1. 04 Nov, 2010 1 commit
    • Catalin Marinas's avatar
      ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs · 247055aa
      Catalin Marinas authored
      This patch removes the domain switching functionality via the set_fs and
      __switch_to functions on cores that have a TLS register.
      
      Currently, the ioremap and vmalloc areas share the same level 1 page
      tables and therefore have the same domain (DOMAIN_KERNEL). When the
      kernel domain is modified from Client to Manager (via the __set_fs or in
      the __switch_to function), the XN (eXecute Never) bit is overridden and
      newer CPUs can speculatively prefetch the ioremap'ed memory.
      
      Linux performs the kernel domain switching to allow user-specific
      functions (copy_to/from_user, get/put_user etc.) to access kernel
      memory. In order for these functions to work with the kernel domain set
      to Client, the patch modifies the LDRT/STRT and related instructions to
      the LDR/STR ones.
      
      The user pages access rights are also modified for kernel read-only
      access rather than read/write so that the copy-on-write mechanism still
      works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
      (CPU_32v6K is defined) since writing the TLS value to the high vectors page
      isn't possible.
      
      The user addresses passed to the kernel are checked by the access_ok()
      function so that they do not point to the kernel space.
      Tested-by: default avatarAnton Vorontsov <cbouatmailru@gmail.com>
      Cc: Tony Lindgren <tony@atomide.com>
      Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
      Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
      247055aa
  2. 03 Nov, 2010 6 commits
  3. 02 Nov, 2010 7 commits
  4. 01 Nov, 2010 19 commits
  5. 31 Oct, 2010 7 commits