From e3d528d7e6a6b863d30aaecf74adf8c78286f84c Mon Sep 17 00:00:00 2001 From: Will Schmidt Date: Mon, 12 Apr 2021 13:35:54 -0500 Subject: [PATCH] [PATCH, rs6000, v3][PR gdb/27525] displaced stepping across addpcis/lnia. This addresses PR gdb/27525. The lnia and other variations of the addpcis instruction write the value of the NIA into a target register. If we are single-stepping across a breakpoint, the instruction is executed from a displaced location, and thusly the written value of the PC/NIA will be incorrect. The changes here will measure the displacement offset, and adjust the target register value to compensate. YYYY-MM-DD Will Schmidt gdb/ChangeLog: * rs6000-tdep.c (ppc_displaced_step_fixup): Update to handle the addpcis/lnia instruction. gdb/testsuite/ChangeLog: * gdb.arch/powerpc-addpcis.exp: Testcase harness to exercise single-stepping over subpcis,lnia,addpcis instructions with displacement. * gdb.arch/powerpc-addpcis.s: Testcase with stream of addpcis/lnia/subpcis instructions. * gdb.arch/powerpc-lnia.exp: Testcase harness to exercise single-stepping over lnia instructions with displacement. * gdb.arch/powerpc-lnia.s: Testcase with stream of lnia instructions. --- gdb/ChangeLog | 6 ++ gdb/rs6000-tdep.c | 27 +++++- gdb/testsuite/ChangeLog | 13 +++ gdb/testsuite/gdb.arch/powerpc-addpcis.exp | 105 +++++++++++++++++++++ gdb/testsuite/gdb.arch/powerpc-addpcis.s | 35 +++++++ gdb/testsuite/gdb.arch/powerpc-lnia.exp | 101 ++++++++++++++++++++ gdb/testsuite/gdb.arch/powerpc-lnia.s | 33 +++++++ 7 files changed, 319 insertions(+), 1 deletion(-) create mode 100644 gdb/testsuite/gdb.arch/powerpc-addpcis.exp create mode 100644 gdb/testsuite/gdb.arch/powerpc-addpcis.s create mode 100644 gdb/testsuite/gdb.arch/powerpc-lnia.exp create mode 100644 gdb/testsuite/gdb.arch/powerpc-lnia.s diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 4798523b610..fe52581fa52 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,11 @@ 2021-04-12 Will Schmidt + PR gdb/27525 + * gdb/rs6000-tdep.c (ppc_displaced_step_fixup): Update to + handle the addpcis/lnia instruction. + +2021-04-05 Will Schmidt + * MAINTAINERS (Write After Approval): Add myself. 2021-4-12 Carl Love diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c index 276b4fa5583..7a5b4bf647c 100644 --- a/gdb/rs6000-tdep.c +++ b/gdb/rs6000-tdep.c @@ -863,6 +863,12 @@ typedef BP_MANIPULATION_ENDIAN (little_breakpoint, big_breakpoint) #define STHCX_INSTRUCTION 0x7c0005ad #define STQCX_INSTRUCTION 0x7c00016d +/* Instruction masks for single-stepping of addpcis/lnia. */ +#define ADDPCIS_INSN 0x4c000004 +#define ADDPCIS_INSN_MASK 0xfc00003e +#define ADDPCIS_TARGET_REGISTER 0x03F00000 +#define ADDPCIS_INSN_REGSHIFT 21 + /* Check if insn is one of the Load And Reserve instructions used for atomic sequences. */ #define IS_LOAD_AND_RESERVE_INSN(insn) ((insn & LOAD_AND_RESERVE_MASK) == LWARX_INSTRUCTION \ @@ -941,8 +947,27 @@ ppc_displaced_step_fixup (struct gdbarch *gdbarch, displaced_debug_printf ("(ppc) fixup (%s, %s)", paddress (gdbarch, from), paddress (gdbarch, to)); + /* Handle the addpcis/lnia instruction. */ + if ((insn & ADDPCIS_INSN_MASK) == ADDPCIS_INSN) + { + LONGEST displaced_offset; + ULONGEST current_val; + /* Measure the displacement. */ + displaced_offset = from - to; + /* Identify the target register that was updated by the instruction. */ + int regnum = (insn & ADDPCIS_TARGET_REGISTER) >> ADDPCIS_INSN_REGSHIFT; + /* Read and update the target value. */ + regcache_cooked_read_unsigned (regs, regnum , ¤t_val); + displaced_debug_printf ("addpcis target regnum %d was 0x%lx now 0x%lx", + regnum, current_val, current_val + displaced_offset ); + regcache_cooked_write_unsigned (regs, regnum, + current_val + displaced_offset); + /* point the PC back at the non-displaced instruction. */ + regcache_cooked_write_unsigned (regs, gdbarch_pc_regnum (gdbarch), + from + offset); + } /* Handle PC-relative branch instructions. */ - if (opcode == B_INSN || opcode == BC_INSN || opcode == BXL_INSN) + else if (opcode == B_INSN || opcode == BC_INSN || opcode == BXL_INSN) { ULONGEST current_pc; diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index f097a026caf..2c0233d4bfd 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,5 +1,18 @@ 2021-04-12 Will Schmidt + PR gdb/27525 + * gdb/testsuite/gdb.arch/powerpc-addpcis.exp: Testcase harness to + exercise single-stepping over subpcis,lnia,addpcis instructions + with displacement. + * gdb/testsuite/gdb.arch/powerpc-addpcis.s: Testcase with stream + of addpcis/lnia/subpcis instructions. + * gdb/testsuite/gdb.arch/powerpc-lnia.exp: Testcase harness to + exercise single-stepping over lnia instructions with displacement. + * gdb/testsuite/gdb.arch/powerpc-lnia.s: Testcase with stream of + lnia instructions. + +2021-03-31 Will Schmidt + * gdb.arch/powerpc-power10.s: New test for instructions. * gdb.arch/powerpc-power10.exp: Harness to run the test. diff --git a/gdb/testsuite/gdb.arch/powerpc-addpcis.exp b/gdb/testsuite/gdb.arch/powerpc-addpcis.exp new file mode 100644 index 00000000000..d1bc7f49ce6 --- /dev/null +++ b/gdb/testsuite/gdb.arch/powerpc-addpcis.exp @@ -0,0 +1,105 @@ +# Copyright 2021 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + + +# Test to confirm that gdb is properly single stepping over the +# displaced addpcis instruction. +# The addpcis instruction and its extended mnemonics lnia and subpcis +# apply an immediate shifted value (X || 0x0000) to the current PC/NIA +# value, and store that value into the instructions target register. +# When the instruction is displaced, it needs special handling. + +# lnia Rx == addpcis Rx,0 +# subcis Rx,value == addpcis Rx,-value + +if { ![istarget powerpc*-*] } { + verbose "Skipping powerpc addpcis test." + return +} + +set retval 0 + +standard_testfile .s + +if { [prepare_for_testing "failed to prepare" $testfile "$srcfile" \ + {debug quiet}] } { + return -1 +} + +if ![runto_main] then { + return +} + +set check_pc [get_hexadecimal_valueof "\$pc" "default0"] +set bp1 *$check_pc+4 +set bp2 *$check_pc+12 +set bp3 *$check_pc+16 +gdb_breakpoint $bp1 +gdb_breakpoint $bp2 +gdb_breakpoint $bp3 + +gdb_test "stepi" "" "set r3 " +set check_r3 [get_hexadecimal_valueof "\$r3" "default0"] +gdb_test "stepi" "" "set r4" +set check_r4 [get_hexadecimal_valueof "\$r4" "default0"] +gdb_test "stepi" "" "set r5" +set check_r5 [get_hexadecimal_valueof "\$r5" "default0"] +gdb_test "stepi" "" "set r6" +set check_r6 [get_hexadecimal_valueof "\$r6" "default0"] +gdb_test "stepi" "" "set r7" +set check_r7 [get_hexadecimal_valueof "\$r7" "default0"] +gdb_test "stepi" "" "set r8" +set check_r8 [get_hexadecimal_valueof "\$r8" "default0"] +gdb_test "stepi" "" "set r9" +set check_r9 [get_hexadecimal_valueof "\$r9" "default0"] + +# R6 will contain the reference value. All other +# instructions in this test will be storing values +# relative to what is stored in R6. + +# subpcis 3,+0x100 # /* set r3 */ +# subpcis 4,+0x10 # /* set r4 */ +# subpcis 5,+0x1 # /* set r5 */ +# lnia 6 # /* set r6 */ +# addpcis 7,+0x1 # /* set r7 */ +# addpcis 8,+0x10 # /* set r8 */ +# addpcis 9,+0x100 # /* set r9 */ + +if [expr $check_r3 + 0x1000000 != $check_r6 - 0xc ] { + fail "unexpected value r3 + 0x1,000,000 != r6 + 0xc ; r3: $check_r3 r6: $check_r6 " +} +if [expr $check_r4 + 0x100000 != $check_r6 - 0x8 ] { + fail "unexpected value r4 + 0x100,000 != r6 - 0x8 ; r4: $check_r4 r6: $check_r6 " +} +if [expr $check_r5 + 0x10000 != $check_r6 - 0x4 ] { + fail "unexpected value r5 + 0x10,000 != r6 , r5: $check_r5 r6: $check_r6 " +} +if [expr $check_r6 != $check_r6] { + fail "unexpected value r6 != r6 , r6: $check_r6 r6: $check_r6 " +} +if [expr $check_r7 - 0x10000 != $check_r6 + 0x4] { + fail "unexpected value r7 - 0x10,000 != r6 + 0x4 , r7: $check_r7 r7: $check_r6 " +} +if [expr $check_r8 - 0x100000 != $check_r6 + 0x8 ] { + fail "unexpected value r8 - 0x100,000 != r6 , r8: $check_r8 r8: $check_r6 " +} +if [expr $check_r9 - 0x1000000 != $check_r6 + 0xc ] { + fail "unexpected value r9 - 0x1,000,000 != r6 + 0xc , r9: $check_r9 r6: $check_r6 " +} + +gdb_test "info break" +gdb_test "info register r3 r4 r5 r6 r7 r8 r9" +gdb_test "disas main" + diff --git a/gdb/testsuite/gdb.arch/powerpc-addpcis.s b/gdb/testsuite/gdb.arch/powerpc-addpcis.s new file mode 100644 index 00000000000..8a163a23cb3 --- /dev/null +++ b/gdb/testsuite/gdb.arch/powerpc-addpcis.s @@ -0,0 +1,35 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2021 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + + +/* Test to confirm that gdb is properly single stepping over the + displaced addpcis instruction. */ + +.global main +.type main,function +# addpcis: the sum of NIA + ( D || 0x0000) is placed in RT. +main: + subpcis 3,+0x100 # /* set r3 */ + subpcis 4,+0x10 # /* set r4 */ + subpcis 5,+0x1 # /* set r5 */ + lnia 6 # /* set r6 */ + addpcis 7,+0x1 # /* set r7 */ + addpcis 8,+0x10 # /* set r8 */ + addpcis 9,+0x100 # /* set r9 */ + blr + + diff --git a/gdb/testsuite/gdb.arch/powerpc-lnia.exp b/gdb/testsuite/gdb.arch/powerpc-lnia.exp new file mode 100644 index 00000000000..0f56d834046 --- /dev/null +++ b/gdb/testsuite/gdb.arch/powerpc-lnia.exp @@ -0,0 +1,101 @@ +# Copyright 2021 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +# Test to see if gdb is properly single stepping over the +# displaced lnia instruction. This test checks that a series +# of lnia instructions are loading ascending values as expected. + +# lnia is an extended mnemonic for the addpcis instruction, which +# stores the $NIA plus an immediate value into a register. +# +# lnia Rx == addpcis Rx,0 == lnia Rx +# subcis Rx,value == addpcis Rx,-value + +if { ![istarget powerpc*-*] } { + verbose "Skipping powerpc lnia test." + return +} + +set retval 0 + +standard_testfile .s + +if { [prepare_for_testing "failed to prepare" $testfile "$srcfile" \ + {debug quiet}] } { + return -1 +} + +if ![runto_main] then { + return +} + +set before_pc 0 +set check_pc [get_hexadecimal_valueof "\$pc" "default0"] + +# set some breakpoints on the instructions below main(). +set bp1 *$check_pc+4 +set bp2 *$check_pc+12 +set bp3 *$check_pc+16 +gdb_breakpoint $bp1 +gdb_breakpoint $bp2 +gdb_breakpoint $bp3 + +# single-step through the lnia instructions, and retrieve the +# register values as we proceed. +gdb_test "stepi" "" "set r3" +set check_r3 [get_hexadecimal_valueof "\$r3" "default0"] +gdb_test "stepi" "" "set r4" +set check_r4 [get_hexadecimal_valueof "\$r4" "default0"] +gdb_test "stepi" "" "set r5" +set check_r5 [get_hexadecimal_valueof "\$r5" "default0"] +gdb_test "stepi" "" "set r6" +set check_r6 [get_hexadecimal_valueof "\$r6" "default0"] +gdb_test "stepi" "" "set r7" +set check_r7 [get_hexadecimal_valueof "\$r7" "default0"] +gdb_test "stepi" "" "set r8" +set check_r8 [get_hexadecimal_valueof "\$r8" "default0"] +gdb_test "stepi" "" "set r9" +set check_r9 [get_hexadecimal_valueof "\$r9" "default0"] + +# Ensure that our register values are as expected. +# Specifically that the values loaded by the lnia instruction +# reflect the value of the PC as if the instruction was +# not displaced. +if [expr $check_r3 + 4 != $check_r4] { + fail "unexpected value r3+4 != r4 , r3: $check_r3 r4: $check_r4 " +} +if [expr $check_r4 + 4 != $check_r5] { + fail "unexpected value r4+4 != r5 , r4: $check_r4 r5: $check_r5 " +} +if [expr $check_r5 + 4 != $check_r6] { + fail "unexpected value r5+4 != r6 , r5: $check_r5 r6: $check_r6 " +} +if [expr $check_r6 + 4 != $check_r7] { + fail "unexpected value r6+4 != r7 , r6: $check_r6 r7: $check_r7 " +} +if [expr $check_r7 + 4 != $check_r8] { + fail "unexpected value r7+4 != r8 , r7: $check_r7 r8: $check_r8 " +} +if [expr $check_r8 + 4 != $check_r9] { + fail "unexpected value r8+4 != r9 , r8: $check_r8 r9: $check_r9 " +} + +gdb_test "info break" +gdb_test "info register r3 r4 r5 r6 r7 r8 r9" +gdb_test "disas main" + +# Let the inferior store all vector registers in a buffer, then dump +# the buffer and check it. + diff --git a/gdb/testsuite/gdb.arch/powerpc-lnia.s b/gdb/testsuite/gdb.arch/powerpc-lnia.s new file mode 100644 index 00000000000..56e57459121 --- /dev/null +++ b/gdb/testsuite/gdb.arch/powerpc-lnia.s @@ -0,0 +1,33 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2021 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +/* Test to confirm that gdb properly handles lnia instructions + that load the current PC into a target register when executed + from a displaced location. */ + +.global main +.type main,function +main: + lnia 3 # /* set r3 */ + lnia 4 # /* set r4 */ + lnia 5 # /* set r5 */ + lnia 6 # /* set r6 */ + lnia 7 # /* set r7 */ + lnia 8 # /* set r8 */ + lnia 9 # /* set r9 */ + blr + -- 2.30.2