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252 lines
9.6 KiB
252 lines
9.6 KiB
Message-ID: <5491BE7E.2060708@gmail.com> |
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Date: Thu, 18 Dec 2014 01:33:50 +0800 |
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From: Wei-cheng Wang <cole945 at gmail dot com> |
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To: Ulrich Weigand <uweigand at de dot ibm dot com> |
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CC: gdb-patches at sourceware dot org |
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Subject: Re: [PATCH 3/3 v2] Process record support for PowerPC |
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On 2014/12/9 上午 03:13, Ulrich Weigand wrote: |
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> Wei-cheng Wang wrote: |
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>> * ppc-linux-tdep.c (powerpc_linux_in_dynsym_resolve_code): |
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>> Scan PLT stub backward for reverse debugging. |
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>> (ppc_linux_init_abi): set powerpc_linux_in_dynsym_resolve_code |
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>> for both 32-bit and 64-bit. |
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> |
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> As I said in the reply to the 0/3 mail, I really think it would be |
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> better to handle this within the PPC skip_trampoline_code implementation, |
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> instead of having in_dynsym_resolve_code suddenly also cover the |
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> trampolines ... |
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Hi, |
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See the new patch, I moved the for-loop into skip_trampoline_code, |
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and removed in_dynsym_resolve_code. |
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> It seems odd to have in_dynsym_resolve_code call into |
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> skip_trampoline_code. Is there a reason why the skip_trampoline_code |
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> implementation cannot accept a PC in the middle of the sequence? |
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I thought skip-trampoline is used to find the target address for |
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inserting step-resume breakpoint, so it doesn't make sense for |
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reverse-stepping, because we are just stepping from the target address. |
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And for forward-stepping, when we reach the very first instruction of |
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trampoline code, we can just skip the resolving code by inserting |
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a step-resume breakpoint, so we don't have to step through the resolving |
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code and check whether we are in the middle of trampoline code. |
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in_dynsym_resolve_code is used to check whether we are in (the middle of) |
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the resolving code, so we can keep going to step though the resolving code. |
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Therefor I thought in_dynsym_resolve_code is the proper place to implement. |
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Since skip-trampoline-code had implemented the plt-stub pattern-match code |
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we need, by calling it in in-dynsym-resolve-code, we don't need to have |
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duplicate pattern-match code in both functions. |
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Wei-cheng, |
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Thanks |
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-- |
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2014-12-06 Wei-cheng Wang <cole945@gmail.com> |
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* ppc-linux-tdep.c (ppc_skip_trampoline_code): |
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Scan PLT stub backward for reverse debugging. |
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* ppc64-tdep.c (ppc64_skip_trampoline_code): Likewise. |
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commit cf90fd9a07e8998540bf74f293d348a6653ac120 |
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Author: Wei-cheng Wang <cole945@gmail.com> |
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Date: Sat Jan 17 14:30:59 2015 +0800 |
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Skip-trampoline for PowerPC reverse-stepping. |
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Index: gdb-7.6.1/gdb/ppc64-tdep.c |
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=================================================================== |
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--- gdb-7.6.1.orig/gdb/ppc64-tdep.c |
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+++ gdb-7.6.1/gdb/ppc64-tdep.c |
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@@ -20,6 +20,7 @@ |
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#include "defs.h" |
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#include "frame.h" |
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#include "gdbcore.h" |
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+#include "inferior.h" |
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#include "ppc-tdep.h" |
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#include "ppc64-tdep.h" |
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#include "elf-bfd.h" |
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@@ -464,35 +465,66 @@ ppc64_skip_trampoline_code (struct frame |
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ARRAY_SIZE (ppc64_standard_linkage8)))) |
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- 1]; |
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CORE_ADDR target; |
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+ int scan_limit, i; |
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|
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- if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage8, insns)) |
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- pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage7, insns)) |
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- pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage6, insns)) |
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- pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage5, insns) |
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- && (insns[8] != 0 || insns[9] != 0)) |
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- pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage4, insns) |
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- && (insns[9] != 0 || insns[10] != 0)) |
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- pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage3, insns) |
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- && (insns[8] != 0 || insns[9] != 0)) |
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- pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage2, insns) |
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- && (insns[10] != 0 || insns[11] != 0)) |
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- pc = ppc64_standard_linkage2_target (frame, pc, insns); |
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- else if (ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage1, insns)) |
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- pc = ppc64_standard_linkage1_target (frame, pc, insns); |
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- else |
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- return 0; |
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- |
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- /* The PLT descriptor will either point to the already resolved target |
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- address, or else to a glink stub. As the latter carry synthetic @plt |
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- symbols, find_solib_trampoline_target should be able to resolve them. */ |
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- target = find_solib_trampoline_target (frame, pc); |
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- return target ? target : pc; |
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+ scan_limit = 1; |
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+ /* When reverse-debugging, scan backward to check whether we are |
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+ in the middle of trampoline code. */ |
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+ if (execution_direction == EXEC_REVERSE) |
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+ scan_limit = ARRAY_SIZE (insns) - 1; |
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+ |
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+ for (i = 0; i < scan_limit; i++) |
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+ { |
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+ if (i < ARRAY_SIZE (ppc64_standard_linkage8) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage8, insns)) |
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+ pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage7) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage7, |
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+ insns)) |
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+ pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage6) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage6, |
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+ insns)) |
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+ pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage5) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage5, |
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+ insns) |
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+ && (insns[8] != 0 || insns[9] != 0)) |
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+ pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage4) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage4, |
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+ insns) |
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+ && (insns[9] != 0 || insns[10] != 0)) |
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+ pc = ppc64_standard_linkage4_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage3) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage3, |
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+ insns) |
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+ && (insns[8] != 0 || insns[9] != 0)) |
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+ pc = ppc64_standard_linkage3_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage2) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage2, |
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+ insns) |
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+ && (insns[10] != 0 || insns[11] != 0)) |
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+ pc = ppc64_standard_linkage2_target (frame, pc, insns); |
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+ else if (i < ARRAY_SIZE (ppc64_standard_linkage1) - 1 |
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+ && ppc_insns_match_pattern (frame, pc, ppc64_standard_linkage1, |
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+ insns)) |
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+ pc = ppc64_standard_linkage1_target (frame, pc, insns); |
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+ else |
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+ { |
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+ /* Scan backward one more instructions if doesn't match. */ |
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+ pc -= 4; |
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+ continue; |
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+ } |
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+ |
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+ /* The PLT descriptor will either point to the already resolved target |
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+ address, or else to a glink stub. As the latter carry synthetic @plt |
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+ symbols, find_solib_trampoline_target should be able to resolve them. */ |
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+ target = find_solib_trampoline_target (frame, pc); |
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+ return target ? target : pc; |
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+ } |
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+ |
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+ return 0; |
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} |
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/* Support for convert_from_func_ptr_addr (ARCH, ADDR, TARG) on PPC64 |
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Index: gdb-7.6.1/gdb/ppc-linux-tdep.c |
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=================================================================== |
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--- gdb-7.6.1.orig/gdb/ppc-linux-tdep.c |
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+++ gdb-7.6.1/gdb/ppc-linux-tdep.c |
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@@ -52,6 +52,7 @@ |
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#include "linux-tdep.h" |
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#include "linux-record.h" |
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#include "record-full.h" |
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+#include "inferior.h" |
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#include "stap-probe.h" |
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#include "ax.h" |
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@@ -362,31 +363,50 @@ ppc_skip_trampoline_code (struct frame_i |
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struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); |
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enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
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CORE_ADDR target = 0; |
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+ int scan_limit, i; |
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- if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub, insnbuf)) |
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- { |
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- /* Insn pattern is |
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- lis r11, xxxx |
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- lwz r11, xxxx(r11) |
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- Branch target is in r11. */ |
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- |
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- target = (ppc_insn_d_field (insnbuf[0]) << 16) |
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- | ppc_insn_d_field (insnbuf[1]); |
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- target = read_memory_unsigned_integer (target, 4, byte_order); |
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- } |
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+ scan_limit = 1; |
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+ /* When reverse-debugging, scan backward to check whether we are |
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+ in the middle of trampoline code. */ |
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+ if (execution_direction == EXEC_REVERSE) |
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+ scan_limit = 4; /* At more 4 instructions. */ |
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- if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub_so, insnbuf)) |
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+ for (i = 0; i < scan_limit; i++) |
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{ |
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- /* Insn pattern is |
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- lwz r11, xxxx(r30) |
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- Branch target is in r11. */ |
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- |
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- target = get_frame_register_unsigned (frame, tdep->ppc_gp0_regnum + 30) |
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- + ppc_insn_d_field (insnbuf[0]); |
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- target = read_memory_unsigned_integer (target, 4, byte_order); |
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+ if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub, insnbuf)) |
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+ { |
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+ /* Insn pattern is |
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+ lis r11, xxxx |
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+ lwz r11, xxxx(r11) |
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+ Branch target is in r11. */ |
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+ |
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+ target = (ppc_insn_d_field (insnbuf[0]) << 16) |
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+ | ppc_insn_d_field (insnbuf[1]); |
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+ target = read_memory_unsigned_integer (target, 4, byte_order); |
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+ } |
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+ else if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub_so, |
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+ insnbuf)) |
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+ { |
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+ /* Insn pattern is |
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+ lwz r11, xxxx(r30) |
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+ Branch target is in r11. */ |
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+ |
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+ target = get_frame_register_unsigned (frame, |
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+ tdep->ppc_gp0_regnum + 30) |
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+ + ppc_insn_d_field (insnbuf[0]); |
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+ target = read_memory_unsigned_integer (target, 4, byte_order); |
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+ } |
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+ else |
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+ { |
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+ /* Scan backward one more instructions if doesn't match. */ |
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+ pc -= 4; |
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+ continue; |
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+ } |
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+ |
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+ return target; |
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} |
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- return target; |
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+ return 0; |
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} |
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/* Wrappers to handle Linux-only registers. */
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