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8099a74750
Here we add a couple of fixes and improvements for ARC processors. All except 1 patch are already in the upstream "master" branch and will be an essential part of GCC 11.x whenever it gets released. The most important are first 4 patches (0005-0008) which introduce support of full native GDB support in Linux on ARC. And the rests are tiny, yet useful improvements. Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
241 lines
8.3 KiB
Diff
241 lines
8.3 KiB
Diff
From 27a456bbaa0c525e534195d17345c2e9268dd5d2 Mon Sep 17 00:00:00 2001
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From: Anton Kolesov <Anton.Kolesov@synopsys.com>
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Date: Thu, 22 Dec 2016 21:52:16 +0300
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Subject: [PATCH 07/20] arc: Add support for signal frames for Linux targets
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Implement functions needed to unwind signal frames on ARC Linux targets.
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gdb/ChangeLog
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* arc-linux-tdep.c (arc_linux_sc_reg_offsets): New static variable.
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(arc_linux_is_sigtramp): New function.
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(arc_linux_sigcontext_addr): Likewise.
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(arc_linux_init_osabi): Use them.
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Will be a part of GDB 11:
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https://sourceware.org/git?p=binutils-gdb.git;a=commit;h=d4af727286e3a9f177ba11677fbd3a012d36558a
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---
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gdb/ChangeLog | 7 +
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gdb/arc-linux-tdep.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++
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2 files changed, 188 insertions(+)
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--- a/gdb/ChangeLog
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+++ b/gdb/ChangeLog
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@@ -1,5 +1,12 @@
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2020-12-22 Anton Kolesov <anton.kolesov@synopsys.com>
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+ * arc-linux-tdep.c (arc_linux_sc_reg_offsets): New static variable.
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+ (arc_linux_is_sigtramp): New function.
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+ (arc_linux_sigcontext_addr): Likewise.
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+ (arc_linux_init_osabi): Use them.
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+
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+2020-12-22 Anton Kolesov <anton.kolesov@synopsys.com>
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+
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* arc-tdep.c (arc_make_sigtramp_frame_cache): New function.
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(arc_sigtramp_frame_this_id): Likewise.
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(arc_sigtramp_frame_prev_register): Likewise.
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--- a/gdb/arc-linux-tdep.c
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+++ b/gdb/arc-linux-tdep.c
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@@ -33,6 +33,60 @@
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#define REGOFF(offset) (offset * ARC_REGISTER_SIZE)
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+/* arc_linux_sc_reg_offsets[i] is the offset of register i in the `struct
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+ sigcontext'. Array index is an internal GDB register number, as defined in
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+ arc-tdep.h:arc_regnum.
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+
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+ From <include/uapi/asm/sigcontext.h> and <include/uapi/asm/ptrace.h>.
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+
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+ The layout of this struct is tightly bound to "arc_regnum" enum
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+ in arc-tdep.h. Any change of order in there, must be reflected
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+ here as well. */
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+static const int arc_linux_sc_reg_offsets[] = {
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+ /* R0 - R12. */
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+ REGOFF (22), REGOFF (21), REGOFF (20), REGOFF (19),
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+ REGOFF (18), REGOFF (17), REGOFF (16), REGOFF (15),
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+ REGOFF (14), REGOFF (13), REGOFF (12), REGOFF (11),
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+ REGOFF (10),
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+
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+ /* R13 - R25. */
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER,
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+
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+ REGOFF (9), /* R26 (GP) */
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+ REGOFF (8), /* FP */
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+ REGOFF (23), /* SP */
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+ ARC_OFFSET_NO_REGISTER, /* ILINK */
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+ ARC_OFFSET_NO_REGISTER, /* R30 */
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+ REGOFF (7), /* BLINK */
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+
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+ /* R32 - R59. */
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER,
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+ ARC_OFFSET_NO_REGISTER,
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+
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+ REGOFF (4), /* LP_COUNT */
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+ ARC_OFFSET_NO_REGISTER, /* RESERVED */
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+ ARC_OFFSET_NO_REGISTER, /* LIMM */
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+ ARC_OFFSET_NO_REGISTER, /* PCL */
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+
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+ REGOFF (6), /* PC */
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+ REGOFF (5), /* STATUS32 */
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+ REGOFF (2), /* LP_START */
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+ REGOFF (3), /* LP_END */
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+ REGOFF (1), /* BTA */
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+};
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+
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/* arc_linux_core_reg_offsets[i] is the offset in the .reg section of GDB
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regnum i. Array index is an internal GDB register number, as defined in
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arc-tdep.h:arc_regnum.
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@@ -87,6 +141,127 @@
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REGOFF (6) /* ERET */
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};
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+/* Is THIS_FRAME a sigtramp function - the function that returns from
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+ signal handler into normal execution flow? This is the case if the PC is
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+ either at the start of, or in the middle of the two instructions:
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+
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+ mov r8, __NR_rt_sigreturn ; __NR_rt_sigreturn == 139
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+ trap_s 0 ; `swi' for ARC700
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+
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+ On ARC uClibc Linux this function is called __default_rt_sa_restorer.
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+
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+ Returns TRUE if this is a sigtramp frame. */
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+
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+static bool
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+arc_linux_is_sigtramp (struct frame_info *this_frame)
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+{
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+ struct gdbarch *gdbarch = get_frame_arch (this_frame);
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+ CORE_ADDR pc = get_frame_pc (this_frame);
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+
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+ if (arc_debug)
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+ {
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+ debug_printf ("arc-linux: arc_linux_is_sigtramp, pc=%s\n",
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+ paddress(gdbarch, pc));
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+ }
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+
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+ static const gdb_byte insns_be_hs[] = {
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+ 0x20, 0x8a, 0x12, 0xc2, /* mov r8,nr_rt_sigreturn */
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+ 0x78, 0x1e /* trap_s 0 */
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+ };
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+ static const gdb_byte insns_be_700[] = {
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+ 0x20, 0x8a, 0x12, 0xc2, /* mov r8,nr_rt_sigreturn */
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+ 0x22, 0x6f, 0x00, 0x3f /* swi */
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+ };
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+
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+ gdb_byte arc_sigtramp_insns[sizeof (insns_be_700)];
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+ size_t insns_sz;
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+ if (arc_mach_is_arcv2 (gdbarch))
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+ {
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+ insns_sz = sizeof (insns_be_hs);
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+ memcpy (arc_sigtramp_insns, insns_be_hs, insns_sz);
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+ }
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+ else
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+ {
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+ insns_sz = sizeof (insns_be_700);
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+ memcpy (arc_sigtramp_insns, insns_be_700, insns_sz);
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+ }
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+ if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_LITTLE)
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+ {
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+ /* On little endian targets, ARC code section is in what is called
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+ "middle endian", where half-words are in the big-endian order,
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+ only bytes inside the halfwords are in the little endian order.
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+ As a result it is very easy to convert big endian instruction to
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+ little endian, since it is needed to swap bytes in the halfwords,
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+ so there is no need to have information on whether that is a
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+ 4-byte instruction or 2-byte. */
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+ gdb_assert ((insns_sz % 2) == 0);
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+ for (int i = 0; i < insns_sz; i += 2)
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+ std::swap (arc_sigtramp_insns[i], arc_sigtramp_insns[i+1]);
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+ }
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+
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+ gdb_byte buf[insns_sz];
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+
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+ /* Read the memory at the PC. Since we are stopped, any breakpoint must
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+ have been removed. */
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+ if (!safe_frame_unwind_memory (this_frame, pc, buf, insns_sz))
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+ {
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+ /* Failed to unwind frame. */
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+ return FALSE;
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+ }
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+
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+ /* Is that code the sigtramp instruction sequence? */
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+ if (memcmp (buf, arc_sigtramp_insns, insns_sz) == 0)
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+ return TRUE;
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+
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+ /* No - look one instruction earlier in the code... */
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+ if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, insns_sz))
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+ {
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+ /* Failed to unwind frame. */
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+ return FALSE;
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+ }
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+
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+ return (memcmp (buf, arc_sigtramp_insns, insns_sz) == 0);
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+}
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+
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+/* Get sigcontext structure of sigtramp frame - it contains saved
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+ registers of interrupted frame.
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+
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+ Stack pointer points to the rt_sigframe structure, and sigcontext can
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+ be found as in:
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+
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+ struct rt_sigframe {
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+ struct siginfo info;
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+ struct ucontext uc;
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+ ...
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+ };
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+
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+ struct ucontext {
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+ unsigned long uc_flags;
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+ struct ucontext *uc_link;
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+ stack_t uc_stack;
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+ struct sigcontext uc_mcontext;
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+ sigset_t uc_sigmask;
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+ };
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+
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+ sizeof (struct siginfo) == 0x80
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+ offsetof (struct ucontext, uc_mcontext) == 0x14
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+
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+ GDB cannot include linux headers and use offsetof () because those are
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+ target headers and GDB might be built for a different run host. There
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+ doesn't seem to be an established mechanism to figure out those offsets
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+ via gdbserver, so the only way is to hardcode values in the GDB,
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+ meaning that GDB will be broken if values will change. That seems to
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+ be a very unlikely scenario and other arches (aarch64, alpha, amd64,
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+ etc) in GDB hardcode values. */
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+
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+static CORE_ADDR
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+arc_linux_sigcontext_addr (struct frame_info *this_frame)
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+{
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+ const int ucontext_offset = 0x80;
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+ const int sigcontext_offset = 0x14;
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+ return get_frame_sp (this_frame) + ucontext_offset + sigcontext_offset;
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+}
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+
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/* Implement the "cannot_fetch_register" gdbarch method. */
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static int
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@@ -504,6 +679,12 @@
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if (arc_debug)
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debug_printf ("arc-linux: GNU/Linux OS/ABI initialization.\n");
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+ /* Fill in target-dependent info in ARC-private structure. */
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+ tdep->is_sigtramp = arc_linux_is_sigtramp;
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+ tdep->sigcontext_addr = arc_linux_sigcontext_addr;
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+ tdep->sc_reg_offset = arc_linux_sc_reg_offsets;
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+ tdep->sc_num_regs = ARRAY_SIZE (arc_linux_sc_reg_offsets);
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+
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/* If we are using Linux, we have in uClibc
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(libc/sysdeps/linux/arc/bits/setjmp.h):
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