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Date: Thu, 30 Nov 2023 14:54:24 -0600
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Subject: Re: [PATCH 1/2] kexec: fix KEXEC_FILE dependencies
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To: Andrew Morton <akpm@linux-foundation.org>, Baoquan He <bhe@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Vivek Goyal <vgoyal@redhat.com>,
 linux-kernel@vger.kernel.org, kexec@lists.infradead.org, x86@kernel.org,
 linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
 linux-s390@vger.kernel.org, linux-crypto@vger.kernel.org
References: <20231023110308.1202042-1-arnd@kernel.org>
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 <20231130085657.6f7f500cc17b663747e4ee76@linux-foundation.org>
From: Eric DeVolder <eric_devolder@yahoo.com>
In-Reply-To: <20231130085657.6f7f500cc17b663747e4ee76@linux-foundation.org>
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On 11/30/23 10:56, Andrew Morton wrote:
> On Thu, 2 Nov 2023 16:03:18 +0800 Baoquan He <bhe@redhat.com> wrote:
>
>>>> CONFIG_KEXEC_FILE, but still get purgatory code built in which is
>>>> totally useless.
>>>>
>>>> Not sure if I think too much over this.
>>> I see your point here, and I would suggest changing the
>>> CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY symbol to just indicate
>>> the availability of the purgatory code for the arch, rather
>>> than actually controlling the code itself. I already mentioned
>>> this for s390, but riscv would need the same thing on top.
>>>
>>> I think the change below should address your concern.
>> Since no new comment, do you mind spinning v2 to wrap all these up?
> This patchset remains in mm-hotfixes-unstable from the previous -rc
> cycle.  Eric, do you have any comments?  Arnd, do you plan on a v2?  If
> not, should I merge v1?  If so, should I now add cc:stable?

My apologies, I lost this. I've looked at these changes, and I am in 
favor of these changes.

Furthermore, I ran the following thru the Kconfig regression script, and 
did not find anything!

I believe the following patch represents the current discussion threads 
around Kconfig and KEXEC/CRASH.

Reviewed-by: Eric DeVolder <eric_devolder@yahoo.com>

Tested-by: Eric DeVolder <eric_devolder@yahoo.com>

Thanks!

eric

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6f105ee4f3cf..1f11a62809f2 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -608,10 +608,10 @@ config ARCH_SUPPORTS_KEXEC
      def_bool PPC_BOOK3S || PPC_E500 || (44x && !SMP)

  config ARCH_SUPPORTS_KEXEC_FILE
-    def_bool PPC64 && CRYPTO=y && CRYPTO_SHA256=y
+    def_bool PPC64

  config ARCH_SUPPORTS_KEXEC_PURGATORY
-    def_bool KEXEC_FILE
+    def_bool y

  config ARCH_SELECTS_KEXEC_FILE
      def_bool y
diff --git a/arch/riscv/Kbuild b/arch/riscv/Kbuild
index d25ad1c19f88..ab181d187c23 100644
--- a/arch/riscv/Kbuild
+++ b/arch/riscv/Kbuild
@@ -5,7 +5,7 @@ obj-$(CONFIG_BUILTIN_DTB) += boot/dts/
  obj-y += errata/
  obj-$(CONFIG_KVM) += kvm/

-obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
+obj-$(CONFIG_KEXEC_FILE) += purgatory/

  # for cleaning
  subdir- += boot
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 95a2a06acc6a..98857d76e458 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -702,9 +702,7 @@ config ARCH_SELECTS_KEXEC_FILE
      select KEXEC_ELF

  config ARCH_SUPPORTS_KEXEC_PURGATORY
-    def_bool KEXEC_FILE
-    depends on CRYPTO=y
-    depends on CRYPTO_SHA256=y
+    def_bool y

  config ARCH_SUPPORTS_CRASH_DUMP
      def_bool y
diff --git a/arch/riscv/kernel/elf_kexec.c b/arch/riscv/kernel/elf_kexec.c
index e60fbd8660c4..3ac341d296db 100644
--- a/arch/riscv/kernel/elf_kexec.c
+++ b/arch/riscv/kernel/elf_kexec.c
@@ -266,7 +266,7 @@ static void *elf_kexec_load(struct kimage *image, 
char *kernel_buf,
          cmdline = modified_cmdline;
      }

-#ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY
+#ifdef CONFIG_KEXEC_FILE
      /* Add purgatory to the image */
      kbuf.top_down = true;
      kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
@@ -280,7 +280,7 @@ static void *elf_kexec_load(struct kimage *image, 
char *kernel_buf,
                           sizeof(kernel_start), 0);
      if (ret)
          pr_err("Error update purgatory ret=%d\n", ret);
-#endif /* CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY */
+#endif /* CONFIG_KEXEC_FILE */

      /* Add the initrd to the image */
      if (initrd != NULL) {
diff --git a/arch/s390/Kbuild b/arch/s390/Kbuild
index a5d3503b353c..f2ce80b65551 100644
--- a/arch/s390/Kbuild
+++ b/arch/s390/Kbuild
@@ -7,7 +7,7 @@ obj-$(CONFIG_S390_HYPFS)    += hypfs/
  obj-$(CONFIG_APPLDATA_BASE)    += appldata/
  obj-y                += net/
  obj-$(CONFIG_PCI)        += pci/
-obj-$(CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY) += purgatory/
+obj-$(CONFIG_KEXEC_FILE) += purgatory/

  # for cleaning
  subdir- += boot tools
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3bec98d20283..d5d8f99d1f25 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -254,13 +254,13 @@ config ARCH_SUPPORTS_KEXEC
      def_bool y

  config ARCH_SUPPORTS_KEXEC_FILE
-    def_bool CRYPTO && CRYPTO_SHA256 && CRYPTO_SHA256_S390
+    def_bool y

  config ARCH_SUPPORTS_KEXEC_SIG
      def_bool MODULE_SIG_FORMAT

  config ARCH_SUPPORTS_KEXEC_PURGATORY
-    def_bool KEXEC_FILE
+    def_bool y

  config ARCH_SUPPORTS_CRASH_DUMP
      def_bool y
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3762f41bb092..1566748f16c4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2072,7 +2072,7 @@ config ARCH_SUPPORTS_KEXEC
      def_bool y

  config ARCH_SUPPORTS_KEXEC_FILE
-    def_bool X86_64 && CRYPTO && CRYPTO_SHA256
+    def_bool X86_64

  config ARCH_SELECTS_KEXEC_FILE
      def_bool y
@@ -2080,7 +2080,7 @@ config ARCH_SELECTS_KEXEC_FILE
      select HAVE_IMA_KEXEC if IMA

  config ARCH_SUPPORTS_KEXEC_PURGATORY
-    def_bool KEXEC_FILE
+    def_bool y

  config ARCH_SUPPORTS_KEXEC_SIG
      def_bool y
diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
index 7aff28ded2f4..92120e396008 100644
--- a/kernel/Kconfig.kexec
+++ b/kernel/Kconfig.kexec
@@ -36,6 +36,7 @@ config KEXEC
  config KEXEC_FILE
      bool "Enable kexec file based system call"
      depends on ARCH_SUPPORTS_KEXEC_FILE
+    depends on CRYPTO_SHA256=y || !ARCH_SUPPORTS_KEXEC_PURGATORY
      select KEXEC_CORE
      help
        This is new version of kexec system call. This system call is
@@ -94,10 +95,8 @@ config KEXEC_JUMP
  config CRASH_DUMP
      bool "kernel crash dumps"
      depends on ARCH_SUPPORTS_CRASH_DUMP
-    depends on ARCH_SUPPORTS_KEXEC
      select CRASH_CORE
      select KEXEC_CORE
-    select KEXEC
      help
        Generate crash dump after being started by kexec.
        This should be normally only set in special crash dump kernels