linux-kernel - Re: [PATCH v2 3/5] mips: Print the kernel virtual mem layout on debugging

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Message-ID: <20190506191419.w3qtkgcjrjjuzwmu@pburton-laptop>
Date:   Mon, 6 May 2019 19:14:21 +0000
From:   Paul Burton <paul.burton@...s.com>
To:     Serge Semin <fancer.lancer@...il.com>
CC:     Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <jhogan@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Bogendoerfer <tbogendoerfer@...e.de>,
        Huacai Chen <chenhc@...ote.com>,
        Stefan Agner <stefan@...er.ch>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Juergen Gross <jgross@...e.com>,
        Serge Semin <Sergey.Semin@...latforms.ru>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/5] mips: Print the kernel virtual mem layout on
 debugging

Hi Serge,

On Fri, May 03, 2019 at 08:50:39PM +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@...il.com>
> ---
>  arch/mips/mm/init.c | 49 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)

FYI the rest of the series is in mips-next, but I left this one out
because it gives me compile errors for 64r6el_defconfig:

In file included from ./include/linux/printk.h:7,
                 from ./include/linux/kernel.h:15,
                 from ./include/asm-generic/bug.h:18,
                 from ./arch/mips/include/asm/bug.h:42,
                 from ./include/linux/bug.h:5,
                 from arch/mips/mm/init.c:11:
arch/mips/mm/init.c: In function ‘mem_print_kmap_info’:
./include/linux/kern_levels.h:5:18: error: format ‘%ld’ expects argument of type ‘long int’, but argument 4 has type ‘long long unsigned int’ [-Werror=format=]
 #define KERN_SOH "\001"  /* ASCII Start Of Header */
                  ^~~~~~
./include/linux/kern_levels.h:13:21: note: in expansion of macro ‘KERN_SOH’
 #define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */
                     ^~~~~~~~
./include/linux/printk.h:307:9: note: in expansion of macro ‘KERN_NOTICE’
  printk(KERN_NOTICE pr_fmt(fmt), ##__VA_ARGS__)
         ^~~~~~~~~~~
arch/mips/mm/init.c:69:2: note: in expansion of macro ‘pr_notice’
  pr_notice("Kernel virtual memory layout:\n"
  ^~~~~~~~~
arch/mips/mm/init.c:70:39: note: format string is defined here
     "    lowmem  : 0x%px - 0x%px  (%4ld MB)\n"
                                    ~~~^
                                    %4lld
In file included from ./arch/mips/include/asm/bug.h:5,
                 from ./include/linux/bug.h:5,
                 from arch/mips/mm/init.c:11:
In function ‘mem_print_kmap_info’,
    inlined from ‘mem_init’ at arch/mips/mm/init.c:530:2:
./include/linux/compiler.h:344:38: error: call to ‘__compiletime_assert_99’ declared with attribute error: BUILD_BUG_ON failed: FIXADDR_TOP < PAGE_OFFSET
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
                                      ^
./include/linux/compiler.h:325:4: note: in definition of macro ‘__compiletime_assert’
    prefix ## suffix();    \
    ^~~~~~
./include/linux/compiler.h:344:2: note: in expansion of macro ‘_compiletime_assert’
  _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
  ^~~~~~~~~~~~~~~~~~~
./include/linux/build_bug.h:39:37: note: in expansion of macro ‘compiletime_assert’
 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                     ^~~~~~~~~~~~~~~~~~
./include/linux/build_bug.h:50:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
  BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
  ^~~~~~~~~~~~~~~~
arch/mips/mm/init.c:99:2: note: in expansion of macro ‘BUILD_BUG_ON’
  BUILD_BUG_ON(FIXADDR_TOP < PAGE_OFFSET);
  ^~~~~~~~~~~~
cc1: all warnings being treated as errors
make[3]: *** [scripts/Makefile.build:278: arch/mips/mm/init.o] Error 1
make[2]: *** [scripts/Makefile.build:489: arch/mips/mm] Error 2

Thanks,
    Paul