int aarch64_num_bp_regs;
int aarch64_num_wp_regs;
+/* True if this kernel does not have the bug described by PR
+ external/20207 (Linux >= 4.10). A fixed kernel supports any
+ contiguous range of bits in 8-bit byte DR_CONTROL_MASK. A buggy
+ kernel supports only 0x01, 0x03, 0x0f and 0xff. We start by
+ assuming the bug is fixed, and then detect the bug at
+ PTRACE_SETREGSET time. */
+static bool kernel_supports_any_contiguous_range = true;
+
+/* Return starting byte 0..7 incl. of a watchpoint encoded by CTRL. */
+
+unsigned int
+aarch64_watchpoint_offset (unsigned int ctrl)
+{
+ uint8_t mask = DR_CONTROL_MASK (ctrl);
+ unsigned retval;
+
+ /* Shift out bottom zeros. */
+ for (retval = 0; mask && (mask & 1) == 0; ++retval)
+ mask >>= 1;
+
+ return retval;
+}
+
/* Utility function that returns the length in bytes of a watchpoint
according to the content of a hardware debug control register CTRL.
- Note that the kernel currently only supports the following Byte
- Address Select (BAS) values: 0x1, 0x3, 0xf and 0xff, which means
- that for a hardware watchpoint, its valid length can only be 1
- byte, 2 bytes, 4 bytes or 8 bytes. */
+ Any contiguous range of bytes in CTRL is supported. The returned
+ value can be between 0..8 (inclusive). */
unsigned int
aarch64_watchpoint_length (unsigned int ctrl)
{
- switch (DR_CONTROL_LENGTH (ctrl))
- {
- case 0x01:
- return 1;
- case 0x03:
- return 2;
- case 0x0f:
- return 4;
- case 0xff:
- return 8;
- default:
- return 0;
- }
+ uint8_t mask = DR_CONTROL_MASK (ctrl);
+ unsigned retval;
+
+ /* Shift out bottom zeros. */
+ mask >>= aarch64_watchpoint_offset (ctrl);
+
+ /* Count bottom ones. */
+ for (retval = 0; (mask & 1) != 0; ++retval)
+ mask >>= 1;
+
+ if (mask != 0)
+ error (_("Unexpected hardware watchpoint length register value 0x%x"),
+ DR_CONTROL_MASK (ctrl));
+
+ return retval;
}
/* Given the hardware breakpoint or watchpoint type TYPE and its
breakpoint/watchpoint control register. */
static unsigned int
-aarch64_point_encode_ctrl_reg (enum target_hw_bp_type type, int len)
+aarch64_point_encode_ctrl_reg (enum target_hw_bp_type type, int offset, int len)
{
unsigned int ctrl, ttype;
+ gdb_assert (offset == 0 || kernel_supports_any_contiguous_range);
+ gdb_assert (offset + len <= AARCH64_HWP_MAX_LEN_PER_REG);
+
/* type */
switch (type)
{
ctrl = ttype << 3;
- /* length bitmask */
- ctrl |= ((1 << len) - 1) << 5;
+ /* offset and length bitmask */
+ ctrl |= ((1 << len) - 1) << (5 + offset);
/* enabled at el0 */
ctrl |= (2 << 1) | 1;
if (addr & (alignment - 1))
return 0;
- if (len != 8 && len != 4 && len != 2 && len != 1)
+ if ((!kernel_supports_any_contiguous_range
+ && len != 8 && len != 4 && len != 2 && len != 1)
+ || (kernel_supports_any_contiguous_range
+ && (len < 1 || len > 8)))
return 0;
return 1;
}
/* Given the (potentially unaligned) watchpoint address in ADDR and
- length in LEN, return the aligned address and aligned length in
- *ALIGNED_ADDR_P and *ALIGNED_LEN_P, respectively. The returned
- aligned address and length will be valid values to write to the
- hardware watchpoint value and control registers.
+ length in LEN, return the aligned address, offset from that base
+ address, and aligned length in *ALIGNED_ADDR_P, *ALIGNED_OFFSET_P
+ and *ALIGNED_LEN_P, respectively. The returned values will be
+ valid values to write to the hardware watchpoint value and control
+ registers.
The given watchpoint may get truncated if more than one hardware
register is needed to cover the watched region. *NEXT_ADDR_P
and *NEXT_LEN_P, if non-NULL, will return the address and length
of the remaining part of the watchpoint (which can be processed
- by calling this routine again to generate another aligned address
- and length pair.
+ by calling this routine again to generate another aligned address,
+ offset and length tuple.
Essentially, unaligned watchpoint is achieved by minimally
enlarging the watched area to meet the alignment requirement, and
if necessary, splitting the watchpoint over several hardware
- watchpoint registers. The trade-off is that there will be
- false-positive hits for the read-type or the access-type hardware
- watchpoints; for the write type, which is more commonly used, there
- will be no such issues, as the higher-level breakpoint management
- in gdb always examines the exact watched region for any content
- change, and transparently resumes a thread from a watchpoint trap
- if there is no change to the watched region.
+ watchpoint registers.
+
+ On kernels that predate the support for Byte Address Select (BAS)
+ in the hardware watchpoint control register, the offset from the
+ base address is always zero, and so in that case the trade-off is
+ that there will be false-positive hits for the read-type or the
+ access-type hardware watchpoints; for the write type, which is more
+ commonly used, there will be no such issues, as the higher-level
+ breakpoint management in gdb always examines the exact watched
+ region for any content change, and transparently resumes a thread
+ from a watchpoint trap if there is no change to the watched region.
Another limitation is that because the watched region is enlarged,
- the watchpoint fault address returned by
+ the watchpoint fault address discovered by
aarch64_stopped_data_address may be outside of the original watched
region, especially when the triggering instruction is accessing a
larger region. When the fault address is not within any known
range, watchpoints_triggered in gdb will get confused, as the
higher-level watchpoint management is only aware of original
watched regions, and will think that some unknown watchpoint has
- been triggered. In such a case, gdb may stop without displaying
- any detailed information.
-
- Once the kernel provides the full support for Byte Address Select
- (BAS) in the hardware watchpoint control register, these
- limitations can be largely relaxed with some further work. */
+ been triggered. To prevent such a case,
+ aarch64_stopped_data_address implementations in gdb and gdbserver
+ try to match the trapped address with a watched region, and return
+ an address within the latter. */
static void
aarch64_align_watchpoint (CORE_ADDR addr, int len, CORE_ADDR *aligned_addr_p,
- int *aligned_len_p, CORE_ADDR *next_addr_p,
- int *next_len_p)
+ int *aligned_offset_p, int *aligned_len_p,
+ CORE_ADDR *next_addr_p, int *next_len_p,
+ CORE_ADDR *next_addr_orig_p)
{
int aligned_len;
- unsigned int offset;
+ unsigned int offset, aligned_offset;
CORE_ADDR aligned_addr;
const unsigned int alignment = AARCH64_HWP_ALIGNMENT;
const unsigned int max_wp_len = AARCH64_HWP_MAX_LEN_PER_REG;
if (len <= 0)
return;
- /* Address to be put into the hardware watchpoint value register
- must be aligned. */
+ /* The address put into the hardware watchpoint value register must
+ be aligned. */
offset = addr & (alignment - 1);
aligned_addr = addr - offset;
+ aligned_offset
+ = kernel_supports_any_contiguous_range ? addr & (alignment - 1) : 0;
gdb_assert (offset >= 0 && offset < alignment);
gdb_assert (aligned_addr >= 0 && aligned_addr <= addr);
if (offset + len >= max_wp_len)
{
- /* Need more than one watchpoint registers; truncate it at the
+ /* Need more than one watchpoint register; truncate at the
alignment boundary. */
- aligned_len = max_wp_len;
+ aligned_len
+ = max_wp_len - (kernel_supports_any_contiguous_range ? offset : 0);
len -= (max_wp_len - offset);
addr += (max_wp_len - offset);
gdb_assert ((addr & (alignment - 1)) == 0);
aligned_len_array[AARCH64_HWP_MAX_LEN_PER_REG] =
{ 1, 2, 4, 4, 8, 8, 8, 8 };
- aligned_len = aligned_len_array[offset + len - 1];
+ aligned_len = (kernel_supports_any_contiguous_range
+ ? len : aligned_len_array[offset + len - 1]);
addr += len;
len = 0;
}
if (aligned_addr_p)
*aligned_addr_p = aligned_addr;
+ if (aligned_offset_p)
+ *aligned_offset_p = aligned_offset;
if (aligned_len_p)
*aligned_len_p = aligned_len;
if (next_addr_p)
*next_addr_p = addr;
if (next_len_p)
*next_len_p = len;
+ if (next_addr_orig_p)
+ *next_addr_orig_p = align_down (*next_addr_orig_p + alignment, alignment);
}
struct aarch64_dr_update_callback_param
iterate_over_lwps (pid_ptid, debug_reg_change_callback, (void *) ¶m);
}
+/* Reconfigure STATE to be compatible with Linux kernels with the PR
+ external/20207 bug. This is called when
+ KERNEL_SUPPORTS_ANY_CONTIGUOUS_RANGE transitions to false. Note we
+ don't try to support combining watchpoints with matching (and thus
+ shared) masks, as it's too late when we get here. On buggy
+ kernels, GDB will try to first setup the perfect matching ranges,
+ which will run out of registers before this function can merge
+ them. It doesn't look like worth the effort to improve that, given
+ eventually buggy kernels will be phased out. */
+
+static void
+aarch64_downgrade_regs (struct aarch64_debug_reg_state *state)
+{
+ for (int i = 0; i < aarch64_num_wp_regs; ++i)
+ if ((state->dr_ctrl_wp[i] & 1) != 0)
+ {
+ gdb_assert (state->dr_ref_count_wp[i] != 0);
+ uint8_t mask_orig = (state->dr_ctrl_wp[i] >> 5) & 0xff;
+ gdb_assert (mask_orig != 0);
+ static const uint8_t old_valid[] = { 0x01, 0x03, 0x0f, 0xff };
+ uint8_t mask = 0;
+ for (const uint8_t old_mask : old_valid)
+ if (mask_orig <= old_mask)
+ {
+ mask = old_mask;
+ break;
+ }
+ gdb_assert (mask != 0);
+
+ /* No update needed for this watchpoint? */
+ if (mask == mask_orig)
+ continue;
+ state->dr_ctrl_wp[i] |= mask << 5;
+ state->dr_addr_wp[i]
+ = align_down (state->dr_addr_wp[i], AARCH64_HWP_ALIGNMENT);
+
+ /* Try to match duplicate entries. */
+ for (int j = 0; j < i; ++j)
+ if ((state->dr_ctrl_wp[j] & 1) != 0
+ && state->dr_addr_wp[j] == state->dr_addr_wp[i]
+ && state->dr_addr_orig_wp[j] == state->dr_addr_orig_wp[i]
+ && state->dr_ctrl_wp[j] == state->dr_ctrl_wp[i])
+ {
+ state->dr_ref_count_wp[j] += state->dr_ref_count_wp[i];
+ state->dr_ref_count_wp[i] = 0;
+ state->dr_addr_wp[i] = 0;
+ state->dr_addr_orig_wp[i] = 0;
+ state->dr_ctrl_wp[i] &= ~1;
+ break;
+ }
+
+ aarch64_notify_debug_reg_change (state, 1 /* is_watchpoint */, i);
+ }
+}
+
/* Record the insertion of one breakpoint/watchpoint, as represented
by ADDR and CTRL, in the process' arch-specific data area *STATE. */
static int
aarch64_dr_state_insert_one_point (struct aarch64_debug_reg_state *state,
enum target_hw_bp_type type,
- CORE_ADDR addr, int len)
+ CORE_ADDR addr, int offset, int len,
+ CORE_ADDR addr_orig)
{
int i, idx, num_regs, is_watchpoint;
unsigned int ctrl, *dr_ctrl_p, *dr_ref_count;
- CORE_ADDR *dr_addr_p;
+ CORE_ADDR *dr_addr_p, *dr_addr_orig_p;
/* Set up state pointers. */
is_watchpoint = (type != hw_execute);
{
num_regs = aarch64_num_wp_regs;
dr_addr_p = state->dr_addr_wp;
+ dr_addr_orig_p = state->dr_addr_orig_wp;
dr_ctrl_p = state->dr_ctrl_wp;
dr_ref_count = state->dr_ref_count_wp;
}
{
num_regs = aarch64_num_bp_regs;
dr_addr_p = state->dr_addr_bp;
+ dr_addr_orig_p = nullptr;
dr_ctrl_p = state->dr_ctrl_bp;
dr_ref_count = state->dr_ref_count_bp;
}
- ctrl = aarch64_point_encode_ctrl_reg (type, len);
+ ctrl = aarch64_point_encode_ctrl_reg (type, offset, len);
/* Find an existing or free register in our cache. */
idx = -1;
idx = i;
/* no break; continue hunting for an exising one. */
}
- else if (dr_addr_p[i] == addr && dr_ctrl_p[i] == ctrl)
+ else if (dr_addr_p[i] == addr
+ && (dr_addr_orig_p == nullptr || dr_addr_orig_p[i] == addr_orig)
+ && dr_ctrl_p[i] == ctrl)
{
gdb_assert (dr_ref_count[i] != 0);
idx = i;
{
/* new entry */
dr_addr_p[idx] = addr;
+ if (dr_addr_orig_p != nullptr)
+ dr_addr_orig_p[idx] = addr_orig;
dr_ctrl_p[idx] = ctrl;
dr_ref_count[idx] = 1;
/* Notify the change. */
static int
aarch64_dr_state_remove_one_point (struct aarch64_debug_reg_state *state,
enum target_hw_bp_type type,
- CORE_ADDR addr, int len)
+ CORE_ADDR addr, int offset, int len,
+ CORE_ADDR addr_orig)
{
int i, num_regs, is_watchpoint;
unsigned int ctrl, *dr_ctrl_p, *dr_ref_count;
- CORE_ADDR *dr_addr_p;
+ CORE_ADDR *dr_addr_p, *dr_addr_orig_p;
/* Set up state pointers. */
is_watchpoint = (type != hw_execute);
{
num_regs = aarch64_num_wp_regs;
dr_addr_p = state->dr_addr_wp;
+ dr_addr_orig_p = state->dr_addr_orig_wp;
dr_ctrl_p = state->dr_ctrl_wp;
dr_ref_count = state->dr_ref_count_wp;
}
{
num_regs = aarch64_num_bp_regs;
dr_addr_p = state->dr_addr_bp;
+ dr_addr_orig_p = nullptr;
dr_ctrl_p = state->dr_ctrl_bp;
dr_ref_count = state->dr_ref_count_bp;
}
- ctrl = aarch64_point_encode_ctrl_reg (type, len);
+ ctrl = aarch64_point_encode_ctrl_reg (type, offset, len);
/* Find the entry that matches the ADDR and CTRL. */
for (i = 0; i < num_regs; ++i)
- if (dr_addr_p[i] == addr && dr_ctrl_p[i] == ctrl)
+ if (dr_addr_p[i] == addr
+ && (dr_addr_orig_p == nullptr || dr_addr_orig_p[i] == addr_orig)
+ && dr_ctrl_p[i] == ctrl)
{
gdb_assert (dr_ref_count[i] != 0);
break;
/* Clear the enable bit. */
ctrl &= ~1;
dr_addr_p[i] = 0;
+ if (dr_addr_orig_p != nullptr)
+ dr_addr_orig_p[i] = 0;
dr_ctrl_p[i] = ctrl;
/* Notify the change. */
aarch64_notify_debug_reg_change (state, is_watchpoint, i);
if (!aarch64_point_is_aligned (0 /* is_watchpoint */ , addr, len))
return -1;
- return aarch64_dr_state_insert_one_point (state, type, addr, len);
+ return aarch64_dr_state_insert_one_point (state, type, addr, 0, len, -1);
}
else
- return aarch64_dr_state_remove_one_point (state, type, addr, len);
+ return aarch64_dr_state_remove_one_point (state, type, addr, 0, len, -1);
}
/* This is essentially the same as aarch64_handle_breakpoint, apart
struct aarch64_debug_reg_state *state)
{
if (is_insert)
- return aarch64_dr_state_insert_one_point (state, type, addr, len);
+ return aarch64_dr_state_insert_one_point (state, type, addr, 0, len, addr);
else
- return aarch64_dr_state_remove_one_point (state, type, addr, len);
+ return aarch64_dr_state_remove_one_point (state, type, addr, 0, len, addr);
}
/* Insert/remove unaligned watchpoint by calling
CORE_ADDR addr, int len, int is_insert,
struct aarch64_debug_reg_state *state)
{
+ CORE_ADDR addr_orig = addr;
+
while (len > 0)
{
CORE_ADDR aligned_addr;
- int aligned_len, ret;
+ int aligned_offset, aligned_len, ret;
+ CORE_ADDR addr_orig_next = addr_orig;
- aarch64_align_watchpoint (addr, len, &aligned_addr, &aligned_len,
- &addr, &len);
+ aarch64_align_watchpoint (addr, len, &aligned_addr, &aligned_offset,
+ &aligned_len, &addr, &len, &addr_orig_next);
if (is_insert)
ret = aarch64_dr_state_insert_one_point (state, type, aligned_addr,
- aligned_len);
+ aligned_offset,
+ aligned_len, addr_orig);
else
ret = aarch64_dr_state_remove_one_point (state, type, aligned_addr,
- aligned_len);
+ aligned_offset,
+ aligned_len, addr_orig);
if (show_debug_regs)
debug_printf ("handle_unaligned_watchpoint: is_insert: %d\n"
" "
"aligned_addr: %s, aligned_len: %d\n"
" "
- "next_addr: %s, next_len: %d\n",
+ "addr_orig: %s\n"
+ " "
+ "next_addr: %s, next_len: %d\n"
+ " "
+ "addr_orig_next: %s\n",
is_insert, core_addr_to_string_nz (aligned_addr),
- aligned_len, core_addr_to_string_nz (addr), len);
+ aligned_len, core_addr_to_string_nz (addr_orig),
+ core_addr_to_string_nz (addr), len,
+ core_addr_to_string_nz (addr_orig_next));
+
+ addr_orig = addr_orig_next;
if (ret != 0)
return ret;
registers with data from *STATE. */
void
-aarch64_linux_set_debug_regs (const struct aarch64_debug_reg_state *state,
+aarch64_linux_set_debug_regs (struct aarch64_debug_reg_state *state,
int tid, int watchpoint)
{
int i, count;
if (ptrace (PTRACE_SETREGSET, tid,
watchpoint ? NT_ARM_HW_WATCH : NT_ARM_HW_BREAK,
(void *) &iov))
- error (_("Unexpected error setting hardware debug registers"));
+ {
+ /* Handle Linux kernels with the PR external/20207 bug. */
+ if (watchpoint && errno == EINVAL
+ && kernel_supports_any_contiguous_range)
+ {
+ kernel_supports_any_contiguous_range = false;
+ aarch64_downgrade_regs (state);
+ aarch64_linux_set_debug_regs (state, tid, watchpoint);
+ return;
+ }
+ error (_("Unexpected error setting hardware debug registers"));
+ }
}
/* Print the values of the cached breakpoint/watchpoint registers. */
debug_printf ("\tWATCHPOINTs:\n");
for (i = 0; i < aarch64_num_wp_regs; i++)
- debug_printf ("\tWP%d: addr=%s, ctrl=0x%08x, ref.count=%d\n",
+ debug_printf ("\tWP%d: addr=%s (orig=%s), ctrl=0x%08x, ref.count=%d\n",
i, core_addr_to_string_nz (state->dr_addr_wp[i]),
+ core_addr_to_string_nz (state->dr_addr_orig_wp[i]),
state->dr_ctrl_wp[i], state->dr_ref_count_wp[i]);
}
projects / deliverable / binutils-gdb.git / blobdiff