^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) ======
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) Ptrace
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) ======
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) GDB intends to support the following hardware debug features of BookE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) processors:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) 4 hardware breakpoints (IAC)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) 2 hardware watchpoints (read, write and read-write) (DAC)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) 2 value conditions for the hardware watchpoints (DVC)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) For that, we need to extend ptrace so that GDB can query and set these
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) resources. Since we're extending, we're trying to create an interface
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) that's extendable and that covers both BookE and server processors, so
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) that GDB doesn't need to special-case each of them. We added the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) following 3 new ptrace requests.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 1. PTRACE_PPC_GETHWDEBUGINFO
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) ============================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) Query for GDB to discover the hardware debug features. The main info to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) be returned here is the minimum alignment for the hardware watchpoints.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) BookE processors don't have restrictions here, but server processors have
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) an 8-byte alignment restriction for hardware watchpoints. We'd like to avoid
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) adding special cases to GDB based on what it sees in AUXV.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) Since we're at it, we added other useful info that the kernel can return to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) GDB: this query will return the number of hardware breakpoints, hardware
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) watchpoints and whether it supports a range of addresses and a condition.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) The query will fill the following structure provided by the requesting process::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) struct ppc_debug_info {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) unit32_t version;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) unit32_t num_instruction_bps;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) unit32_t num_data_bps;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) unit32_t num_condition_regs;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) unit32_t data_bp_alignment;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) unit32_t sizeof_condition; /* size of the DVC register */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) uint64_t features; /* bitmask of the individual flags */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) features will have bits indicating whether there is support for::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) #define PPC_DEBUG_FEATURE_INSN_BP_RANGE 0x1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) #define PPC_DEBUG_FEATURE_INSN_BP_MASK 0x2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) #define PPC_DEBUG_FEATURE_DATA_BP_RANGE 0x4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) #define PPC_DEBUG_FEATURE_DATA_BP_MASK 0x8
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) #define PPC_DEBUG_FEATURE_DATA_BP_DAWR 0x10
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) #define PPC_DEBUG_FEATURE_DATA_BP_ARCH_31 0x20
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 2. PTRACE_SETHWDEBUG
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) Sets a hardware breakpoint or watchpoint, according to the provided structure::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) struct ppc_hw_breakpoint {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) uint32_t version;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) #define PPC_BREAKPOINT_TRIGGER_EXECUTE 0x1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) #define PPC_BREAKPOINT_TRIGGER_READ 0x2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) #define PPC_BREAKPOINT_TRIGGER_WRITE 0x4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) uint32_t trigger_type; /* only some combinations allowed */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) #define PPC_BREAKPOINT_MODE_EXACT 0x0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) #define PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE 0x1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) #define PPC_BREAKPOINT_MODE_RANGE_EXCLUSIVE 0x2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) #define PPC_BREAKPOINT_MODE_MASK 0x3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) uint32_t addr_mode; /* address match mode */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) #define PPC_BREAKPOINT_CONDITION_MODE 0x3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) #define PPC_BREAKPOINT_CONDITION_NONE 0x0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) #define PPC_BREAKPOINT_CONDITION_AND 0x1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) #define PPC_BREAKPOINT_CONDITION_EXACT 0x1 /* different name for the same thing as above */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) #define PPC_BREAKPOINT_CONDITION_OR 0x2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) #define PPC_BREAKPOINT_CONDITION_AND_OR 0x3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) #define PPC_BREAKPOINT_CONDITION_BE_ALL 0x00ff0000 /* byte enable bits */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) #define PPC_BREAKPOINT_CONDITION_BE(n) (1<<((n)+16))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) uint32_t condition_mode; /* break/watchpoint condition flags */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) uint64_t addr;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) uint64_t addr2;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) uint64_t condition_value;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) A request specifies one event, not necessarily just one register to be set.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) For instance, if the request is for a watchpoint with a condition, both the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) DAC and DVC registers will be set in the same request.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) With this GDB can ask for all kinds of hardware breakpoints and watchpoints
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) that the BookE supports. COMEFROM breakpoints available in server processors
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) are not contemplated, but that is out of the scope of this work.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) ptrace will return an integer (handle) uniquely identifying the breakpoint or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) watchpoint just created. This integer will be used in the PTRACE_DELHWDEBUG
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92) request to ask for its removal. Return -ENOSPC if the requested breakpoint
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) can't be allocated on the registers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) Some examples of using the structure to:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) - set a breakpoint in the first breakpoint register::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) p.version = PPC_DEBUG_CURRENT_VERSION;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) p.trigger_type = PPC_BREAKPOINT_TRIGGER_EXECUTE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) p.addr_mode = PPC_BREAKPOINT_MODE_EXACT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) p.addr = (uint64_t) address;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) p.addr2 = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) p.condition_value = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) - set a watchpoint which triggers on reads in the second watchpoint register::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) p.version = PPC_DEBUG_CURRENT_VERSION;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) p.trigger_type = PPC_BREAKPOINT_TRIGGER_READ;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) p.addr_mode = PPC_BREAKPOINT_MODE_EXACT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) p.addr = (uint64_t) address;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) p.addr2 = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) p.condition_value = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) - set a watchpoint which triggers only with a specific value::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) p.version = PPC_DEBUG_CURRENT_VERSION;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) p.trigger_type = PPC_BREAKPOINT_TRIGGER_READ;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) p.addr_mode = PPC_BREAKPOINT_MODE_EXACT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) p.condition_mode = PPC_BREAKPOINT_CONDITION_AND | PPC_BREAKPOINT_CONDITION_BE_ALL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) p.addr = (uint64_t) address;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) p.addr2 = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) p.condition_value = (uint64_t) condition;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) - set a ranged hardware breakpoint::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) p.version = PPC_DEBUG_CURRENT_VERSION;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) p.trigger_type = PPC_BREAKPOINT_TRIGGER_EXECUTE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) p.addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) p.addr = (uint64_t) begin_range;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) p.addr2 = (uint64_t) end_range;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) p.condition_value = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) - set a watchpoint in server processors (BookS)::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) p.version = 1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) p.trigger_type = PPC_BREAKPOINT_TRIGGER_RW;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) p.addr_mode = PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) p.addr_mode = PPC_BREAKPOINT_MODE_EXACT;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) p.condition_mode = PPC_BREAKPOINT_CONDITION_NONE;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) p.addr = (uint64_t) begin_range;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) /* For PPC_BREAKPOINT_MODE_RANGE_INCLUSIVE addr2 needs to be specified, where
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * addr2 - addr <= 8 Bytes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) p.addr2 = (uint64_t) end_range;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) p.condition_value = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 3. PTRACE_DELHWDEBUG
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) Takes an integer which identifies an existing breakpoint or watchpoint
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) (i.e., the value returned from PTRACE_SETHWDEBUG), and deletes the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) corresponding breakpoint or watchpoint..
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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