This change:
commit b775012e84
Author: Luis Machado <luisgpm@br.ibm.com>
Date: Fri Feb 24 15:10:59 2012 +0000
2012-02-24 Luis Machado <lgustavo@codesourcery.com>
* remote.c (remote_supports_cond_breakpoints): New forward
declaration.
[...]
changed the way breakpoints are inserted and removed such that
`insert_bp_location' can now be called with the breakpoint being handled
already in place, while previously the call was only ever made for
breakpoints that have not been put in place. This in turn caused an
issue for software breakpoints and targets for which a breakpoint's
`placed_address' may not be the same as the original requested address.
The issue is `insert_bp_location' overwrites the previously adjusted
value in `placed_address' with the original address, that is only
replaced back with the correct adjusted address later on when
`gdbarch_breakpoint_from_pc' is called. Meanwhile there's a window
where the value in `placed_address' does not correspond to data stored
in `shadow_contents', leading to incorrect instruction bytes being
supplied when `one_breakpoint_xfer_memory' is called to supply the
instruction overlaid by the breakpoint.
And this is exactly what happens on the MIPS target with software
breakpoints placed in microMIPS code. In this case not only
`placed_address' is not the original address because of the ISA bit, but
`mips_breakpoint_from_pc' has to read the original instruction to
determine which one of the two software breakpoint instruction encodings
to choose as well. The 16-bit encoding is used to replace 16-bit
instructions and similarly the 32-bit one is used with 32-bit
instructions, to satisfy branch delay slot size requirements.
The mismatch between `placed_address' and the address data in
`shadow_contents' has been obtained from leads to the wrong encoding
being used in some cases, which in the case of a 32-bit software
breakpoint instruction replacing a 16-bit instruction causes corruption
to the adjacent following instruction and leads the debug session astray
if execution reaches there e.g. with a jump.
To address this problem I made the change below, that adds a
`reqstd_address' field to `struct bp_target_info' and leaves
`placed_address' unchanged once it has been set. This ensures data in
`shadow_contents' is always consistent with `placed_address'.
This approach also has this good side effect that all the places that
examine the breakpoint's address see a consistent value, either
`reqstd_address' or `placed_address', as required. Currently some
places see either the original or the adjusted address in
`placed_address', depending on whether they have been called before
`gdbarch_remote_breakpoint_from_pc' or afterwards. This is in
particular true for subsequent calls to
`gdbarch_remote_breakpoint_from_pc' itself, e.g. from
`one_breakpoint_xfer_memory'. This is also important for places like
`find_single_step_breakpoint' where a breakpoint's address is compared
to the raw value of $pc.
* breakpoint.h (bp_target_info): Add `reqstd_address' member,
update comments.
* breakpoint.c (one_breakpoint_xfer_memory): Use `reqstd_address'
for the breakpoint's address. Don't preinitialize `placed_size'.
(insert_bp_location): Set `reqstd_address' rather than
`placed_address'.
(bp_target_info_copy_insertion_state): Also copy `placed_address'.
(bkpt_insert_location): Use `reqstd_address' for the breakpoint's
address.
(bkpt_remove_location): Likewise.
(deprecated_insert_raw_breakpoint): Likewise.
(deprecated_remove_raw_breakpoint): Likewise.
(find_single_step_breakpoint): Likewise.
* mem-break.c (default_memory_insert_breakpoint): Use
`reqstd_address' for the breakpoint's address. Don't set
`placed_address' or `placed_size' if breakpoint contents couldn't
have been determined.
* remote.c (remote_insert_breakpoint): Use `reqstd_address' for
the breakpoint's address.
(remote_insert_hw_breakpoint): Likewise. Don't set
`placed_address' or `placed_size' if breakpoint couldn't have been
set.
* aarch64-linux-nat.c (aarch64_linux_insert_hw_breakpoint): Use
`reqstd_address' for the breakpoint's address.
* arm-linux-nat.c (arm_linux_hw_breakpoint_initialize): Likewise.
* ia64-tdep.c (ia64_memory_insert_breakpoint): Likewise.
* m32r-tdep.c (m32r_memory_insert_breakpoint): Likewise.
* microblaze-linux-tdep.c
(microblaze_linux_memory_remove_breakpoint): Likewise.
* monitor.c (monitor_insert_breakpoint): Likewise.
* nto-procfs.c (procfs_insert_breakpoint): Likewise.
(procfs_insert_hw_breakpoint): Likewise.
* ppc-linux-nat.c (ppc_linux_insert_hw_breakpoint): Likewise.
* ppc-linux-tdep.c (ppc_linux_memory_remove_breakpoint): Likewise.
* remote-m32r-sdi.c (m32r_insert_breakpoint): Likewise.
* remote-mips.c (mips_insert_breakpoint): Likewise.
* x86-nat.c (x86_insert_hw_breakpoint): Likewise.
This commit adds a new global flag show_debug_regs to common-debug.h
to replace the flag debug_hw_points used by gdbserver and by the
Linux x86 and AArch64 ports, and to replace the flag maint_show_dr
used by the Linux MIPS port.
Note that some debug printing in the AArch64 port was enabled only if
debug_hw_points > 1 but no way to set debug_hw_points to values other
than 0 and 1 was provided; that code was effectively dead. This
commit enables all debug printing if show_debug_regs is nonzero, so
the AArch64 output will be more verbose than previously.
gdb/ChangeLog:
* common/common-debug.h (show_debug_regs): Declare.
* common/common-debug.c (show_debug_regs): Define.
* aarch64-linux-nat.c (debug_hw_points): Don't define. Replace
all uses with show_debug_regs. Replace all uses that considered
debug_hw_points as a multi-value integer with straight boolean
uses.
* x86-nat.c (debug_hw_points): Don't define. Replace all uses
with show_debug_regs.
* nat/x86-dregs.c (debug_hw_points): Don't declare. Replace
all uses with show_debug_regs.
* mips-linux-nat.c (maint_show_dr): Don't define. Replace all
uses with show_debug_regs.
gdb/gdbserver/ChangeLog:
* server.h (debug_hw_points): Don't declare.
* server.c (debug_hw_points): Don't define. Replace all uses
with show_debug_regs.
* linux-aarch64-low.c (debug_hw_points): Don't define. Replace
all uses with show_debug_regs.
This commit renames nine files that contain code used by both 32- and
64-bit Intel ports such that their names are prefixed with "x86"
rather than "i386". All types, functions and variables within these
files are likewise renamed such that their names are prefixed with
"x86" rather than "i386". This makes GDB follow the convention used
by gdbserver such that 32-bit Intel code lives in files called
"i386-*", 64-bit Intel code lives in files called "amd64-*", and code
for both 32- and 64-bit Intel lives in files called "x86-*".
This commit only renames OS-independent files. The Linux ports of
both GDB and gdbserver now follow the i386/amd64/x86 convention fully.
Some ports still use the old convention where "i386" in file/function/
type/variable names can mean "32-bit only" or "32- and 64-bit" but I
don't want to touch ports I can't fully test except where absolutely
necessary.
gdb/ChangeLog:
* i386-nat.h: Renamed as...
* x86-nat.h: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
* i386-nat.c: Renamed as...
* x86-nat.c: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
* common/i386-xstate.h: Renamed as...
* common/x86-xstate.h: New file. All type, function and variable
name prefixes changed from "i386_" to "x86_". All references
updated.
* nat/i386-cpuid.h: Renamed as...
* nat/x86-cpuid.h: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
* nat/i386-gcc-cpuid.h: Renamed as...
* nat/x86-gcc-cpuid.h: New file. All type, function and variable
name prefixes changed from "i386_" to "x86_". All references
updated.
* nat/i386-dregs.h: Renamed as...
* nat/x86-dregs.h: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
* nat/i386-dregs.c: Renamed as...
* nat/x86-dregs.c: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
gdb/gdbserver/ChangeLog:
* i386-low.h: Renamed as...
* x86-low.h: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
* i386-low.c: Renamed as...
* x86-low.c: New file. All type, function and variable name
prefixes changed from "i386_" to "x86_". All references updated.
Simon Marchi
Joel Brobecker
Maciej W. Rozycki
Gary Benson