linux.git/kernel/kexec_elf.c, branch v6.6.132

kexec: initialize ELF lowest address to ULONG_MAX

2025-04-10T12:37:34+00:00

[ Upstream commit 9986fb5164c8b21f6439cfd45ba36d8cc80c9710 ]

Patch series "powerpc/crash: use generic crashkernel reservation", v3.

Commit 0ab97169aa05 ("crash_core: add generic function to do reservation")
added a generic function to reserve crashkernel memory.  So let's use the
same function on powerpc and remove the architecture-specific code that
essentially does the same thing.

The generic crashkernel reservation also provides a way to split the
crashkernel reservation into high and low memory reservations, which can
be enabled for powerpc in the future.

Additionally move powerpc to use generic APIs to locate memory hole for
kexec segments while loading kdump kernel.

This patch (of 7):

kexec_elf_load() loads an ELF executable and sets the address of the
lowest PT_LOAD section to the address held by the lowest_load_addr
function argument.

To determine the lowest PT_LOAD address, a local variable lowest_addr
(type unsigned long) is initialized to UINT_MAX.  After loading each
PT_LOAD, its address is compared to lowest_addr.  If a loaded PT_LOAD
address is lower, lowest_addr is updated.  However, setting lowest_addr to
UINT_MAX won't work when the kernel image is loaded above 4G, as the
returned lowest PT_LOAD address would be invalid.  This is resolved by
initializing lowest_addr to ULONG_MAX instead.

This issue was discovered while implementing crashkernel high/low
reservation on the PowerPC architecture.

Link: https://lkml.kernel.org/r/20250131113830.925179-1-sourabhjain@linux.ibm.com
Link: https://lkml.kernel.org/r/20250131113830.925179-2-sourabhjain@linux.ibm.com
Fixes: a0458284f062 ("powerpc: Add support code for kexec_file_load()")
Signed-off-by: Sourabh Jain 
Acked-by: Hari Bathini 
Acked-by: Baoquan He 
Cc: Madhavan Srinivasan 
Cc: Mahesh Salgaonkar 
Cc: Michael Ellerman 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

kexec_elf: support 32 bit ELF files

2019-09-06T21:58:44+00:00

The powerpc version only supported 64 bit. Add some
code to switch decoding of fields during runtime so
we can kexec a 32 bit kernel from a 64 bit kernel and
vice versa.

Signed-off-by: Sven Schnelle 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Helge Deller

kexec_elf: remove unused variable in kexec_elf_load()

2019-09-06T21:58:44+00:00

base was never assigned, so we can remove it.

Reviewed-by: Christophe Leroy 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

kexec_elf: remove Elf_Rel macro

2019-09-06T21:58:43+00:00

It wasn't used anywhere, so lets drop it.

Reviewed-by: Christophe Leroy 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Sven Schnelle 
Signed-off-by: Helge Deller

kexec_elf: remove PURGATORY_STACK_SIZE

2019-09-06T21:58:43+00:00

It's not used anywhere so just drop it.

Signed-off-by: Sven Schnelle 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Helge Deller

kexec_elf: remove parsing of section headers

2019-09-06T21:58:43+00:00

We're not using them, so we can drop the parsing.

Signed-off-by: Sven Schnelle 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Helge Deller

kexec_elf: change order of elf_*_to_cpu() functions

2019-09-06T21:58:43+00:00

Change the order to have a 64/32/16 order, no functional change.

Signed-off-by: Sven Schnelle 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Helge Deller

kexec: add KEXEC_ELF

2019-09-06T21:58:43+00:00

Right now powerpc provides an implementation to read elf files
with the kexec_file_load() syscall. Make that available as a public
kexec interface so it can be re-used on other architectures.

Signed-off-by: Sven Schnelle 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Helge Deller