From 8d689ee570e7c4c61231b919d5b6a34c20414c43 Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Thu, 15 Oct 2015 15:05:10 +0100 Subject: [PATCH] aarch64 multi-arch part 6: HW breakpoint on unaligned address Nowadays, both aarch64 GDB and linux kernel assumes that address for setting breakpoint should be 4-byte aligned. However that is not true after we support multi-arch, because thumb instruction can be at 2-byte aligned address. Patch http://lists.infradead.org/pipermail/linux-arm-kernel/2015-October/375141.html to linux kernel is to teach kernel to handle 2-byte aligned address for HW breakpoint, while this patch is to teach aarch64 GDB handle 2-byte aligned address. First of all, we call gdbarch_breakpoint_from_pc to get the instruction length rather than using hard-coded 4. Secondly, in GDBserver, we set length back to 2 if it is 3, because GDB encode 3 in it to indicate it is a 32-bit thumb breakpoint. Then we relax the address alignment check from 4-byte aligned to 2-byte aligned. This patch enables some tests (such as gdb.base/break-idempotent.exp, gdb.base/cond-eval-mode.exp, gdb.base/watchpoint-reuse-slot.exp,) and fixes many fails (such as gdb.base/hbreak2.exp) when the program is compiled in thumb mode on aarch64. Regression tested on aarch64-linux, both native and gdbserver. This is the last patch of multi-arch work. gdb: 2015-10-15 Yao Qi * aarch64-linux-nat.c (aarch64_linux_insert_hw_breakpoint): Call gdbarch_breakpoint_from_pc to instruction length. (aarch64_linux_remove_hw_breakpoint): Likewise. * common/common-regcache.h (regcache_register_size): Declare. * nat/aarch64-linux-hw-point.c: Include "common-regcache.h". (aarch64_point_is_aligned): Set alignment to 2 for breakpoint if the process is 32bit, otherwise set alignment to 4. (aarch64_handle_breakpoint): Update comments. * regcache.c (regcache_register_size): New function. gdb/gdbserver: 2015-10-15 Yao Qi * linux-aarch64-low.c (aarch64_insert_point): Set len to 2 if it is 3. (aarch64_remove_point): Likewise. * regcache.c (regcache_register_size): New function. --- gdb/ChangeLog | 12 ++++++++++++ gdb/aarch64-linux-nat.c | 8 ++++++-- gdb/common/common-regcache.h | 5 +++++ gdb/gdbserver/ChangeLog | 7 +++++++ gdb/gdbserver/linux-aarch64-low.c | 28 ++++++++++++++++++++++------ gdb/gdbserver/regcache.c | 8 ++++++++ gdb/nat/aarch64-linux-hw-point.c | 22 +++++++++++++++++++--- gdb/regcache.c | 8 ++++++++ 8 files changed, 87 insertions(+), 11 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9fe691a5a2..8646e6dadf 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,15 @@ +2015-10-15 Yao Qi + + * aarch64-linux-nat.c (aarch64_linux_insert_hw_breakpoint): + Call gdbarch_breakpoint_from_pc to instruction length. + (aarch64_linux_remove_hw_breakpoint): Likewise. + * common/common-regcache.h (regcache_register_size): Declare. + * nat/aarch64-linux-hw-point.c: Include "common-regcache.h". + (aarch64_point_is_aligned): Set alignment to 2 for breakpoint if + the process is 32bit, otherwise set alignment to 4. + (aarch64_handle_breakpoint): Update comments. + * regcache.c (regcache_register_size): New function. + 2015-10-15 Aleksandar Ristovski * gdbarch.sh (core_regset_section): Remove. diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c index c9f439f75e..4d3d55aab9 100644 --- a/gdb/aarch64-linux-nat.c +++ b/gdb/aarch64-linux-nat.c @@ -608,11 +608,13 @@ aarch64_linux_insert_hw_breakpoint (struct target_ops *self, { int ret; CORE_ADDR addr = bp_tgt->placed_address = bp_tgt->reqstd_address; - const int len = 4; + int len; const enum target_hw_bp_type type = hw_execute; struct aarch64_debug_reg_state *state = aarch64_get_debug_reg_state (ptid_get_pid (inferior_ptid)); + gdbarch_breakpoint_from_pc (gdbarch, &addr, &len); + if (show_debug_regs) fprintf_unfiltered (gdb_stdlog, @@ -640,11 +642,13 @@ aarch64_linux_remove_hw_breakpoint (struct target_ops *self, { int ret; CORE_ADDR addr = bp_tgt->placed_address; - const int len = 4; + int len = 4; const enum target_hw_bp_type type = hw_execute; struct aarch64_debug_reg_state *state = aarch64_get_debug_reg_state (ptid_get_pid (inferior_ptid)); + gdbarch_breakpoint_from_pc (gdbarch, &addr, &len); + if (show_debug_regs) fprintf_unfiltered (gdb_stdlog, "remove_hw_breakpoint on entry (addr=0x%08lx, len=%d))\n", diff --git a/gdb/common/common-regcache.h b/gdb/common/common-regcache.h index a922316180..c47060374a 100644 --- a/gdb/common/common-regcache.h +++ b/gdb/common/common-regcache.h @@ -28,6 +28,11 @@ extern struct regcache *get_thread_regcache_for_ptid (ptid_t ptid); +/* Return the size of register numbered N in REGCACHE. This function + must be provided by the client. */ + +extern int regcache_register_size (const struct regcache *regcache, int n); + /* Read the PC register. This function must be provided by the client. */ diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 8308d0713e..3adbff6d69 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,10 @@ +2015-10-15 Yao Qi + + * linux-aarch64-low.c (aarch64_insert_point): Set len to 2 + if it is 3. + (aarch64_remove_point): Likewise. + * regcache.c (regcache_register_size): New function. + 2015-10-12 Yao Qi * linux-aarch64-low.c: Update all callers as emit_load_store diff --git a/gdb/gdbserver/linux-aarch64-low.c b/gdb/gdbserver/linux-aarch64-low.c index 9cefdda214..780c5e3f65 100644 --- a/gdb/gdbserver/linux-aarch64-low.c +++ b/gdb/gdbserver/linux-aarch64-low.c @@ -315,9 +315,17 @@ aarch64_insert_point (enum raw_bkpt_type type, CORE_ADDR addr, ret = -1; } else - ret = - aarch64_handle_breakpoint (targ_type, addr, len, 1 /* is_insert */, - state); + { + if (len == 3) + { + /* LEN is 3 means the breakpoint is set on a 32-bit thumb + instruction. Set it to 2 to correctly encode length bit + mask in hardware/watchpoint control register. */ + len = 2; + } + ret = aarch64_handle_breakpoint (targ_type, addr, len, + 1 /* is_insert */, state); + } if (show_debug_regs) aarch64_show_debug_reg_state (state, "insert_point", addr, len, @@ -353,9 +361,17 @@ aarch64_remove_point (enum raw_bkpt_type type, CORE_ADDR addr, aarch64_handle_watchpoint (targ_type, addr, len, 0 /* is_insert */, state); else - ret = - aarch64_handle_breakpoint (targ_type, addr, len, 0 /* is_insert */, - state); + { + if (len == 3) + { + /* LEN is 3 means the breakpoint is set on a 32-bit thumb + instruction. Set it to 2 to correctly encode length bit + mask in hardware/watchpoint control register. */ + len = 2; + } + ret = aarch64_handle_breakpoint (targ_type, addr, len, + 0 /* is_insert */, state); + } if (show_debug_regs) aarch64_show_debug_reg_state (state, "remove_point", addr, len, diff --git a/gdb/gdbserver/regcache.c b/gdb/gdbserver/regcache.c index f79063c499..e11b17332f 100644 --- a/gdb/gdbserver/regcache.c +++ b/gdb/gdbserver/regcache.c @@ -316,6 +316,14 @@ register_size (const struct target_desc *tdesc, int n) return tdesc->reg_defs[n].size / 8; } +/* See common/common-regcache.h. */ + +int +regcache_register_size (const struct regcache *regcache, int n) +{ + return register_size (regcache->tdesc, n); +} + static unsigned char * register_data (struct regcache *regcache, int n, int fetch) { diff --git a/gdb/nat/aarch64-linux-hw-point.c b/gdb/nat/aarch64-linux-hw-point.c index bca6ec1ce7..1a5fa6ac2a 100644 --- a/gdb/nat/aarch64-linux-hw-point.c +++ b/gdb/nat/aarch64-linux-hw-point.c @@ -18,6 +18,7 @@ #include "common-defs.h" #include "break-common.h" +#include "common-regcache.h" #include "nat/linux-nat.h" #include "aarch64-linux-hw-point.h" @@ -112,8 +113,23 @@ aarch64_point_encode_ctrl_reg (enum target_hw_bp_type type, int len) static int aarch64_point_is_aligned (int is_watchpoint, CORE_ADDR addr, int len) { - unsigned int alignment = is_watchpoint ? AARCH64_HWP_ALIGNMENT - : AARCH64_HBP_ALIGNMENT; + unsigned int alignment = 0; + + if (is_watchpoint) + alignment = AARCH64_HWP_ALIGNMENT; + else + { + struct regcache *regcache + = get_thread_regcache_for_ptid (current_lwp_ptid ()); + + /* Set alignment to 2 only if the current process is 32-bit, + since thumb instruction can be 2-byte aligned. Otherwise, set + alignment to AARCH64_HBP_ALIGNMENT. */ + if (regcache_register_size (regcache, 0) == 8) + alignment = AARCH64_HBP_ALIGNMENT; + else + alignment = 2; + } if (addr & (alignment - 1)) return 0; @@ -445,7 +461,7 @@ aarch64_handle_breakpoint (enum target_hw_bp_type type, CORE_ADDR addr, struct aarch64_debug_reg_state *state) { /* The hardware breakpoint on AArch64 should always be 4-byte - aligned. */ + aligned, but on AArch32, it can be 2-byte aligned. */ if (!aarch64_point_is_aligned (0 /* is_watchpoint */ , addr, len)) return -1; diff --git a/gdb/regcache.c b/gdb/regcache.c index 74d883aa59..5ee31fb20d 100644 --- a/gdb/regcache.c +++ b/gdb/regcache.c @@ -179,6 +179,14 @@ register_size (struct gdbarch *gdbarch, int regnum) return size; } +/* See common/common-regcache.h. */ + +int +regcache_register_size (const struct regcache *regcache, int n) +{ + return register_size (get_regcache_arch (regcache), n); +} + /* The register cache for storing raw register values. */ struct regcache -- 2.34.1