Re: [PATCH] Partially revert "MIPS: Remove old core dump functions"

[Marcin Nowakowski <marcin.nowakowski@imgtec.com>]

Hi Corey,

On 20.06.2017 22:39, minyard@acm.org wrote:
> From: Corey Minyard <cminyard@mvista.com>
> 
> This reverts part of commit 30852ad0039b4a54b5062efd66877125e519dc30,
> which removed some ELF coredump functions from MIPS.  They are no
> longer needed for normal coredumps, but they are still needed for
> kdump.  The kernel crashes when doing a kdump shutdown because
> elf_core_copy_kernel_regs() needs a MIPS-specific version and the
> reverted commit removes it.
> 
> This change adds back in ELF_CORE_COPY_REGS() and the required
> support for it.


A similar fix has been merged some time ago already:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=39a3cb27c123df8e8461291cc9e86f1ac3f0ea06

Marcin


> Signed-off-by: Corey Minyard <cminyard@mvista.com>
> ---
>   arch/mips/include/asm/elf.h |  7 +++++++
>   arch/mips/kernel/process.c  | 22 ++++++++++++++++++++++
>   2 files changed, 29 insertions(+)
> 
> diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
> index 2b3dc29..600db7b 100644
> --- a/arch/mips/include/asm/elf.h
> +++ b/arch/mips/include/asm/elf.h
> @@ -414,6 +414,13 @@ do {									\
>   
>   #endif /* CONFIG_64BIT */
>   
> +struct pt_regs;
> +
> +extern void elf_dump_regs(elf_greg_t *, struct pt_regs *regs);
> +
> +#define ELF_CORE_COPY_REGS(elf_regs, regs)                     \
> +       elf_dump_regs((elf_greg_t *)&(elf_regs), regs);
> +
>   #define CORE_DUMP_USE_REGSET
>   #define ELF_EXEC_PAGESIZE	PAGE_SIZE
>   
> diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
> index fbbf5fc..0d63aa1 100644
> --- a/arch/mips/kernel/process.c
> +++ b/arch/mips/kernel/process.c
> @@ -180,6 +180,28 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
>   	return 0;
>   }
>   
> +void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
> +{
> +	int i;
> +
> +	for (i = 0; i < EF_R0; i++)
> +		gp[i] = 0;
> +	gp[EF_R0] = 0;
> +	for (i = 1; i <= 31; i++)
> +		gp[EF_R0 + i] = regs->regs[i];
> +	gp[EF_R26] = 0;
> +	gp[EF_R27] = 0;
> +	gp[EF_LO] = regs->lo;
> +	gp[EF_HI] = regs->hi;
> +	gp[EF_CP0_EPC] = regs->cp0_epc;
> +	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
> +	gp[EF_CP0_STATUS] = regs->cp0_status;
> +	gp[EF_CP0_CAUSE] = regs->cp0_cause;
> +#ifdef EF_UNUSED0
> +	gp[EF_UNUSED0] = 0;
> +#endif
> +}
> +
>   #ifdef CONFIG_CC_STACKPROTECTOR
>   #include <linux/stackprotector.h>
>   unsigned long __stack_chk_guard __read_mostly;
>