On Fri, 2021-02-19 at 11:08 -0300, Thiago Jung Bauermann wrote:

Lakshmi Ramasubramanian [off-list ref] writes:

quoted

On 2/18/21 5:13 PM, Thiago Jung Bauermann wrote:

quoted

Lakshmi Ramasubramanian [off-list ref] writes:

quoted

On 2/18/21 4:07 PM, Mimi Zohar wrote:

Hi Mimi,

quoted

On Thu, 2021-02-18 at 14:33 -0800, Lakshmi Ramasubramanian wrote:

quoted

of_kexec_alloc_and_setup_fdt() defined in drivers/of/kexec.c builds
a new device tree object that includes architecture specific data
for kexec system call.  This should be defined only if the architecture
being built defines kexec architecture structure "struct kimage_arch".

Define a new boolean config OF_KEXEC that is enabled if
CONFIG_KEXEC_FILE and CONFIG_OF_FLATTREE are enabled, and
the architecture is arm64 or powerpc64.  Build drivers/of/kexec.c
if CONFIG_OF_KEXEC is enabled.

Signed-off-by: Lakshmi Ramasubramanian <redacted>
Fixes: 33488dc4d61f ("of: Add a common kexec FDT setup function")
Reported-by: kernel test robot <redacted>
---
   drivers/of/Kconfig  | 6 ++++++
   drivers/of/Makefile | 7 +------
   2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 18450437d5d5..f2e8fa54862a 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig

@@ -100,4 +100,10 @@ config OF_DMA_DEFAULT_COHERENT
   	# arches should select this if DMA is coherent by default for OF devices
   	bool
   +config OF_KEXEC
+	bool
+	depends on KEXEC_FILE
+	depends on OF_FLATTREE
+	default y if ARM64 || PPC64
+
   endif # OF

diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index c13b982084a3..287579dd1695 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile

@@ -13,11 +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
-
-ifdef CONFIG_KEXEC_FILE
-ifdef CONFIG_OF_FLATTREE
-obj-y	+= kexec.o
-endif
-endif
+obj-$(CONFIG_OF_KEXEC) += kexec.o
     obj-$(CONFIG_OF_UNITTEST) += unittest-data/

Is it possible to reuse CONFIG_HAVE_IMA_KEXEC here?

For ppc64 CONFIG_HAVE_IMA_KEXEC is selected when CONFIG_KEXEC_FILE is enabled.
So I don't see a problem in reusing CONFIG_HAVE_IMA_KEXEC for ppc.

But for arm64, CONFIG_HAVE_IMA_KEXEC is enabled in the final patch in the patch
set (the one for carrying forward IMA log across kexec for arm64). arm64 calls
of_kexec_alloc_and_setup_fdt() prior to enabling CONFIG_HAVE_IMA_KEXEC and hence
breaks the build for arm64.

One problem is that I believe that this patch won't placate the robot,
because IIUC it generates config files at random and this change still
allows hppa and s390 to enable CONFIG_OF_KEXEC.

I enabled CONFIG_OF_KEXEC for s390. With my patch applied, CONFIG_OF_KEXEC is
removed. So I think the robot enabling this config would not be a problem.

quoted

Perhaps a new CONFIG_HAVE_KIMAGE_ARCH option? Not having that option
would still allow building kexec.o, but would be used inside kexec.c to
avoid accessing kimage.arch members.

I think this is a good idea - a new CONFIG_HAVE_KIMAGE_ARCH, which will be
selected by arm64 and ppc for now. I tried this, and it fixes the build issue.

Although, the name for the new config can be misleading since PARISC, for
instance, also defines "struct kimage_arch". Perhaps,
CONFIG_HAVE_ELF_KIMAGE_ARCH since of_kexec_alloc_and_setup_fdt() is 
accessing ELF specific fields in "struct kimage_arch"?

Ah, right. I should have digged into the code before making my
suggestion. CONFIG_HAVE_KIMAGE_ARCH isn't appropriate, indeed.

quoted

Rob/Mimi - please let us know which approach you think is better.

Ah! We can actually use the existing CONFIG_HAVE_IMA_KEXEC, no? I don't
know why I didn't think of it before.

Including kexec.o based on CONFIG_HAVE_IMA_KEXEC is a bisect issue on
ARM64, as Lakshmi pointed out.   Defining a new, maybe temporary, flag
would solve the problem.

Mimi