arch/powerpc/kernel/hw_breakpoint_constraints.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 #include <linux/kernel.h>
   3 #include <linux/uaccess.h>
   4 #include <linux/sched.h>
   5 #include <asm/hw_breakpoint.h>
   6 #include <asm/sstep.h>
   7 #include <asm/cache.h>
   8
   9 static bool dar_in_user_range(unsigned long dar, struct arch_hw_breakpoint *info)
  10 {
  11         return ((info->address <= dar) && (dar - info->address < info->len));
  12 }
  13
  14 static bool ea_user_range_overlaps(unsigned long ea, int size,
  15                                    struct arch_hw_breakpoint *info)
  16 {
  17         return ((ea < info->address + info->len) &&
  18                 (ea + size > info->address));
  19 }
  20
  21 static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info)
  22 {
  23         unsigned long hw_start_addr, hw_end_addr;
  24
  25         hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
  26         hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
  27
  28         return ((hw_start_addr <= dar) && (hw_end_addr > dar));
  29 }
  30
  31 static bool ea_hw_range_overlaps(unsigned long ea, int size,
  32                                  struct arch_hw_breakpoint *info)
  33 {
  34         unsigned long hw_start_addr, hw_end_addr;
  35         unsigned long align_size = HW_BREAKPOINT_SIZE;
  36
  37         /*
  38          * On p10 predecessors, quadword is handle differently then
  39          * other instructions.
  40          */
  41         if (!cpu_has_feature(CPU_FTR_ARCH_31) && size == 16)
  42                 align_size = HW_BREAKPOINT_SIZE_QUADWORD;
  43
  44         hw_start_addr = ALIGN_DOWN(info->address, align_size);
  45         hw_end_addr = ALIGN(info->address + info->len, align_size);
  46
  47         return ((ea < hw_end_addr) && (ea + size > hw_start_addr));
  48 }
  49
  50 /*
  51  * If hw has multiple DAWR registers, we also need to check all
  52  * dawrx constraint bits to confirm this is _really_ a valid event.
  53  * If type is UNKNOWN, but privilege level matches, consider it as
  54  * a positive match.
  55  */
  56 static bool check_dawrx_constraints(struct pt_regs *regs, int type,
  57                                     struct arch_hw_breakpoint *info)
  58 {
  59         if (OP_IS_LOAD(type) && !(info->type & HW_BRK_TYPE_READ))
  60                 return false;
  61
  62         /*
  63          * The Cache Management instructions other than dcbz never
  64          * cause a match. i.e. if type is CACHEOP, the instruction
  65          * is dcbz, and dcbz is treated as Store.
  66          */
  67         if ((OP_IS_STORE(type) || type == CACHEOP) && !(info->type & HW_BRK_TYPE_WRITE))
  68                 return false;
  69
  70         if (is_kernel_addr(regs->nip) && !(info->type & HW_BRK_TYPE_KERNEL))
  71                 return false;
  72
  73         if (user_mode(regs) && !(info->type & HW_BRK_TYPE_USER))
  74                 return false;
  75
  76         return true;
  77 }
  78
  79 /*
  80  * Return true if the event is valid wrt dawr configuration,
  81  * including extraneous exception. Otherwise return false.
  82  */
  83 bool wp_check_constraints(struct pt_regs *regs, ppc_inst_t instr,
  84                           unsigned long ea, int type, int size,
  85                           struct arch_hw_breakpoint *info)
  86 {
  87         bool in_user_range = dar_in_user_range(regs->dar, info);
  88         bool dawrx_constraints;
  89
  90         /*
  91          * 8xx supports only one breakpoint and thus we can
  92          * unconditionally return true.
  93          */
  94         if (IS_ENABLED(CONFIG_PPC_8xx)) {
  95                 if (!in_user_range)
  96                         info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
  97                 return true;
  98         }
  99
 100         if (unlikely(ppc_inst_equal(instr, ppc_inst(0)))) {
 101                 if (cpu_has_feature(CPU_FTR_ARCH_31) &&
 102                     !dar_in_hw_range(regs->dar, info))
 103                         return false;
 104
 105                 return true;
 106         }
 107
 108         dawrx_constraints = check_dawrx_constraints(regs, type, info);
 109
 110         if (type == UNKNOWN) {
 111                 if (cpu_has_feature(CPU_FTR_ARCH_31) &&
 112                     !dar_in_hw_range(regs->dar, info))
 113                         return false;
 114
 115                 return dawrx_constraints;
 116         }
 117
 118         if (ea_user_range_overlaps(ea, size, info))
 119                 return dawrx_constraints;
 120
 121         if (ea_hw_range_overlaps(ea, size, info)) {
 122                 if (dawrx_constraints) {
 123                         info->type |= HW_BRK_TYPE_EXTRANEOUS_IRQ;
 124                         return true;
 125                 }
 126         }
 127         return false;
 128 }
 129
 130 void wp_get_instr_detail(struct pt_regs *regs, ppc_inst_t *instr,
 131                          int *type, int *size, unsigned long *ea)
 132 {
 133         struct instruction_op op;
 134         int err;
 135
 136         pagefault_disable();
 137         err = __get_user_instr(*instr, (void __user *)regs->nip);
 138         pagefault_enable();
 139
 140         if (err)
 141                 return;
 142
 143         analyse_instr(&op, regs, *instr);
 144         *type = GETTYPE(op.type);
 145         *ea = op.ea;
 146
 147         if (!(regs->msr & MSR_64BIT))
 148                 *ea &= 0xffffffffUL;
 149
 150
 151         *size = GETSIZE(op.type);
 152         if (*type == CACHEOP) {
 153                 *size = l1_dcache_bytes();
 154                 *ea &= ~(*size - 1);
 155         } else if (*type == LOAD_VMX || *type == STORE_VMX) {
 156                 *ea &= ~(*size - 1);
 157         }
 158 }