From 012b3a217a60cc74b802b059029c72a25d77808c Mon Sep 17 00:00:00 2001 From: Walfred Tedeschi Date: Thu, 18 Feb 2016 17:24:59 +0100 Subject: Intel MPX bound violation handling With Intel Memory Protection Extensions it was introduced the concept of boundary violation. A boundary violations is presented to the inferior as a segmentation fault having SIGCODE 3. This patch adds a handler for a boundary violation extending the information displayed when a bound violation is presented to the inferior. In the stop mode case the debugger will also display the kind of violation: "upper" or "lower", bounds and the address accessed. On no stop mode the information will still remain unchanged. Additional information about bound violations are not meaningful in that case user does not know the line in which violation occurred as well. When the segmentation fault handler is stop mode the out puts will be changed as exemplified below. The usual output of a segfault is: Program received signal SIGSEGV, Segmentation fault 0x0000000000400d7c in upper (p=0x603010, a=0x603030, b=0x603050, c=0x603070, d=0x603090, len=7) at i386-mpx-sigsegv.c:68 68 value = *(p + len); In case it is a bound violation it will be presented as: Program received signal SIGSEGV, Segmentation fault Upper bound violation while accessing address 0x7fffffffc3b3 Bounds: [lower = 0x7fffffffc390, upper = 0x7fffffffc3a3] 0x0000000000400d7c in upper (p=0x603010, a=0x603030, b=0x603050, c=0x603070, d=0x603090, len=7) at i386-mpx-sigsegv.c:68 68 value = *(p + len); In mi mode the output of a segfault is: *stopped,reason="signal-received",signal-name="SIGSEGV", signal-meaning="Segmentation fault", frame={addr="0x0000000000400d7c", func="upper",args=[{name="p", value="0x603010"},{name="a",value="0x603030"} ,{name="b",value="0x603050"}, {name="c",value="0x603070"}, {name="d",value="0x603090"},{name="len",value="7"}], file="i386-mpx-sigsegv.c",fullname="i386-mpx-sigsegv.c",line="68"}, thread-id="1",stopped-threads="all",core="6" in the case of a bound violation: *stopped,reason="signal-received",signal-name="SIGSEGV", signal-meaning="Segmentation fault", sigcode-meaning="Upper bound violation", lower-bound="0x603010",upper-bound="0x603023",bound-access="0x60302f", frame={addr="0x0000000000400d7c",func="upper",args=[{name="p", value="0x603010"},{name="a",value="0x603030"},{name="b",value="0x603050"}, {name="c",value="0x603070"},{name="d",value="0x603090"}, {name="len",value="7"}],file="i386-mpx-sigsegv.c", fullname="i386-mpx-sigsegv.c",line="68"},thread-id="1", stopped-threads="all",core="6" 2016-02-18 Walfred Tedeschi gdb/ChangeLog: * NEWS: Add entry for bound violation. * amd64-linux-tdep.c (amd64_linux_init_abi_common): Add handler for segmentation fault. * gdbarch.sh (handle_segmentation_fault): New. * gdbarch.c: Regenerate. * gdbarch.h: Regenerate. * i386-linux-tdep.c (i386_linux_handle_segmentation_fault): New. (SIG_CODE_BONDARY_FAULT): New define. (i386_linux_init_abi): Use i386_mpx_bound_violation_handler. * i386-linux-tdep.h (i386_linux_handle_segmentation_fault) New. * i386-tdep.c (i386_mpx_enabled): Add as external. * i386-tdep.c (i386_mpx_enabled): Add as external. * infrun.c (handle_segmentation_fault): New function. (print_signal_received_reason): Use handle_segmentation_fault. gdb/testsuite/ChangeLog: * gdb.arch/i386-mpx-sigsegv.c: New file. * gdb.arch/i386-mpx-sigsegv.exp: New file. * gdb.arch/i386-mpx-simple_segv.c: New file. * gdb.arch/i386-mpx-simple_segv.exp: New file. gdb/doc/ChangeLog: * gdb.texinfo (Signals): Add bound violation display hints for a SIGSEGV. --- gdb/i386-linux-tdep.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'gdb/i386-linux-tdep.h') diff --git a/gdb/i386-linux-tdep.h b/gdb/i386-linux-tdep.h index ecc9e315d7b..5c7a7f61c46 100644 --- a/gdb/i386-linux-tdep.h +++ b/gdb/i386-linux-tdep.h @@ -37,6 +37,11 @@ /* Get XSAVE extended state xcr0 from core dump. */ extern uint64_t i386_linux_core_read_xcr0 (bfd *abfd); +/* Handle and display information related to the MPX bound violation + to the user. */ +extern void i386_linux_handle_segmentation_fault (struct gdbarch *gdbarch, + struct ui_out *uiout); + /* Linux target description. */ extern struct target_desc *tdesc_i386_linux; extern struct target_desc *tdesc_i386_mmx_linux; -- cgit v1.2.3-65-gdbad