1. 08 Sep, 2014 1 commit
    • Arun Chandran's avatar
      arm64: convert part of soft_restart() to assembly · 5e051531
      Arun Chandran authored
      
      
      The current soft_restart() and setup_restart implementations incorrectly
      assume that compiler will not spill/fill values to/from stack. However
      this assumption seems to be wrong, revealed by the disassembly of the
      currently existing code (v3.16) built with Linaro GCC 4.9-2014.05.
      
      ffffffc000085224 <soft_restart>:
      ffffffc000085224:  a9be7bfd  stp    x29, x30, [sp,#-32]!
      ffffffc000085228:  910003fd  mov    x29, sp
      ffffffc00008522c:  f9000fa0  str    x0, [x29,#24]
      ffffffc000085230:  94003d21  bl     ffffffc0000946b4 <setup_mm_for_reboot>
      ffffffc000085234:  94003b33  bl     ffffffc000093f00 <flush_cache_all>
      ffffffc000085238:  94003dfa  bl     ffffffc000094a20 <cpu_cache_off>
      ffffffc00008523c:  94003b31  bl     ffffffc000093f00 <flush_cache_all>
      ffffffc000085240:  b0003321  adrp   x1, ffffffc0006ea000 <reset_devices>
      
      ffffffc000085244:  f9400fa0  ldr    x0, [x29,#24] ----> spilled addr
      ffffffc000085248:  f942fc22  ldr    x2, [x1,#1528] ----> global memstart_addr
      
      ffffffc00008524c:  f0000061  adrp   x1, ffffffc000094000 <__inval_cache_range+0x40>
      ffffffc000085250:  91290021  add    x1, x1, #0xa40
      ffffffc000085254:  8b010041  add    x1, x2, x1
      ffffffc000085258:  d2c00802  mov    x2, #0x4000000000           // #274877906944
      ffffffc00008525c:  8b020021  add    x1, x1, x2
      ffffffc000085260:  d63f0020  blr    x1
      ...
      
      Here the compiler generates memory accesses after the cache is disabled,
      loading stale values for the spilled value and global variable. As we cannot
      control when the compiler will access memory we must rewrite the
      functions in assembly to stash values we need in registers prior to
      disabling the cache, avoiding the use of memory.
      Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
      Signed-off-by: default avatarArun Chandran <achandran@mvista.com>
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      5e051531
  2. 16 Dec, 2013 1 commit
    • Lorenzo Pieralisi's avatar
      arm64: kernel: suspend/resume registers save/restore · 6732bc65
      Lorenzo Pieralisi authored
      
      
      Power management software requires the kernel to save and restore
      CPU registers while going through suspend and resume operations
      triggered by kernel subsystems like CPU idle and suspend to RAM.
      
      This patch implements code that provides save and restore mechanism
      for the arm v8 implementation. Memory for the context is passed as
      parameter to both cpu_do_suspend and cpu_do_resume functions, and allows
      the callers to implement context allocation as they deem fit.
      
      The registers that are saved and restored correspond to the registers set
      actually required by the kernel to be up and running which represents a
      subset of v8 ISA.
      Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
      6732bc65
  3. 17 Sep, 2012 1 commit