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From: Serge Semin <fancer.lancer@gmail.com>
To: Mike Rapoport <rppt@linux.ibm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paul.burton@mips.com>,
	James Hogan <jhogan@kernel.org>,
	Matt Redfearn <matt.redfearn@mips.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Bogendoerfer <tbogendoerfer@suse.de>,
	Huacai Chen <chenhc@lemote.com>, Stefan Agner <stefan@agner.ch>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Juergen Gross <jgross@suse.com>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/12] mips: Print the kernel virtual mem layout on debugging
Date: Wed, 24 Apr 2019 17:35:11 +0300
Message-ID: <20190424143510.ahzq2hpdje7iddzm@mobilestation> (raw)
In-Reply-To: <20190424134711.GE6278@rapoport-lnx>

On Wed, Apr 24, 2019 at 04:47:11PM +0300, Mike Rapoport wrote:
> On Wed, Apr 24, 2019 at 01:47:46AM +0300, Serge Semin wrote:
> > It is useful at least for debugging to have the kernel virtual
> > memory layout printed at boot time so to have the full information
> > about the booted kernel. Make the printing optional and available
> > only when DEBUG_KERNEL config is enabled so not to leak a sensitive
> > kernel information.
> > 
> > Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
> > ---
> >  arch/mips/mm/init.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 49 insertions(+)
> > 
> > diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
> > index bbb196ad5f26..c338bbd03b2a 100644
> > --- a/arch/mips/mm/init.c
> > +++ b/arch/mips/mm/init.c
> > @@ -31,6 +31,7 @@
> >  #include <linux/gfp.h>
> >  #include <linux/kcore.h>
> >  #include <linux/initrd.h>
> > +#include <linux/sizes.h>
> >  
> >  #include <asm/bootinfo.h>
> >  #include <asm/cachectl.h>
> > @@ -56,6 +57,53 @@ unsigned long empty_zero_page, zero_page_mask;
> >  EXPORT_SYMBOL_GPL(empty_zero_page);
> >  EXPORT_SYMBOL(zero_page_mask);
> >  
> > +/*
> > + * Print out the kernel virtual memory layout
> > + */
> > +#define MLK(b, t) (void *)b, (void *)t, ((t) - (b)) >> 10
> > +#define MLM(b, t) (void *)b, (void *)t, ((t) - (b)) >> 20
> > +#define MLK_ROUNDUP(b, t) (void *)b, (void *)t, DIV_ROUND_UP(((t) - (b)), SZ_1K)
> > +static void __init mem_print_kmap_info(void)
> > +{
> > +#ifdef CONFIG_DEBUG_KERNEL
> 
> Maybe CONFIG_DEBUG_VM?
> 

Last time I posted this patch Matt suggested to use CONFIG_DEBUG_KERNEL [1].
On the other hand arm platform prints this table unconditionally, but uses %lx
format for low-memory ranges and %p for kernel segments. I even more inclined
in the arm solution. But if selecting between DEBUG_KERNEL and DEBUG_VM I'd
stick with DEBUG_KERNEL, since VM-debug config help text states it is
intended for special performance checks: "Enable this to turn on extended
checks in the virtual-memory system that may impact performance," and
not for memory layout.

-Sergey

[1] https://lkml.org/lkml/2018/2/13/494

> > +	pr_notice("Kernel virtual memory layout:\n"
> > +		  "    lowmem  : 0x%px - 0x%px  (%4ld MB)\n"
> > +		  "      .text : 0x%px - 0x%px  (%4td kB)\n"
> > +		  "      .data : 0x%px - 0x%px  (%4td kB)\n"
> > +		  "      .init : 0x%px - 0x%px  (%4td kB)\n"
> > +		  "      .bss  : 0x%px - 0x%px  (%4td kB)\n"
> > +		  "    vmalloc : 0x%px - 0x%px  (%4ld MB)\n"
> > +#ifdef CONFIG_HIGHMEM
> > +		  "    pkmap   : 0x%px - 0x%px  (%4ld MB)\n"
> > +#endif
> > +		  "    fixmap  : 0x%px - 0x%px  (%4ld kB)\n",
> > +		  MLM(PAGE_OFFSET, (unsigned long)high_memory),
> > +		  MLK_ROUNDUP(_text, _etext),
> > +		  MLK_ROUNDUP(_sdata, _edata),
> > +		  MLK_ROUNDUP(__init_begin, __init_end),
> > +		  MLK_ROUNDUP(__bss_start, __bss_stop),
> > +		  MLM(VMALLOC_START, VMALLOC_END),
> > +#ifdef CONFIG_HIGHMEM
> > +		  MLM(PKMAP_BASE, (PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE)),
> > +#endif
> > +		  MLK(FIXADDR_START, FIXADDR_TOP));
> > +
> > +	/* Check some fundamental inconsistencies. May add something else? */
> > +#ifdef CONFIG_HIGHMEM
> > +	BUILD_BUG_ON(VMALLOC_END < PAGE_OFFSET);
> > +	BUG_ON(VMALLOC_END < (unsigned long)high_memory);
> > +	BUILD_BUG_ON((PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE) < PAGE_OFFSET);
> > +	BUG_ON((PKMAP_BASE) + (LAST_PKMAP)*(PAGE_SIZE) <
> > +		(unsigned long)high_memory);
> > +#endif
> > +	BUILD_BUG_ON(FIXADDR_TOP < PAGE_OFFSET);
> > +	BUG_ON(FIXADDR_TOP < (unsigned long)high_memory);
> > +#endif /* CONFIG_DEBUG_KERNEL */
> > +}
> > +#undef MLK
> > +#undef MLM
> > +#undef MLK_ROUNDUP
> > +
> >  /*
> >   * Not static inline because used by IP27 special magic initialization code
> >   */
> > @@ -479,6 +527,7 @@ void __init mem_init(void)
> >  	setup_zero_pages();	/* Setup zeroed pages.  */
> >  	mem_init_free_highmem();
> >  	mem_init_print_info(NULL);
> > +	mem_print_kmap_info();
> >  
> >  #ifdef CONFIG_64BIT
> >  	if ((unsigned long) &_text > (unsigned long) CKSEG0)
> > -- 
> > 2.21.0
> > 
> 
> -- 
> Sincerely yours,
> Mike.
> 

  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 22:47 [PATCH 00/12] mips: Post-bootmem-memblock transition fixes Serge Semin
2019-04-23 22:47 ` [PATCH 01/12] mips: Make sure kernel .bss exists in boot mem pool Serge Semin
2019-04-24 22:30   ` Paul Burton
2019-04-23 22:47 ` [PATCH 02/12] mips: Discard rudiments from bootmem_init Serge Semin
2019-04-24 22:30   ` Paul Burton
2019-04-23 22:47 ` [PATCH 03/12] mips: Combine memblock init and memory reservation loops Serge Semin
2019-04-24 22:30   ` Paul Burton
2019-04-23 22:47 ` [PATCH 04/12] mips: Reserve memory for the kernel image resources Serge Semin
2019-04-24 22:43   ` Paul Burton
2019-04-26  0:00     ` Serge Semin
2019-04-30 22:58       ` Paul Burton
2019-05-02 14:24         ` Serge Semin
2019-05-02 18:45           ` Paul Burton
2019-05-03 17:21             ` Serge Semin
2019-05-02 18:35   ` Paul Burton
2019-05-21 14:56   ` Geert Uytterhoeven
2019-05-21 15:53     ` Mike Rapoport
2019-05-21 16:39       ` Serge Semin
2019-05-22  7:50         ` Geert Uytterhoeven
2019-05-22  7:47       ` Geert Uytterhoeven
2019-05-22  8:08         ` Mike Rapoport
2019-05-22  8:14           ` Geert Uytterhoeven
2019-05-22 13:34             ` Serge Semin
2019-05-22 13:44               ` Geert Uytterhoeven
2019-05-22 13:54                 ` Serge Semin
2020-10-14  9:49                   ` Maciej W. Rozycki
2019-04-23 22:47 ` [PATCH 05/12] mips: Discard post-CMA-init foreach loop Serge Semin
2019-05-02 18:35   ` Paul Burton
2019-04-23 22:47 ` [PATCH 06/12] mips: Use memblock to reserve the __nosave memory range Serge Semin
2019-05-02 18:35   ` Paul Burton
2019-04-23 22:47 ` [PATCH 07/12] mips: Add reserve-nomap memory type support Serge Semin
2019-05-02 18:35   ` Paul Burton
2019-04-23 22:47 ` [PATCH 08/12] mips: Dump memblock regions for debugging Serge Semin
2019-04-24 13:45   ` Mike Rapoport
2019-04-24 14:20     ` Serge Semin
2019-04-23 22:47 ` [PATCH 09/12] mips: Perform early low memory test Serge Semin
2019-04-23 22:47 ` [PATCH 10/12] mips: Print the kernel virtual mem layout on debugging Serge Semin
2019-04-24 13:47   ` Mike Rapoport
2019-04-24 14:35     ` Serge Semin [this message]
2019-04-23 22:47 ` [PATCH 11/12] mips: Make sure dt memory regions are valid Serge Semin
2019-04-23 22:47 ` [PATCH 12/12] mips: Enable OF_RESERVED_MEM config Serge Semin
2019-04-24  6:17   ` Christoph Hellwig
2019-04-24  8:34     ` Serge Semin

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