[PATCH v2 1/2] powerpc/fadump: allocate memory for additional parameters early

[Sourabh Jain]

Hello Venkat,

Thanks for testing the patch series.

- Sourabh Jain


On 07/11/24 19:25, Venkat Rao Bagalkote wrote:
> Applied the below patch to 6.12.0-rc6-next20241106 and issue is not 
> seen. Results look good to me.
>
> [root at ltcden8-lp5 ~]# uname -r
> 6.12.0-rc6-next-20241106-00002-gf374fbb4ee1a
> [root at ltcden8-lp5 ~]#
>
> Please add below tag.
>
> Tested-by: Venkat Rao Bagalkote <venkat88 at linux.vnet.ibm.com>
>
> On 07/11/24 11:28 am, Sourabh Jain wrote:
>> From: Hari Bathini <hbathini at linux.ibm.com>
>>
>> Memory for passing additional parameters to fadump capture kernel
>> is allocated during subsys_initcall level, using memblock. But
>> as slab is already available by this time, allocation happens via
>> the buddy allocator. This may work for radix MMU but is likely to
>> fail in most cases for hash MMU as hash MMU needs this memory in
>> the first memory block for it to be accessible in real mode in the
>> capture kernel (second boot). So, allocate memory for additional
>> parameters area as soon as MMU mode is obvious.
>>
>> Fixes: 683eab94da75 ("powerpc/fadump: setup additional parameters for 
>> dump capture kernel")
>> Reported-by: Venkat Rao Bagalkote <venkat88 at linux.vnet.ibm.com>
>> Closes: 
>> https://lore.kernel.org/lkml/a70e4064-a040-447b-8556-1fd02f19383d@linux.vnet.ibm.com/T/#u
>> Cc: Mahesh Salgaonkar <mahesh at linux.ibm.com>
>> Cc: Michael Ellerman <mpe at ellerman.id.au>
>> Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
>> Signed-off-by: Sourabh Jain <sourabhjain at linux.ibm.com>
>> ---
>>
>> Changelog:
>>
>> Since v1: 
>> https://lore.kernel.org/all/20241104083528.99520-1-sourabhjain@linux.ibm.com/
>>    - Drop extern keyword from fadump_setup_param_area function 
>> declaration
>>    - Don't use __va() while resetting param memory area
>>
>> ---
>>   arch/powerpc/include/asm/fadump.h |  2 ++
>>   arch/powerpc/kernel/fadump.c      | 15 ++++++++++-----
>>   arch/powerpc/kernel/prom.c        |  3 +++
>>   3 files changed, 15 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/fadump.h 
>> b/arch/powerpc/include/asm/fadump.h
>> index ef40c9b6972a..7b3473e05273 100644
>> --- a/arch/powerpc/include/asm/fadump.h
>> +++ b/arch/powerpc/include/asm/fadump.h
>> @@ -19,6 +19,7 @@ extern int is_fadump_active(void);
>>   extern int should_fadump_crash(void);
>>   extern void crash_fadump(struct pt_regs *, const char *);
>>   extern void fadump_cleanup(void);
>> +void fadump_setup_param_area(void);
>>   extern void fadump_append_bootargs(void);
>>
>>   #else    /* CONFIG_FA_DUMP */
>> @@ -26,6 +27,7 @@ static inline int is_fadump_active(void) { return 0; }
>>   static inline int should_fadump_crash(void) { return 0; }
>>   static inline void crash_fadump(struct pt_regs *regs, const char 
>> *str) { }
>>   static inline void fadump_cleanup(void) { }
>> +static inline void fadump_setup_param_area(void) { }
>>   static inline void fadump_append_bootargs(void) { }
>>   #endif /* !CONFIG_FA_DUMP */
>>
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index a612e7513a4f..3a2863307863 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -1586,6 +1586,12 @@ static void __init fadump_init_files(void)
>>           return;
>>       }
>>
>> +    if (fw_dump.param_area) {
>> +        rc = sysfs_create_file(fadump_kobj, 
>> &bootargs_append_attr.attr);
>> +        if (rc)
>> +            pr_err("unable to create bootargs_append sysfs file 
>> (%d)\n", rc);
>> +    }
>> +
>>       debugfs_create_file("fadump_region", 0444, arch_debugfs_dir, NULL,
>>                   &fadump_region_fops);
>>
>> @@ -1740,7 +1746,7 @@ static void __init fadump_process(void)
>>    * Reserve memory to store additional parameters to be passed
>>    * for fadump/capture kernel.
>>    */
>> -static void __init fadump_setup_param_area(void)
>> +void __init fadump_setup_param_area(void)
>>   {
>>       phys_addr_t range_start, range_end;
>>
>> @@ -1748,7 +1754,7 @@ static void __init fadump_setup_param_area(void)
>>           return;
>>
>>       /* This memory can't be used by PFW or bootloader as it is 
>> shared across kernels */
>> -    if (radix_enabled()) {
>> +    if (early_radix_enabled()) {
>>           /*
>>            * Anywhere in the upper half should be good enough as all 
>> memory
>>            * is accessible in real mode.
>> @@ -1776,12 +1782,12 @@ static void __init fadump_setup_param_area(void)
>>                                  COMMAND_LINE_SIZE,
>>                                  range_start,
>>                                  range_end);
>> -    if (!fw_dump.param_area || sysfs_create_file(fadump_kobj, 
>> &bootargs_append_attr.attr)) {
>> +    if (!fw_dump.param_area) {
>>           pr_warn("WARNING: Could not setup area to pass additional 
>> parameters!\n");
>>           return;
>>       }
>>
>> -    memset(phys_to_virt(fw_dump.param_area), 0, COMMAND_LINE_SIZE);
>> +    memset((void *)fw_dump.param_area, 0, COMMAND_LINE_SIZE);
>>   }
>>
>>   /*
>> @@ -1807,7 +1813,6 @@ int __init setup_fadump(void)
>>       }
>>       /* Initialize the kernel dump memory structure and register 
>> with f/w */
>>       else if (fw_dump.reserve_dump_area_size) {
>> -        fadump_setup_param_area();
>>           fw_dump.ops->fadump_init_mem_struct(&fw_dump);
>>           register_fadump();
>>       }
>> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
>> index 0be07ed407c7..47db1b1aef25 100644
>> --- a/arch/powerpc/kernel/prom.c
>> +++ b/arch/powerpc/kernel/prom.c
>> @@ -908,6 +908,9 @@ void __init early_init_devtree(void *params)
>>
>>       mmu_early_init_devtree();
>>
>> +    /* Setup param area for passing additional parameters to fadump 
>> capture kernel. */
>> +    fadump_setup_param_area();
>> +
>>   #ifdef CONFIG_PPC_POWERNV
>>       /* Scan and build the list of machine check recoverable ranges */
>>       of_scan_flat_dt(early_init_dt_scan_recoverable_ranges, NULL);