lkml.org 
[lkml]   [2018]   [May]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH V2 03/20] x86: Add entry trampolines to kcore
From
Date
On 05/17/2018 02:21 AM, Adrian Hunter wrote:
> From: Alexander Shishkin <alexander.shishkin@linux.intel.com>
>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>

For the benefit of the poor souls looking at this code in the decades to
come, could you please take a few minutes to write a couple of sentences
about why this is being done?

> diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c
> index d1da5cf4b2de..fb1fbc8538fa 100644
> --- a/arch/x86/mm/cpu_entry_area.c
> +++ b/arch/x86/mm/cpu_entry_area.c
> @@ -3,6 +3,7 @@
> #include <linux/spinlock.h>
> #include <linux/percpu.h>
> #include <linux/kallsyms.h>
> +#include <linux/kcore.h>
>
> #include <asm/cpu_entry_area.h>
> #include <asm/pgtable.h>
> @@ -14,6 +15,7 @@
> #ifdef CONFIG_X86_64
> static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
> [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]);
> +static DEFINE_PER_CPU(struct kcore_list, kcore_entry_trampoline);
> #endif
>
> struct cpu_entry_area *get_cpu_entry_area(int cpu)
> @@ -147,6 +149,9 @@ static void __init setup_cpu_entry_area(int cpu)
>
> cea_set_pte(&get_cpu_entry_area(cpu)->entry_trampoline,
> __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX);
> + kclist_add(&per_cpu(kcore_entry_trampoline, cpu),
> + &get_cpu_entry_area(cpu)->entry_trampoline, PAGE_SIZE,
> + KCORE_TEXT);
> #endif

Any reason not to add a comment like:

/*
* The cpu_entry_area alias addresses are not in the kernel binary
* so they do not show up in /proc/kcore normally. This adds entries
* for them manually.
*/

\
 
 \ /
  Last update: 2018-05-17 19:53    [W:0.090 / U:5.228 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site