| From 16ddc17b4f403a38701e0108b02aff967900cc66 Mon Sep 17 00:00:00 2001 |
| From: Anton Kolesov <Anton.Kolesov@synopsys.com> |
| Date: Thu, 22 Dec 2016 21:52:16 +0300 |
| Subject: [PATCH 2/4] arc: Add support for signal frames for Linux targets |
| |
| Implement functions needed to unwind signal frames on ARC Linux targets. |
| |
| gdb/ChangeLog |
| |
| * arc-linux-tdep.c (arc_linux_sc_reg_offsets): New static variable. |
| (arc_linux_is_sigtramp): New function. |
| (arc_linux_sigcontext_addr): Likewise. |
| (arc_linux_init_osabi): Use them. |
| |
| Upstream-Status: Backport [https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d4af727286e3a9f177ba11677fbd3a012d36558a] |
| |
| Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com> |
| Signed-off-by: Shahab Vahedi <shahab@synopsys.com> |
| Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> |
| --- |
| gdb/arc-linux-tdep.c | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++ |
| 1 file changed, 181 insertions(+) |
| |
| diff --git a/gdb/arc-linux-tdep.c b/gdb/arc-linux-tdep.c |
| index a7bace12623..17bb3e7b276 100644 |
| --- a/gdb/arc-linux-tdep.c |
| +++ b/gdb/arc-linux-tdep.c |
| @@ -33,6 +33,60 @@ |
| |
| #define REGOFF(offset) (offset * ARC_REGISTER_SIZE) |
| |
| +/* arc_linux_sc_reg_offsets[i] is the offset of register i in the `struct |
| + sigcontext'. Array index is an internal GDB register number, as defined in |
| + arc-tdep.h:arc_regnum. |
| + |
| + From <include/uapi/asm/sigcontext.h> and <include/uapi/asm/ptrace.h>. |
| + |
| + The layout of this struct is tightly bound to "arc_regnum" enum |
| + in arc-tdep.h. Any change of order in there, must be reflected |
| + here as well. */ |
| +static const int arc_linux_sc_reg_offsets[] = { |
| + /* R0 - R12. */ |
| + REGOFF (22), REGOFF (21), REGOFF (20), REGOFF (19), |
| + REGOFF (18), REGOFF (17), REGOFF (16), REGOFF (15), |
| + REGOFF (14), REGOFF (13), REGOFF (12), REGOFF (11), |
| + REGOFF (10), |
| + |
| + /* R13 - R25. */ |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, |
| + |
| + REGOFF (9), /* R26 (GP) */ |
| + REGOFF (8), /* FP */ |
| + REGOFF (23), /* SP */ |
| + ARC_OFFSET_NO_REGISTER, /* ILINK */ |
| + ARC_OFFSET_NO_REGISTER, /* R30 */ |
| + REGOFF (7), /* BLINK */ |
| + |
| + /* R32 - R59. */ |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, ARC_OFFSET_NO_REGISTER, |
| + ARC_OFFSET_NO_REGISTER, |
| + |
| + REGOFF (4), /* LP_COUNT */ |
| + ARC_OFFSET_NO_REGISTER, /* RESERVED */ |
| + ARC_OFFSET_NO_REGISTER, /* LIMM */ |
| + ARC_OFFSET_NO_REGISTER, /* PCL */ |
| + |
| + REGOFF (6), /* PC */ |
| + REGOFF (5), /* STATUS32 */ |
| + REGOFF (2), /* LP_START */ |
| + REGOFF (3), /* LP_END */ |
| + REGOFF (1), /* BTA */ |
| +}; |
| + |
| /* arc_linux_core_reg_offsets[i] is the offset in the .reg section of GDB |
| regnum i. Array index is an internal GDB register number, as defined in |
| arc-tdep.h:arc_regnum. |
| @@ -87,6 +141,127 @@ static const int arc_linux_core_reg_offsets[] = { |
| REGOFF (6) /* ERET */ |
| }; |
| |
| +/* Is THIS_FRAME a sigtramp function - the function that returns from |
| + signal handler into normal execution flow? This is the case if the PC is |
| + either at the start of, or in the middle of the two instructions: |
| + |
| + mov r8, __NR_rt_sigreturn ; __NR_rt_sigreturn == 139 |
| + trap_s 0 ; `swi' for ARC700 |
| + |
| + On ARC uClibc Linux this function is called __default_rt_sa_restorer. |
| + |
| + Returns TRUE if this is a sigtramp frame. */ |
| + |
| +static bool |
| +arc_linux_is_sigtramp (struct frame_info *this_frame) |
| +{ |
| + struct gdbarch *gdbarch = get_frame_arch (this_frame); |
| + CORE_ADDR pc = get_frame_pc (this_frame); |
| + |
| + if (arc_debug) |
| + { |
| + debug_printf ("arc-linux: arc_linux_is_sigtramp, pc=%s\n", |
| + paddress(gdbarch, pc)); |
| + } |
| + |
| + static const gdb_byte insns_be_hs[] = { |
| + 0x20, 0x8a, 0x12, 0xc2, /* mov r8,nr_rt_sigreturn */ |
| + 0x78, 0x1e /* trap_s 0 */ |
| + }; |
| + static const gdb_byte insns_be_700[] = { |
| + 0x20, 0x8a, 0x12, 0xc2, /* mov r8,nr_rt_sigreturn */ |
| + 0x22, 0x6f, 0x00, 0x3f /* swi */ |
| + }; |
| + |
| + gdb_byte arc_sigtramp_insns[sizeof (insns_be_700)]; |
| + size_t insns_sz; |
| + if (arc_mach_is_arcv2 (gdbarch)) |
| + { |
| + insns_sz = sizeof (insns_be_hs); |
| + memcpy (arc_sigtramp_insns, insns_be_hs, insns_sz); |
| + } |
| + else |
| + { |
| + insns_sz = sizeof (insns_be_700); |
| + memcpy (arc_sigtramp_insns, insns_be_700, insns_sz); |
| + } |
| + if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_LITTLE) |
| + { |
| + /* On little endian targets, ARC code section is in what is called |
| + "middle endian", where half-words are in the big-endian order, |
| + only bytes inside the halfwords are in the little endian order. |
| + As a result it is very easy to convert big endian instruction to |
| + little endian, since it is needed to swap bytes in the halfwords, |
| + so there is no need to have information on whether that is a |
| + 4-byte instruction or 2-byte. */ |
| + gdb_assert ((insns_sz % 2) == 0); |
| + for (int i = 0; i < insns_sz; i += 2) |
| + std::swap (arc_sigtramp_insns[i], arc_sigtramp_insns[i+1]); |
| + } |
| + |
| + gdb_byte buf[insns_sz]; |
| + |
| + /* Read the memory at the PC. Since we are stopped, any breakpoint must |
| + have been removed. */ |
| + if (!safe_frame_unwind_memory (this_frame, pc, buf, insns_sz)) |
| + { |
| + /* Failed to unwind frame. */ |
| + return FALSE; |
| + } |
| + |
| + /* Is that code the sigtramp instruction sequence? */ |
| + if (memcmp (buf, arc_sigtramp_insns, insns_sz) == 0) |
| + return TRUE; |
| + |
| + /* No - look one instruction earlier in the code... */ |
| + if (!safe_frame_unwind_memory (this_frame, pc - 4, buf, insns_sz)) |
| + { |
| + /* Failed to unwind frame. */ |
| + return FALSE; |
| + } |
| + |
| + return (memcmp (buf, arc_sigtramp_insns, insns_sz) == 0); |
| +} |
| + |
| +/* Get sigcontext structure of sigtramp frame - it contains saved |
| + registers of interrupted frame. |
| + |
| + Stack pointer points to the rt_sigframe structure, and sigcontext can |
| + be found as in: |
| + |
| + struct rt_sigframe { |
| + struct siginfo info; |
| + struct ucontext uc; |
| + ... |
| + }; |
| + |
| + struct ucontext { |
| + unsigned long uc_flags; |
| + struct ucontext *uc_link; |
| + stack_t uc_stack; |
| + struct sigcontext uc_mcontext; |
| + sigset_t uc_sigmask; |
| + }; |
| + |
| + sizeof (struct siginfo) == 0x80 |
| + offsetof (struct ucontext, uc_mcontext) == 0x14 |
| + |
| + GDB cannot include linux headers and use offsetof () because those are |
| + target headers and GDB might be built for a different run host. There |
| + doesn't seem to be an established mechanism to figure out those offsets |
| + via gdbserver, so the only way is to hardcode values in the GDB, |
| + meaning that GDB will be broken if values will change. That seems to |
| + be a very unlikely scenario and other arches (aarch64, alpha, amd64, |
| + etc) in GDB hardcode values. */ |
| + |
| +static CORE_ADDR |
| +arc_linux_sigcontext_addr (struct frame_info *this_frame) |
| +{ |
| + const int ucontext_offset = 0x80; |
| + const int sigcontext_offset = 0x14; |
| + return get_frame_sp (this_frame) + ucontext_offset + sigcontext_offset; |
| +} |
| + |
| /* Implement the "cannot_fetch_register" gdbarch method. */ |
| |
| static int |
| @@ -504,6 +679,12 @@ arc_linux_init_osabi (struct gdbarch_info info, struct gdbarch *gdbarch) |
| if (arc_debug) |
| debug_printf ("arc-linux: GNU/Linux OS/ABI initialization.\n"); |
| |
| + /* Fill in target-dependent info in ARC-private structure. */ |
| + tdep->is_sigtramp = arc_linux_is_sigtramp; |
| + tdep->sigcontext_addr = arc_linux_sigcontext_addr; |
| + tdep->sc_reg_offset = arc_linux_sc_reg_offsets; |
| + tdep->sc_num_regs = ARRAY_SIZE (arc_linux_sc_reg_offsets); |
| + |
| /* If we are using Linux, we have in uClibc |
| (libc/sysdeps/linux/arc/bits/setjmp.h): |
| |
| -- |
| 2.16.2 |
| |