Re: [PATCH v3] sh: Restructure setup code to reserve memory regions earlier

On 7/11/2024 4:07 AM, John Paul Adrian Glaubitz wrote:
> Hi Oreoluwa,
>
> On Mon, 2024-05-20 at 10:58 -0700, Oreoluwa Babatunde wrote:
>> The unflatten_device_tree() function contains a call to
>> memblock_alloc(). This is a problem because this allocation is done
>> before any of the reserved memory regions are set aside in
>> paging_init().
>> As a result, there is a possibility for memblock to unknowingly allocate
>> from any of the memory regions that are meant to be reserved.
>>
>> Hence, restructure the setup code to set aside reserved memory
>> regions before any allocations are done using memblock.
>>
>> Signed-off-by: Oreoluwa Babatunde <[email protected]>
>> ---
>> v3:
>> - Instead of moving all of paging_init(), move only the parts
>>   that are responsible for setting aside the reserved memory
>>   regions.
>>
>> v2:
>> https://lore.kernel.org/all/[email protected]/
>> - Added Rob Herrings Reviewed-by.
>> - cc Andrew Morton to assist with merging this for sh architecture.
>>   Similar change made for loongarch and openrisc in v1 have already
>>   been merged.
>>
>> v1:
>> https://lore.kernel.org/all/[email protected]/
>>
>>  arch/sh/include/asm/setup.h |  1 -
>>  arch/sh/kernel/setup.c      | 43 +++++++++++++++++++++++++++++++++++-
>>  arch/sh/mm/init.c           | 44 -------------------------------------
>>  3 files changed, 42 insertions(+), 46 deletions(-)
>>
>> diff --git a/arch/sh/include/asm/setup.h b/arch/sh/include/asm/setup.h
>> index fc807011187f..5feed99b9b7a 100644
>> --- a/arch/sh/include/asm/setup.h
>> +++ b/arch/sh/include/asm/setup.h
>> @@ -19,7 +19,6 @@
>>  #define COMMAND_LINE ((char *) (PARAM+0x100))
>>  
>>  void sh_mv_setup(void);
>> -void check_for_initrd(void);
>>  void per_cpu_trap_init(void);
>>  
>>  #endif /* _SH_SETUP_H */
>> diff --git a/arch/sh/kernel/setup.c b/arch/sh/kernel/setup.c
>> index 620e5cf8ae1e..f5b6078173c9 100644
>> --- a/arch/sh/kernel/setup.c
>> +++ b/arch/sh/kernel/setup.c
>> @@ -114,7 +114,7 @@ static int __init early_parse_mem(char *p)
>>  }
>>  early_param("mem", early_parse_mem);
>>  
>> -void __init check_for_initrd(void)
>> +static void __init check_for_initrd(void)
>>  {
>>  #ifdef CONFIG_BLK_DEV_INITRD
>>  	unsigned long start, end;
>> @@ -172,6 +172,42 @@ void __init check_for_initrd(void)
>>  #endif
>>  }
>>  
>> +static void __init early_reserve_mem(void)
>> +{
>> +	unsigned long start_pfn;
>> +	u32 zero_base = (u32)__MEMORY_START + (u32)PHYSICAL_OFFSET;
>> +	u32 start = zero_base + (u32)CONFIG_ZERO_PAGE_OFFSET;
>> +
>> +	/*
>> +	 * Partially used pages are not usable - thus
>> +	 * we are rounding upwards:
>> +	 */
>> +	start_pfn = PFN_UP(__pa(_end));
>> +
>> +	/*
>> +	 * Reserve the kernel text and Reserve the bootmem bitmap. We do
>> +	 * this in two steps (first step was init_bootmem()), because
>> +	 * this catches the (definitely buggy) case of us accidentally
>> +	 * initializing the bootmem allocator with an invalid RAM area.
>> +	 */
>> +	memblock_reserve(start, (PFN_PHYS(start_pfn) + PAGE_SIZE - 1) - start);
>> +
>> +	/*
>> +	 * Reserve physical pages below CONFIG_ZERO_PAGE_OFFSET.
>> +	 */
>> +	if (CONFIG_ZERO_PAGE_OFFSET != 0)
>> +		memblock_reserve(zero_base, CONFIG_ZERO_PAGE_OFFSET);
>> +
>> +	/*
>> +	 * Handle additional early reservations
>> +	 */
>> +	check_for_initrd();
>> +	reserve_crashkernel();
>> +
>> +	if (sh_mv.mv_mem_reserve)
>> +		sh_mv.mv_mem_reserve();
>> +}
>> +
>>  #ifndef CONFIG_GENERIC_CALIBRATE_DELAY
>>  void calibrate_delay(void)
>>  {
>> @@ -319,9 +355,14 @@ void __init setup_arch(char **cmdline_p)
>>  
>>  	sh_mv_setup();
>>  
>> +	sh_mv.mv_mem_init();
>> +
>>  	/* Let earlyprintk output early console messages */
>>  	sh_early_platform_driver_probe("earlyprintk", 1, 1);
>>  
>> +	/* set aside reserved memory regions */
>> +	early_reserve_mem();
>> +
>>  #ifdef CONFIG_OF_EARLY_FLATTREE
>>  #ifdef CONFIG_USE_BUILTIN_DTB
>>  	unflatten_and_copy_device_tree();
>> diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
>> index bf1b54055316..4559f5bea782 100644
>> --- a/arch/sh/mm/init.c
>> +++ b/arch/sh/mm/init.c
>> @@ -242,55 +242,11 @@ static void __init do_init_bootmem(void)
>>  	sparse_init();
>>  }
>>  
>> -static void __init early_reserve_mem(void)
>> -{
>> -	unsigned long start_pfn;
>> -	u32 zero_base = (u32)__MEMORY_START + (u32)PHYSICAL_OFFSET;
>> -	u32 start = zero_base + (u32)CONFIG_ZERO_PAGE_OFFSET;
>> -
>> -	/*
>> -	 * Partially used pages are not usable - thus
>> -	 * we are rounding upwards:
>> -	 */
>> -	start_pfn = PFN_UP(__pa(_end));
>> -
>> -	/*
>> -	 * Reserve the kernel text and Reserve the bootmem bitmap. We do
>> -	 * this in two steps (first step was init_bootmem()), because
>> -	 * this catches the (definitely buggy) case of us accidentally
>> -	 * initializing the bootmem allocator with an invalid RAM area.
>> -	 */
>> -	memblock_reserve(start, (PFN_PHYS(start_pfn) + PAGE_SIZE - 1) - start);
>> -
>> -	/*
>> -	 * Reserve physical pages below CONFIG_ZERO_PAGE_OFFSET.
>> -	 */
>> -	if (CONFIG_ZERO_PAGE_OFFSET != 0)
>> -		memblock_reserve(zero_base, CONFIG_ZERO_PAGE_OFFSET);
>> -
>> -	/*
>> -	 * Handle additional early reservations
>> -	 */
>> -	check_for_initrd();
>> -	reserve_crashkernel();
>> -}
>> -
>>  void __init paging_init(void)
>>  {
>>  	unsigned long max_zone_pfns[MAX_NR_ZONES];
>>  	unsigned long vaddr, end;
>>  
>> -	sh_mv.mv_mem_init();
>> -
>> -	early_reserve_mem();
>> -
>> -	/*
>> -	 * Once the early reservations are out of the way, give the
>> -	 * platforms a chance to kick out some memory.
>> -	 */
>> -	if (sh_mv.mv_mem_reserve)
>> -		sh_mv.mv_mem_reserve();
>> -
>>  	memblock_enforce_memory_limit(memory_limit);
>>  	memblock_allow_resize();
>>  
> This is missing an include of <asm/kexec.h> in arch/sh/kernel/setup.c:
>
>   CC      io_uring/notif.o
>   CC      lib/zlib_inflate/inftrees.o
> arch/sh/kernel/setup.c: In function 'early_reserve_mem':
> arch/sh/kernel/setup.c:205:9: error: implicit declaration of function 'reserve_crashkernel'; did you mean 'parse_crashkernel'? [-Werror=implicit-function-declaration]
>   205 |         reserve_crashkernel();
>       |         ^~~~~~~~~~~~~~~~~~~
>       |         parse_crashkernel
>   CC      net/core/flow_dissector.o
>   AR      block/partitions/built-in.a
>   CC      block/elevator.o
>   CC      block/blk-core.o
> cc1: some warnings being treated as errors
>   CC      crypto/shash.o
> make[4]: *** [scripts/Makefile.build:244: arch/sh/kernel/setup.o] Error 1
> make[4]: *** Waiting for unfinished jobs....
>   CC      crypto/crc32c_generic.o
>
> Can you fix that? And, while at it, also rebase the patch against v6.10-rc1
> so it applies cleanly against my SH Linux tree?
>
> Besides, I have tested the patch and I can confirm that my J2 board still
> boots fine with the patch applied.
>
> Sorry for being so super-late with the review. I hope you can still send
> an updated patch by tomorrow or Saturday.
>
> Adrian
Hi Adrian,

Thanks for taking a look and testing the patch!

I have made the changes you mentioned and
uploaded the new version of the patch here:
https://lore.kernel.org/all/[email protected]/

Please let me know if you need me to do anything else.

Regards,
Oreoluwa