(-)

Applies on top of next-20210219.

diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
index baab158e215c..5a11cc8d2350 100644
--- a/arch/powerpc/include/asm/kexec.h
+++ b/arch/powerpc/include/asm/kexec.h
@@ -128,7 +128,7 @@ int load_crashdump_segments_ppc64(struct kimage *image,
int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
const void *fdt, unsigned long kernel_load_addr,
unsigned long fdt_load_addr);
-unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image);
+unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image);
int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
unsigned long initrd_load_addr,
unsigned long initrd_len, const char *cmdline);
diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 0492ca6003f3..5a569bb51349 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -104,7 +104,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,

fdt = of_kexec_alloc_and_setup_fdt(image, initrd_load_addr,
initrd_len, cmdline,
- kexec_fdt_totalsize_ppc64(image));
+ kexec_extra_fdt_size_ppc64(image));
if (!fdt) {
pr_err("Error setting up the new device tree.\n");
ret = -EINVAL;
diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
index 3609de30a170..8541ba731908 100644
--- a/arch/powerpc/kexec/file_load_64.c
+++ b/arch/powerpc/kexec/file_load_64.c
@@ -927,37 +927,27 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
}

/**
- * kexec_fdt_totalsize_ppc64 - Return the estimated size needed to setup FDT
- * for kexec/kdump kernel.
- * @image: kexec image being loaded.
+ * kexec_extra_fdt_size_ppc63 - Return the estimated size needed to setup FDT
+ * for kexec/kdump kernel.
+ * @image: kexec image being loaded.
*
- * Returns the estimated size needed for kexec/kdump kernel FDT.
+ * Returns the estimated extra size needed for kexec/kdump kernel FDT.
*/
-unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
+unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image)
{
- unsigned int fdt_size;
u64 usm_entries;

- /*
- * The below estimate more than accounts for a typical kexec case where
- * the additional space is to accommodate things like kexec cmdline,
- * chosen node with properties for initrd start & end addresses and
- * a property to indicate kexec boot..
- */
- fdt_size = fdt_totalsize(initial_boot_params) + (2 * COMMAND_LINE_SIZE);
if (image->type != KEXEC_TYPE_CRASH)
- return fdt_size;
+ return 0;

/*
- * For kdump kernel, also account for linux,usable-memory and
+ * For kdump kernel, account for linux,usable-memory and
* linux,drconf-usable-memory properties. Get an approximate on the
* number of usable memory entries and use for FDT size estimation.
*/
usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) +
(2 * (resource_size(&crashk_res) / drmem_lmb_size())));
- fdt_size += (unsigned int)(usm_entries * sizeof(u64));
-
- return fdt_size;
+ return (unsigned int)(usm_entries * sizeof(u64));
}

/**


2021-02-19 16:02:40

by Lakshmi Ramasubramanian

[permalink] [raw]
Subject: Re: [PATCH] powerpc/kexec_file: Restore FDT size estimation for kdump kernel

On 2/19/21 6:25 AM, Thiago Jung Bauermann wrote:

One small nit in the function header (please see below), but otherwise
the change looks good.

Reviewed-by: Lakshmi Ramasubramanian <[email protected]>

> Commit 2377c92e37fe ("powerpc/kexec_file: fix FDT size estimation for kdump
> kernel") fixed how elf64_load() estimates the FDT size needed by the
> crashdump kernel.
>
> At the same time, commit 130b2d59cec0 ("powerpc: Use common
> of_kexec_alloc_and_setup_fdt()") changed the same code to use the generic
> function of_kexec_alloc_and_setup_fdt() to calculate the FDT size. That
> change made the code overestimate it a bit by counting twice the space
> required for the kernel command line and /chosen properties.
>
> Therefore change kexec_fdt_totalsize_ppc64() to calculate just the extra
> space needed by the kdump kernel, and change the function name so that it
> better reflects what the function is now doing.
>
> Signed-off-by: Thiago Jung Bauermann <[email protected]>
> ---
> arch/powerpc/include/asm/kexec.h | 2 +-
> arch/powerpc/kexec/elf_64.c | 2 +-
> arch/powerpc/kexec/file_load_64.c | 26 ++++++++------------------
> 3 files changed, 10 insertions(+), 20 deletions(-)
>
> Applies on top of next-20210219.
>
> diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
> index baab158e215c..5a11cc8d2350 100644
> --- a/arch/powerpc/include/asm/kexec.h
> +++ b/arch/powerpc/include/asm/kexec.h
> @@ -128,7 +128,7 @@ int load_crashdump_segments_ppc64(struct kimage *image,
> int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
> const void *fdt, unsigned long kernel_load_addr,
> unsigned long fdt_load_addr);
> -unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image);
> +unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image);
> int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
> unsigned long initrd_load_addr,
> unsigned long initrd_len, const char *cmdline);
> diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
> index 0492ca6003f3..5a569bb51349 100644
> --- a/arch/powerpc/kexec/elf_64.c
> +++ b/arch/powerpc/kexec/elf_64.c
> @@ -104,7 +104,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>
> fdt = of_kexec_alloc_and_setup_fdt(image, initrd_load_addr,
> initrd_len, cmdline,
> - kexec_fdt_totalsize_ppc64(image));
> + kexec_extra_fdt_size_ppc64(image));
> if (!fdt) {
> pr_err("Error setting up the new device tree.\n");
> ret = -EINVAL;
> diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> index 3609de30a170..8541ba731908 100644
> --- a/arch/powerpc/kexec/file_load_64.c
> +++ b/arch/powerpc/kexec/file_load_64.c
> @@ -927,37 +927,27 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
> }
>
> /**
> - * kexec_fdt_totalsize_ppc64 - Return the estimated size needed to setup FDT
> - * for kexec/kdump kernel.
> - * @image: kexec image being loaded.
> + * kexec_extra_fdt_size_ppc63 - Return the estimated size needed to setup FDT

Perhaps change to

"Return the estimated additional size needed to setup FDT for
kexec/kdump kernel"?

-lakshmi

> + * for kexec/kdump kernel.
> + * @image: kexec image being loaded.
> *
> - * Returns the estimated size needed for kexec/kdump kernel FDT.
> + * Returns the estimated extra size needed for kexec/kdump kernel FDT.
> */
> -unsigned int kexec_fdt_totalsize_ppc64(struct kimage *image)
> +unsigned int kexec_extra_fdt_size_ppc64(struct kimage *image)
> {
> - unsigned int fdt_size;
> u64 usm_entries;
>
> - /*
> - * The below estimate more than accounts for a typical kexec case where
> - * the additional space is to accommodate things like kexec cmdline,
> - * chosen node with properties for initrd start & end addresses and
> - * a property to indicate kexec boot..
> - */
> - fdt_size = fdt_totalsize(initial_boot_params) + (2 * COMMAND_LINE_SIZE);
> if (image->type != KEXEC_TYPE_CRASH)
> - return fdt_size;
> + return 0;
>
> /*
> - * For kdump kernel, also account for linux,usable-memory and
> + * For kdump kernel, account for linux,usable-memory and
> * linux,drconf-usable-memory properties. Get an approximate on the
> * number of usable memory entries and use for FDT size estimation.
> */
> usm_entries = ((memblock_end_of_DRAM() / drmem_lmb_size()) +
> (2 * (resource_size(&crashk_res) / drmem_lmb_size())));
> - fdt_size += (unsigned int)(usm_entries * sizeof(u64));
> -
> - return fdt_size;
> + return (unsigned int)(usm_entries * sizeof(u64));
> }
>
> /**
>

2021-02-19 23:44:16

by Thiago Jung Bauermann

[permalink] [raw]
Subject: Re: [PATCH] powerpc/kexec_file: Restore FDT size estimation for kdump kernel


Lakshmi Ramasubramanian <[email protected]> writes:

> On 2/19/21 6:25 AM, Thiago Jung Bauermann wrote:
>
> One small nit in the function header (please see below), but otherwise the
> change looks good.
>
> Reviewed-by: Lakshmi Ramasubramanian <[email protected]>

Thanks for your review. I incorporated your suggestion and will send v2
shortly.

>> --- a/arch/powerpc/kexec/file_load_64.c
>> +++ b/arch/powerpc/kexec/file_load_64.c
>> @@ -927,37 +927,27 @@ int setup_purgatory_ppc64(struct kimage *image, const void *slave_code,
>> }
>> /**
>> - * kexec_fdt_totalsize_ppc64 - Return the estimated size needed to setup FDT
>> - * for kexec/kdump kernel.
>> - * @image: kexec image being loaded.
>> + * kexec_extra_fdt_size_ppc63 - Return the estimated size needed to setup FDT
>
> Perhaps change to
>
> "Return the estimated additional size needed to setup FDT for kexec/kdump
> kernel"?

That's better indeed. I also hadn't noticed that I changed ppc64 to
ppc63. Fixed as well.

--
Thiago Jung Bauermann
IBM Linux Technology Center