From: Ezra Sitorus Date: Mon, 1 Jun 2026 22:36:46 +0000 (+0100) Subject: gdb/aarch64: record/replay support for LRCPC3 X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=ec6bbd2e0cb4d141db9048b0b5d5c0bcaa66c284;p=thirdparty%2Fbinutils-gdb.git gdb/aarch64: record/replay support for LRCPC3 FEAT_LRCPC3 introduces various load/store instructions with release consistency for cases where ordering is required. This patch teaches GDB to decode these instructions for recording and reversing. The gdb.reverse/aarch64-lrcpc3.exp testcase verifies that the instructions are recorded and correctly reversed. In particular, there are some interesting cases to note: * ldapur/stlur are SIMD instructions, but are not decoded in the simd function. * There are writeback cases to cover too. These were taken from the binutils testcases: gas/testsuite/gas/aarch64/rcpc3.s. The full testsuite was done on aarch64-none-linux-gnu without LRCPC3. The gdb.arch and gdb.reverse tests were run on Shrinkwrap with LRCPC3 support. Please note: 1) There is no support for LRCPC and LRCPC2 instructions 2) LRCPC3 is gated with +rcpc3 in GCC/binutils and LLVM. Approved-by: Thiago Jung Bauermann --- diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c index 673815c2763..0cce4072ac7 100644 --- a/gdb/aarch64-tdep.c +++ b/gdb/aarch64-tdep.c @@ -5812,6 +5812,93 @@ aarch64_record_load_store (aarch64_insn_decode_record *aarch64_insn_r) aarch64_insn_r->reg_rec_count = 1; } } + /* LRCPC3 instructions. This covers ldiapp/stilp, ldapur/stlur (FP/SIMD), + ldapr/stlr. */ + else if ((insn_bits24_27 & 0x0b) == 0x09 && insn_bits28_29 == 0x01 + && insn_bits10_11 == 0x02 && !insn_bit21) + { + /* ldapur/stlur (FP/SIMD), ldapr/stlr. We can differentiate between the + 2 types by checking the vector flag. */ + if (insn_bit23 || vector_flag) + { + /* For the vector instruction, the offset comes from the imm9 + bitfield, whereas the other can only take possible values from the + size bitfield. */ + int16_t imm9_off = sbits (aarch64_insn_r->aarch64_insn, 12, 20); + offset = vector_flag ? imm9_off : -(1 << size_bits); + uint32_t regnum_offset = vector_flag ? AARCH64_V0_REGNUM : 0; + if (ld_flag) + { + record_buf[0] = reg_rt + regnum_offset; + aarch64_insn_r->reg_rec_count = 1; + if (!vector_flag) + { + /* The Rn register always has writeback in LRCPC3. This is + not the case in LRCPC. */ + record_buf[1] = reg_rn; + aarch64_insn_r->reg_rec_count = 2; + } + } + else + { + regcache_raw_read_unsigned (aarch64_insn_r->regcache, reg_rn, + &address); + /* (vector_flag && insn_bit23) is the STLUR instruction with Q + register. */ + datasize = (vector_flag && insn_bit23) ? 128 : (8 << size_bits); + /* LRCPC3 adds STLR with a pre-indexed offset. There is another + STLR variant without offset but this has a different encoding. */ + if (!vector_flag) + { + record_buf[0] = reg_rn; + aarch64_insn_r->reg_rec_count = 1; + } + record_buf_mem[0] = datasize >> 3; + record_buf_mem[1] = address + offset; + aarch64_insn_r->mem_rec_count = 1; + } + } + else + { + /* ldiapp/stilp. */ + uint8_t opc2 = bits (aarch64_insn_r->aarch64_insn, 12, 15); + reg_rt2 = bits (aarch64_insn_r->aarch64_insn, 16, 20); + if (ld_flag) + { + record_buf[0] = reg_rt; + record_buf[1] = reg_rt2; + aarch64_insn_r->reg_rec_count = 2; + + /* If the registers don't match and there's no offset then + there's WB. */ + if (reg_rn != reg_rt && reg_rn != reg_rt2 && opc2 == 0) + { + record_buf[2] = reg_rn; + aarch64_insn_r->reg_rec_count = 3; + } + } + else + { + datasize = 8 << size_bits; + regcache_raw_read_unsigned (aarch64_insn_r->regcache, reg_rn, + &address); + offset = (opc2 == 0) ? (2 << size_bits) : 0; + address -= offset; + + record_buf_mem[0] = datasize >> 3; + record_buf_mem[1] = address; + record_buf_mem[2] = datasize >> 3; + record_buf_mem[3] = address + (datasize >> 3); + aarch64_insn_r->mem_rec_count = 2; + + if (offset != 0) + { + record_buf[0] = reg_rn; + aarch64_insn_r->reg_rec_count = 1; + } + } + } + } /* Load/store register (register offset) instructions. */ else if ((insn_bits24_27 & 0x0b) == 0x08 && insn_bits28_29 == 0x03 && insn_bits10_11 == 0x02 && insn_bit21) diff --git a/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.c b/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.c new file mode 100644 index 00000000000..d61d32396e4 --- /dev/null +++ b/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.c @@ -0,0 +1,216 @@ +/* This test program is part of GDB, the GNU debugger. + + Copyright 2024-2026 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 . */ + +#include +#include +#include + +#define INITIAL_STRING "This is just some string." +#define BUF_SIZE sizeof (INITIAL_STRING) + +#define PREPARE_SRC_AND_PTR(OFFSET) \ + strcpy (src, INITIAL_STRING); \ + __asm__ volatile ("mov x21, %0" \ + : \ + : "r"((uint64_t *)((uint8_t *)src + (OFFSET))) \ + : "x21") + +#define PREPARE_GPR(OFFSET) \ + __asm__ volatile ("mov x19, #0\n" ::: "x19"); \ + __asm__ volatile ("mov x20, #0\n" ::: "x20"); \ + PREPARE_SRC_AND_PTR (OFFSET) + +#define PREPARE_VECTOR_REG(OFFSET) \ + __asm__ volatile ("movi v22.2d, #0\n" ::: "v22"); \ + PREPARE_SRC_AND_PTR (OFFSET) + +int +main (void) +{ + alignas (16) char src[BUF_SIZE]; + + PREPARE_GPR (0); + /* Before ldiapp-0. */ + __asm__ volatile ("ldiapp x19, x20, [x21]\n" : : : "x19", "x20", "memory"); + /* After ldiapp-0. */ + + PREPARE_GPR (0); + /* Before ldiapp-1. */ + __asm__ volatile ("ldiapp w19, w20, [x21]\n" : : : "x19", "x20", "memory"); + /* After ldiapp-1. */ + + PREPARE_GPR (0); + /* Before ldiapp-2. */ + __asm__ volatile ("ldiapp x19, x20, [x21], #16\n" + : + : + : "x19", "x20", "x21", "memory"); + /* After ldiapp-2. */ + + PREPARE_GPR (0); + /* Before ldiapp-3. */ + __asm__ volatile ("ldiapp w19, w20, [x21], #8\n" + : + : + : "x19", "x20", "x21", "memory"); + /* After ldiapp-3. */ + /* Register overlap between source and destination registers. Since there is + no offset, writeback is disabled. */ + + PREPARE_GPR (0); + /* Before ldiapp-4. */ + __asm__ volatile ("ldiapp x21, x20, [x21]\n" : : : "x20", "x21", "memory"); + /* After ldiapp-4. */ + + PREPARE_GPR (0); + /* Before ldiapp-5. */ + __asm__ volatile ("ldiapp w21, w20, [x21]\n" : : : "x20", "x21", "memory"); + /* After ldiapp-5. */ + + PREPARE_GPR (0); + /* Before stilp-0. */ + __asm__ volatile ("stilp x19, x20, [x21]\n" : : : "memory"); + /* After stilp-0. */ + + PREPARE_GPR (0); + /* Before stilp-1. */ + __asm__ volatile ("stilp w19, w20, [x21]\n" : : : "memory"); + /* After stilp-1. */ + + PREPARE_GPR (16); + /* Before stilp-2. */ + __asm__ volatile ("stilp x19, x20, [x21, #-16]!\n" : : : "x21", "memory"); + /* After stilp-2. */ + + PREPARE_GPR (8); + /* Before stilp-3. */ + __asm__ volatile ("stilp w19, w20, [x21, #-8]!\n" : : : "x21", "memory"); + /* After stilp-3. */ + /* Register overlap. Since there is no offset, writeback is disabled. */ + + PREPARE_GPR (0); + /* Before stilp-4. */ + __asm__ volatile ("stilp x21, x20, [x21]\n" : : : "memory"); + /* After stilp-4. */ + + PREPARE_GPR (0); + /* Before stilp-5. */ + __asm__ volatile ("stilp w21, w20, [x21]\n" : : : "memory"); + /* After stilp-5. */ + + PREPARE_GPR (0); + /* Before ldapr-0. */ + __asm__ volatile ("ldapr x19, [x21], #8\n" : : : "x19", "x21", "memory"); + /* After ldapr-0. */ + + PREPARE_GPR (0); + /* Before ldapr-1. */ + __asm__ volatile ("ldapr w19, [x21], #4\n" : : : "x19", "x21", "memory"); + /* After ldapr-1. */ + + PREPARE_GPR (8); + /* Before stlr-0. */ + __asm__ volatile ("stlr x19, [x21, #-8]!\n" : : : "x21", "memory"); + /* After stlr-0. */ + + PREPARE_GPR (4); + /* Before stlr-1. */ + __asm__ volatile ("stlr w19, [x21, #-4]!\n" : : : "x21", "memory"); + /* After stlr-1. */ + + PREPARE_VECTOR_REG (0); + /* Before ldap1-0. */ + __asm__ volatile ("ldap1 {v22.d}[0], [x21]\n" : : : "v22", "memory"); + /* After ldap1-0. */ + + PREPARE_VECTOR_REG (0); + /* Before stl1-0. */ + __asm__ volatile ("stl1 {v22.d}[0], [x21]\n" : : : "memory"); + /* After stl1-0. */ + + PREPARE_VECTOR_REG (0); + /* Before ldapur-0. */ + __asm__ volatile ("ldapur d22, [x21]\n" : : : "v22", "memory"); + /* After ldapur-0. */ + + PREPARE_VECTOR_REG (0); + /* Before stlur-0. */ + __asm__ volatile ("stlur d22, [x21]\n" : : : "memory"); + /* After stlur-0. */ + + PREPARE_VECTOR_REG (256); + /* Before ldapur-1. */ + __asm__ volatile ("ldapur d22, [x21, #-256]\n" : : : "v22", "memory"); + /* After ldapur-1. */ + + PREPARE_VECTOR_REG (256); + /* Before stlur-1. */ + __asm__ volatile ("stlur d22, [x21, #-256]\n" : : : "memory"); + /* After stlur-1. */ + + PREPARE_VECTOR_REG (-255); + /* Before ldapur-2. */ + __asm__ volatile ("ldapur d22, [x21, #255]\n" : : : "v22", "memory"); + /* After ldapur-2. */ + + PREPARE_VECTOR_REG (-255); + /* Before stlur-2. */ + __asm__ volatile ("stlur d22, [x21, #255]\n" : : : "memory"); + /* After stlur-2. */ + + PREPARE_VECTOR_REG (0); + /* Before ldapur-3. */ + __asm__ volatile ("ldapur h22, [x21]\n" : : : "v22", "memory"); + /* After ldapur-3. */ + + PREPARE_VECTOR_REG (0); + /* Before stlur-3. */ + __asm__ volatile ("stlur h22, [x21]\n" : : : "memory"); + /* After stlur-3. */ + + PREPARE_VECTOR_REG (0); + /* Before ldapur-4. */ + __asm__ volatile ("ldapur s22, [x21]\n" : : : "v22", "memory"); + /* After ldapur-4. */ + + PREPARE_VECTOR_REG (0); + /* Before stlur-4. */ + __asm__ volatile ("stlur s22, [x21]\n" : : : "memory"); + /* After stlur-4. */ + + PREPARE_VECTOR_REG (0); + /* Before ldapur-5. */ + __asm__ volatile ("ldapur d22, [x21]\n" : : : "v22", "memory"); + /* After ldapur-5. */ + + PREPARE_VECTOR_REG (0); + /* Before stlur-5. */ + __asm__ volatile ("stlur d22, [x21]\n" : : : "memory"); + /* After stlur-5. */ + + PREPARE_VECTOR_REG (0); + /* Before ldapur-6. */ + __asm__ volatile ("ldapur q22, [x21]\n" : : : "v22", "memory"); + /* After ldapur-6. */ + + PREPARE_VECTOR_REG (0); + /* Before stlur-6. */ + __asm__ volatile ("stlur q22, [x21]\n" : : : "memory"); + /* After stlur-6. */ + + return 0; +} diff --git a/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.exp b/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.exp new file mode 100644 index 00000000000..b9e48147c2a --- /dev/null +++ b/gdb/testsuite/gdb.reverse/aarch64-lrcpc3.exp @@ -0,0 +1,190 @@ +# Copyright 2024-2026 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 instruction record for AArch64 FEAT_LRCPC3 instructions. +# Based on gdb.reverse/aarch64-mops.exp +# +# The basic flow of the record tests are: +# 1) Stop before executing the instructions of interest. Record +# the initial value of the registers that the instruction will +# change, i.e. the destination register. +# 2) Execute the instructions. Record the new value of the +# registers that changed. +# 3) Reverse the direction of the execution and execute back to +# just before the instructions of interest. Record the final +# value of the registers of interest. +# 4) Check that the initial and new values of the registers are +# different, i.e. the instruction changed the registers as expected. +# 5) Check that the initial and final values of the registers are +# the same, i.e. GDB record restored the registers to their +# original values. + +require allow_aarch64_lrcpc3_tests + +standard_testfile + +if {[prepare_for_testing "failed to prepare" ${testfile} ${srcfile} \ + [list debug additional_flags=-march=armv8-a+rcpc3]]} { + return +} + +if {![runto_main]} { + return +} + +gdb_test_no_output "record full" + +proc test_single_asm {name diff_reg diff_mem same_reg same_mem} { + with_test_prefix $name { + + set before_seq [gdb_get_line_number "Before ${name}"] + set after_seq [gdb_get_line_number "After ${name}"] + + set insn [lindex [split $name "-"] 0] + + gdb_test "break $before_seq" \ + "Breakpoint ${::decimal} at ${::hex}: file .*/aarch64-lrcpc3.c, line ${::decimal}\\." \ + "$insn before instruction sequence" + + gdb_continue_to_breakpoint "about to execute instruction sequence" \ + [multi_line ".*/aarch64-lrcpc3.c:${::decimal}" \ + "${::decimal}\[ \t\]+__asm__ volatile \\(\"${insn} .*\".*"] + + # Depending on the compiler, the line number information may put GDB a few + # instructions before the beginning of the asm statement. + arrive_at_instruction $insn + # Add a breakpoint that we're sure is at the prologue instruction. + gdb_test "break *\$pc" \ + "Breakpoint ${::decimal} at ${::hex}: file .*/aarch64-lrcpc3.c, line ${::decimal}\\." \ + "break at prologue instruction" + + # Record the initial memory and register values. + set regs [concat $diff_reg $same_reg] + set mem [concat $diff_mem $same_mem] + foreach r $regs { + set ${r}_initial [capture_command_output "info register $r" ""] + } + foreach m $mem { + set ${m}_initial [capture_command_output "x/x $m" ""] + } + + gdb_test "break $after_seq" \ + "Breakpoint ${::decimal} at ${::hex}: file .*/aarch64-lrcpc3.c, line ${::decimal}\\." \ + "$insn after instruction sequence" + gdb_continue_to_breakpoint "executed instruction sequence" \ + [multi_line ".*/aarch64-lrcpc3.c:${::decimal}" ".*"] + + # Record the new memory and register values. + foreach r $regs { + set ${r}_new [capture_command_output "info register $r" ""] + } + foreach m $mem { + set ${m}_new [capture_command_output "x/x $m" ""] + } + + # Execute in reverse to before the instruction sequence. + gdb_test_no_output "set exec-direction reverse" + + gdb_continue_to_breakpoint "reversed execution of instruction sequence" \ + [multi_line ".*/aarch64-lrcpc3.c:${::decimal}" \ + "${::decimal}\[ \t\]+__asm__ volatile \\(\"${insn} .*\".*"] + + # Record the final memory and register values. + foreach r $regs { + set ${r}_final [capture_command_output "info register $r" ""] + } + foreach m $mem { + set ${m}_final [capture_command_output "x/x $m" ""] + } + + foreach v [concat $same_reg $same_mem] { + gdb_assert ![string compare [set ${v}_initial] [set ${v}_new]] \ + "check $v initial value versus $v new value" + gdb_assert ![string compare [set ${v}_initial] [set ${v}_final]] \ + "check $v initial value versus $v final value" + } + + foreach v [concat $diff_reg $diff_mem] { + gdb_assert [string compare [set ${v}_initial] [set ${v}_new]] \ + "check $v initial value versus $v new value" + gdb_assert ![string compare [set ${v}_initial] [set ${v}_final]] \ + "check $v initial value versus $v final value" + } + + # Restore forward execution and go to end of recording. + gdb_test_no_output "set exec-direction forward" + gdb_test "record goto end" \ + [multi_line \ + "Go forward to insn number ${::decimal}" \ + "#0 main \\(\\) at .*/aarch64-lrcpc3.c:${::decimal}" \ + ".*"] + } +} + +set ldiapp_cases { + { ldiapp-0 { x19 x20 } { } { x21 } { src } } + { ldiapp-1 { w19 w20 } { } { x21 } { src } } + { ldiapp-2 { x19 x20 x21 } { } { } { src } } + { ldiapp-3 { w19 w20 x21 } { } { } { src } } + { ldiapp-4 { x21 x20 } { } { } { src } } + { ldiapp-5 { w21 w20 } { } { } { src } } +} + +set stilp_cases { + { stilp-0 { } { src } { x19 x20 x21 } { } } + { stilp-1 { } { src } { w19 w20 x21 } { } } + { stilp-2 { x21 } { src } { x19 x20 } { } } + { stilp-3 { x21 } { src } { x19 x20 } { } } + { stilp-4 { } { src } { x20 x21 } { } } + { stilp-5 { } { src } { w20 x21 } { } } +} + +set ldapr_stlr_cases { + { ldapr-0 { x19 x21 } { } { } { src } } + { ldapr-1 { w19 x21 } { } { } { src } } + { stlr-0 { x21 } { src } { x19 } { } } + { stlr-1 { x21 } { src } { w19 } { } } +} + +set ldap1_stl1_cases { + { ldap1-0 { v22 } { } { x21 } { src } } + { stl1-0 { } { src } { v22 } { } } +} + +set ldapur_stlur_cases { + { ldapur-0 { v22 } { } { x21 } { src } } + { stlur-0 { } { src } { x21 v22 } { } } + { ldapur-1 { v22 } { } { x21 } { src } } + { stlur-1 { } { src } { x21 v22 } { } } + { ldapur-2 { v22 } { } { x21 } { src } } + { stlur-2 { } { src } { x21 v22 } { } } + { ldapur-3 { v22 } { } { x21 } { src } } + { stlur-3 { } { src } { x21 v22 } { } } + { ldapur-4 { v22 } { } { x21 } { src } } + { stlur-4 { } { src } { x21 v22 } { } } + { ldapur-5 { v22 } { } { x21 } { src } } + { stlur-5 { } { src } { x21 v22 } { } } + { ldapur-6 { v22 } { } { x21 } { src } } + { stlur-6 { } { src } { x21 v22 } { } } +} + +set all_cases [concat \ + $ldiapp_cases $stilp_cases $ldapr_stlr_cases \ + $ldap1_stl1_cases $ldapur_stlur_cases] + +foreach c $all_cases { + lassign $c name diff_reg diff_mem same_reg same_mem + test_single_asm $name $diff_reg $diff_mem $same_reg $same_mem +} diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp index 96ef9e952a8..c87876664f0 100644 --- a/gdb/testsuite/lib/gdb.exp +++ b/gdb/testsuite/lib/gdb.exp @@ -5332,6 +5332,65 @@ gdb_caching_proc allow_aarch64_fpmr_tests {} { return $allow_fpmr_tests } +# Run a test on the target to see if it supports AArch64 LRCPC3 (Load-Acquire +# RCpc instructions) extensions. Return 1 if so, 0 if it does not. Note this +# causes a restart of GDB. + +gdb_caching_proc allow_aarch64_lrcpc3_tests {} { + global srcdir subdir gdb_prompt inferior_exited_re + + set me "allow_aarch64_lrcpc3_tests" + + if { ![is_aarch64_target] } { + return 0 + } + + # Take the opportunity to check whether the toolchain knows about LRCPC3. + set compile_flags "{additional_flags=-march=armv8-a+rcpc3}" + + # Compile a program that tests the LRCPC3 feature. + set src { + #include + #include + + /* Feature check for LRCPC3. */ + #ifndef HWCAP2_LRCPC3 + #define HWCAP2_LRCPC3 (1ULL << 46) + #endif + + int main (void) { + bool lrcpc3_supported = getauxval (AT_HWCAP2) & HWCAP2_LRCPC3; + + /* Return success if LRCPC3 is supported. */ + return !lrcpc3_supported; + } + } + + if {![gdb_simple_compile $me $src executable $compile_flags]} { + return 0 + } + + # Compilation succeeded so now run it via gdb. + clean_restart + gdb_load $obj + gdb_run_cmd + gdb_expect { + -re ".*$inferior_exited_re normally.*${gdb_prompt} $" { + verbose -log "\n$me: lrcpc3 support detected" + set allow_lrcpc3_tests 1 + } + -re ".*$inferior_exited_re with code 01.*${gdb_prompt} $" { + verbose -log "\n$me: lrcpc3 support not detected" + set allow_lrcpc3_tests 0 + } + } + gdb_exit + remote_file build delete $obj + + verbose "$me: returning $allow_lrcpc3_tests" 2 + return $allow_lrcpc3_tests +} + # Run a test on the target to see if it supports the AArch64 CSSC feature. # Return 1 if so, 0 if it does not. Note this causes a restart of GDB.