[PATCH 0/3] Getting biarch support

[PATCH 0/3] Getting biarch support

[Eric W. Biederman]

It looks like no one ever tested taking a crashdump
from a 64bit kernel with a 32bit userspace on x86,
and we have a reuse-cmdline regression fixes follow.

Eric


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[PATCH 1/3] Refix concat_cmdline

[Eric W. Biederman]

When removing the potential leak the logic was flipped which
mean we never reached the case for handling when both parameters
were set.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
 kexec/kexec.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kexec/kexec.c b/kexec/kexec.c
index d282ade..43d0189 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -1007,9 +1007,9 @@ char *concat_cmdline(const char *base, const char *append)
 	char *cmdline;
 	if (!base && !append)
 		return NULL;
-	if (append)
+	if (append && !base)
 		return xstrdup(append);
-	if (base)
+	if (base && !append)
 		return xstrdup(base);
 	cmdline = xmalloc(strlen(base) + 1 + strlen(append) + 1);
 	strcpy(cmdline, base);
-- 
1.6.6.1


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Re: [PATCH 0/3] Getting biarch support

[Simon Horman]

On Thu, Mar 11, 2010 at 12:16:58AM -0800, Eric W. Biederman wrote:
> 
> It looks like no one ever tested taking a crashdump
> from a 64bit kernel with a 32bit userspace on x86,
> and we have a reuse-cmdline regression fixes follow.

I seem to recall testing that, but it was many moons ago :-)


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[PATCH 2/3] kexec: Figure out our native architecture before load

[Eric W. Biederman]

This moves the computing of our native archtecture earlier so
that load can use it, as arch/i386/crashdump-x86.c has been
trying to.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
 kexec/kexec.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/kexec/kexec.c b/kexec/kexec.c
index 43d0189..16a0ec9 100644
--- a/kexec/kexec.c
+++ b/kexec/kexec.c
@@ -695,17 +695,19 @@ static int my_load(const char *type, int fileind, int argc, char **argv,
 			}
 		}
 	}
+	/* Figure out our native architecture before load */
+	native_arch = physical_arch();
+	if (native_arch < 0) {
+		return -1;
+	}
+	info.kexec_flags |= native_arch;
+
 	if (file_type[i].load(argc, argv, kernel_buf,
 			      kernel_size, &info) < 0) {
 		fprintf(stderr, "Cannot load %s\n", kernel);
 		return -1;
 	}
 	/* If we are not in native mode setup an appropriate trampoline */
-	native_arch = physical_arch();
-	if (native_arch < 0) {
-		return -1;
-	}
-	info.kexec_flags |= native_arch;
 	if (arch_compat_trampoline(&info) < 0) {
 		return -1;
 	}
-- 
1.6.6.1


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[PATCH 3/3] x86: Fix biarch crashdump setup.

[Eric W. Biederman]

Generate the correct crashdump header for x86_64 kernels
when a 32bit kernel is used.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
 kexec/arch/i386/crashdump-x86.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index 804dadd..9d37442 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -509,7 +509,7 @@ static struct crash_elf_info elf_info32 =
 static enum coretype get_core_type(struct kexec_info *info,
 				   struct memory_range *range, int ranges)
 {
-	if (info->kexec_flags & KEXEC_ARCH_X86_64)
+	if ((info->kexec_flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_X86_64)
 		return CORE_TYPE_ELF64;
 	else {
 		/* fall back to default */
@@ -534,6 +534,7 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 	unsigned long sz, elfcorehdr;
 	int nr_ranges, align = 1024;
 	struct memory_range *mem_range, *memmap_p;
+	unsigned machine;
 
 	if (get_crash_memory_ranges(&mem_range, &nr_ranges,
 				    info->kexec_flags) < 0)
@@ -548,6 +549,12 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 			get_core_type(info, mem_range, nr_ranges);
 	}
 
+        /* Get the elf architecture of the running kernel */
+	machine = EM_386;
+	if ((info->kexec_flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_X86_64) {
+		machine = EM_X86_64;
+	}
+
 	/* Memory regions which panic kernel can safely use to boot into */
 	sz = (sizeof(struct memory_range) * (KEXEC_MAX_SEGMENTS + 1));
 	memmap_p = xmalloc(sz);
@@ -571,6 +578,7 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 
 	/* Create elf header segment and store crash image data. */
 	if (arch_options.core_header_type == CORE_TYPE_ELF64) {
+		elf_info64.machine = machine;
 		if (crash_create_elf64_headers(info, &elf_info64,
 					       crash_memory_range, nr_ranges,
 					       &tmp, &sz,
@@ -578,6 +586,7 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 			return -1;
 	}
 	else {
+		elf_info32.machine = machine;
 		if (crash_create_elf32_headers(info, &elf_info32,
 					       crash_memory_range, nr_ranges,
 					       &tmp, &sz,
-- 
1.6.6.1


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Re: [PATCH 0/3] Getting biarch support

[Bernhard Walle]

Zitat von "Eric W. Biederman" <ebiederm@xmission.com>:

>
> It looks like no one ever tested taking a crashdump
> from a 64bit kernel with a 32bit userspace on x86,
> and we have a reuse-cmdline regression fixes follow.

I didn't even know that it is supposed to work...


Regards,
Bernhard




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Re: [PATCH 0/3] Getting biarch support

[Eric W. Biederman]

Bernhard Walle <bernhard@bwalle.de> writes:

> Zitat von "Eric W. Biederman" <ebiederm@xmission.com>:
>
>>
>> It looks like no one ever tested taking a crashdump
>> from a 64bit kernel with a 32bit userspace on x86,
>> and we have a reuse-cmdline regression fixes follow.
>
> I didn't even know that it is supposed to work...

The x86 biarch tends to be an after thought.  But we
have to do the hard work for all of the architectures
where the optimal configuration is 32bit userspace with
a 64bit kernel.  So we might as well have it work on
x86 so we can test the code without need an exotic
architecture.

In my case it was purely code size savings on an embedded
setup that got me using, and thus fixing it.

Eric

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Re: [PATCH 0/3] Getting biarch support

[Simon Horman]

On Thu, Mar 11, 2010 at 12:16:58AM -0800, Eric W. Biederman wrote:
> 
> It looks like no one ever tested taking a crashdump
> from a 64bit kernel with a 32bit userspace on x86,
> and we have a reuse-cmdline regression fixes follow.

Thanks, these patches all look good to me. I have applied and pushed them.


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