From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: changbin.du@gmail.com
Cc: Michal Marek <michal.lkml@markovi.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Russell King <linux@armlinux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>, X86 ML <x86@kernel.org>,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-sparse@vger.kernel.org, Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v2 1/4] x86/mm: surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif
Date: Sun, 28 Oct 2018 10:44:46 +0900 [thread overview]
Message-ID: <CAK7LNAQJxVDWU5GPY4O6x+z_Pkmh4KuHiTpkY_LDJwNYO-eCBw@mail.gmail.com> (raw)
In-Reply-To: <20181019124921.13780-2-changbin.du@gmail.com>
On Fri, Oct 19, 2018 at 9:50 PM Du Changbin <changbin.du@gmail.com> wrote:
>
> The level4_kernel_pgt is only defined when X86_5LEVEL is enabled. So
> surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif to
> make code correct.
For clarification, is it better to mention
that this is a preparation for CONFIG_CC_OPTIMIZE_FOR_DEBUGGING ?
> Signed-off-by: Du Changbin <changbin.du@gmail.com>
> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
> arch/x86/include/asm/pgtable_64.h | 2 ++
> arch/x86/kernel/head64.c | 13 ++++++-------
> 2 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
> index 9c85b54bf03c..9333f7fa5bdb 100644
> --- a/arch/x86/include/asm/pgtable_64.h
> +++ b/arch/x86/include/asm/pgtable_64.h
> @@ -16,7 +16,9 @@
> #include <linux/threads.h>
> #include <asm/fixmap.h>
>
> +#ifdef CONFIG_X86_5LEVEL
> extern p4d_t level4_kernel_pgt[512];
> +#endif
Is this #ifdef necessary?
It is harmless to declaring unused stuff.
> extern p4d_t level4_ident_pgt[512];
> extern pud_t level3_kernel_pgt[512];
> extern pud_t level3_ident_pgt[512];
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index ddee1f0870c4..4a59ef93c258 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -151,16 +151,15 @@ unsigned long __head __startup_64(unsigned long physaddr,
>
> pgd = fixup_pointer(&early_top_pgt, physaddr);
> p = pgd + pgd_index(__START_KERNEL_map);
> - if (la57)
> - *p = (unsigned long)level4_kernel_pgt;
> - else
> - *p = (unsigned long)level3_kernel_pgt;
> - *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
> -
> +#ifdef CONFIG_X86_5LEVEL
> if (la57) {
> + *p = (unsigned long)level4_kernel_pgt;
> p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
> p4d[511] += load_delta;
> - }
> + } else
> +#endif
> + *p = (unsigned long)level3_kernel_pgt;
> + *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
>
> pud = fixup_pointer(&level3_kernel_pgt, physaddr);
> pud[510] += load_delta;
> --
> 2.17.1
>
Hmm, this code looks a bit ugly...
Does the following one liner work with CONFIG_CC_OPTIMIZE_FOR_DEBUGGING ?
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 8047379..579847f 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -97,7 +97,7 @@ static bool __head check_la57_support(unsigned long physaddr)
return true;
}
#else
-static bool __head check_la57_support(unsigned long physaddr)
+static __always_inline bool __head check_la57_support(unsigned long physaddr)
{
return false;
}
--
Best Regards
Masahiro Yamada
next prev parent reply other threads:[~2018-10-28 1:45 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-19 12:49 [PATCH v2 0/4] kernel hacking: GCC optimization for better debug experience (-Og) Du Changbin
2018-10-19 12:49 ` [PATCH v2 1/4] x86/mm: surround level4_kernel_pgt with #ifdef CONFIG_X86_5LEVEL...#endif Du Changbin
2018-10-28 1:44 ` Masahiro Yamada [this message]
2018-10-28 12:46 ` Changbin Du
2018-10-19 12:49 ` [PATCH v2 2/4] kernel hacking: new config NO_AUTO_INLINE to disable compiler auto-inline optimizations Du Changbin
2018-10-28 13:11 ` Masahiro Yamada
2018-10-19 12:49 ` [PATCH v2 3/4] ARM: mm: fix build error in fix_to_virt with CONFIG_CC_OPTIMIZE_FOR_DEBUGGING Du Changbin
2018-10-19 12:49 ` [PATCH v2 4/4] kernel hacking: new config CC_OPTIMIZE_FOR_DEBUGGING to apply GCC -Og optimization Du Changbin
2018-10-28 2:28 ` Masahiro Yamada
2018-10-28 12:51 ` Changbin Du
2018-10-28 13:09 ` Masahiro Yamada
2018-10-28 13:14 ` Changbin Du
2018-10-29 13:01 ` Masahiro Yamada
2018-10-29 14:56 ` Changbin Du
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