• Paul Gortmaker's avatar
    powerpc: Fix smp_processor_id() in preemptible splat in set_breakpoint · 21f58507
    Paul Gortmaker authored
    Currently, on 8641D, which doesn't set CONFIG_HAVE_HW_BREAKPOINT
    we get the following splat:
    
    BUG: using smp_processor_id() in preemptible [00000000] code: login/1382
    caller is set_breakpoint+0x1c/0xa0
    CPU: 0 PID: 1382 Comm: login Not tainted 3.15.0-rc3-00041-g2aafe1a4 #1
    Call Trace:
    [decd5d80] [c0008dc4] show_stack+0x50/0x158 (unreliable)
    [decd5dc0] [c03c6fa0] dump_stack+0x7c/0xdc
    [decd5de0] [c01f8818] check_preemption_disabled+0xf4/0x104
    [decd5e00] [c00086b8] set_breakpoint+0x1c/0xa0
    [decd5e10] [c00d4530] flush_old_exec+0x2bc/0x588
    [decd5e40] [c011c468] load_elf_binary+0x2ac/0x1164
    [decd5ec0] [c00d35f8] search_binary_handler+0xc4/0x1f8
    [decd5ef0] [c00d4ee8] do_execve+0x3d8/0x4b8
    [decd5f40] [c001185c] ret_from_syscall+0x0/0x38
     --- Exception: c01 at 0xfeee554
        LR = 0xfeee7d4
    
    The call path in this case is:
    
    	flush_thread
    	   --> set_debug_reg_defaults
    	     --> set_breakpoint
    	       --> __get_cpu_var
    
    Since preemption is enabled in the cleanup of flush thread, and
    there is no need to disable it, introduce the distinction between
    set_breakpoint and __set_breakpoint, leaving only the flush_thread
    instance as the current user of set_breakpoint.
    Signed-off-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
    Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
    21f58507
process.c 43.2 KB