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SubjectRe: [PATCHv2] x86/boot/KASLR: skip the specified crashkernel reserved region
On 03/22/19 at 03:52pm, Baoquan He wrote:
> On 03/22/19 at 03:43pm, Pingfan Liu wrote:
> > > > +/* parse crashkernel=x@y option */
> > > > +static void mem_avoid_crashkernel_simple(char *option)
> > >
> > > Chao ever mentioned this, I want to ask again, why does it has to be
> > > xxx_simple()?
> > >
> > Seems that I had replied Chao's question in another email. The naming
> > follows the function parse_crashkernel_simple(), as the notes above
> ~~~~~~~~~~~~~~~~~~~~~~~~
>
> Sorry, I don't get. typo?

OK, I misunderstood it. We do have parse_crashkernel_simple() to handle
crashkernel=size[@offset] case, to differente with other complicated
cases, like crashkernel=size,[high|low],

Then I am fine with this naming. Soryy about the noise.

By the way, do you think if we should take care of this case:
crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]

It can also specify @offset. Not sure if it's too complicated, you may
have a investigation.

These two cases have dependency on your crashkernel=X bug fix patch.
The current code only allow crashkernel= to reserve under 896MB. I
noticed Boris has agreed on the solution. Maybe you can repost a new
version based on the discussion.

http://lkml.kernel.org/r/1548047768-7656-1-git-send-email-kernelfans@gmail.com
[PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr

Thanks
Baoquan

>
> > the definition
> > /*
> > * That function parses "simple" (old) crashkernel command lines like
> > *
> > * crashkernel=size[@offset]
>
> Hmm, should only crashkernel=size@offset be cared? crashkernel=size will
> auto finding a place to reserve, and that is after KASLR.
>
> > *
> > * It returns 0 on success and -EINVAL on failure.
> > */
> > static int __init parse_crashkernel_simple(char *cmdline,
> >
> > Do you have alternative suggestion?
> >
> > > Except of these, patch looks good to me. It's a nice catch, and only
> > > need a simple fix based on the current code.
> > >
> > Thank you for the kindly review.
> >
> > Regards,
> > Pingfan
> >
> > > Thanks
> > > Baoquan
> > >
> > > > +{
> > > > + unsigned long long crash_size, crash_base;
> > > > + char *cur = option;
> > > > +
> > > > + crash_size = memparse(option, &cur);
> > > > + if (option == cur)
> > > > + return;
> > > > +
> > > > + if (*cur == '@') {
> > > > + option = cur + 1;
> > > > + crash_base = memparse(option, &cur);
> > > > + if (option == cur)
> > > > + return;
> > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].start = crash_base;
> > > > + mem_avoid[MEM_AVOID_CRASHKERNEL].size = crash_size;
> > > > + }
> > > > +}
> > > >
> > > > static void handle_mem_options(void)
> > > > {
> > > > @@ -250,7 +270,7 @@ static void handle_mem_options(void)
> > > > u64 mem_size;
> > > >
> > > > if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
> > > > - !strstr(args, "hugepages"))
> > > > + !strstr(args, "hugepages") && !strstr(args, "crashkernel="))
> > > > return;
> > > >
> > > > tmp_cmdline = malloc(len + 1);
> > > > @@ -286,6 +306,8 @@ static void handle_mem_options(void)
> > > > goto out;
> > > >
> > > > mem_limit = mem_size;
> > > > + } else if (strstr(param, "crashkernel")) {
> > > > + mem_avoid_crashkernel_simple(val);
> > > > }
> > > > }
> > > >
> > > > @@ -414,7 +436,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
> > > >
> > > > /* We don't need to set a mapping for setup_data. */
> > > >
> > > > - /* Mark the memmap regions we need to avoid */
> > > > + /* Mark the regions we need to avoid */
> > > > handle_mem_options();
> > > >
> > > > #ifdef CONFIG_X86_VERBOSE_BOOTUP
> > > > --
> > > > 2.7.4
> > > >

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