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Re: [PATCH] MIPS: Make virt_to_phys() work for all unmapped addresses.

To: David Daney <ddaney.cavm@gmail.com>
Subject: Re: [PATCH] MIPS: Make virt_to_phys() work for all unmapped addresses.
From: David Daney <ddaney@caviumnetworks.com>
Date: Tue, 7 May 2013 10:58:19 -0700
Cc: <linux-mips@linux-mips.org>, <ralf@linux-mips.org>, Jiang Liu <liuj97@gmail.com>, <eunb.song@samsung.com>, <linux-kernel@vger.kernel.org>, David Daney <david.daney@cavium.com>
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It doesn't apply anymore.  It was against v3.4.

I will send one against Linus' tree soon.

David Daney


On 05/07/2013 10:23 AM, David Daney wrote:
From: David Daney <david.daney@cavium.com>

As reported:
   This problem was discovered when doing BGP traffic with the TCP MD5 option
   activated, where the following call chain caused a crash:

    * tcp_v4_rcv
    *  tcp_v4_timewait_ack
    *   tcp_v4_send_ack -> follow stack variable rep.th
    *    tcp_v4_md5_hash_hdr
    *     tcp_md5_hash_header
    *      sg_init_one
    *       sg_set_buf
    *        virt_to_page

   I noticed that tcp_v4_send_reset uses a similar stack variable and
   also calls tcp_v4_md5_hash_hdr, so it has the same problem.

The networking core can indirectly call virt_to_phys() on stack
addresses, if this is done from PID 0, the stack will usually be in
CKSEG0, so virt_to_phys() needs to work there as well

Signed-off-by: David Daney <david.daney@cavium.com>
---

Not tested against kernel.org kernel, but it may still apply

This could also fix problems noted by Eunbong Song with the
free_initmem_default() call.

  arch/mips/include/asm/io.h   | 2 +-
  arch/mips/include/asm/page.h | 5 +++--
  2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index a58f229..37fa957 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -116,7 +116,7 @@ static inline void set_io_port_base(unsigned long base)
   */
  static inline unsigned long virt_to_phys(volatile const void *address)
  {
-       return (unsigned long)address - PAGE_OFFSET + PHYS_OFFSET;
+       return __pa(address);
  }

  /*
diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index cee3893..e09bff9 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -48,7 +48,6 @@
  #ifndef __ASSEMBLY__

  #include <linux/pfn.h>
-#include <asm/io.h>

  extern void build_clear_page(void);
  extern void build_copy_page(void);
@@ -139,7 +138,6 @@ typedef struct { unsigned long pgprot; } pgprot_t;
   */
  #define ptep_buddy(x) ((pte_t *)((unsigned long)(x) ^ sizeof(pte_t)))

-#endif /* !__ASSEMBLY__ */

  /*
   * __pa()/__va() should be used only during mem init.
@@ -156,6 +154,9 @@ typedef struct { unsigned long pgprot; } pgprot_t;
  #endif
  #define __va(x)               ((void *)((unsigned long)(x) + PAGE_OFFSET - 
PHYS_OFFSET))

+#include <asm/io.h>
+#endif /* !__ASSEMBLY__ */
+
  /*
   * RELOC_HIDE was originally added by 6007b903dfe5f1d13e0c711ac2894bdd4a61b1ad
   * (lmo) rsp. 8431fd094d625b94d364fe393076ccef88e6ce18 (kernel.org).  The




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