From 8c2999954bd3aa5853f553eb6a050dd38e6d9029 Mon Sep 17 00:00:00 2001 From: Tejas Belagod Date: Thu, 28 Oct 2021 15:44:42 +0100 Subject: [PATCH] arm: add unwinder encoding support for PACBTI This patch adds support for encoding the Return Address Authentication pseudo register - '.save {ra_auth_code}' as defined by the DWARF ABI - in the exception tables where the opcode is defined by the EHABI gas/Changelog: * config/tc-arm.c (arm_reg_type): Add new type REG_TYPE_PSEUDO. (reg_expected_msgs): Add message for pseudo reg type. (reg_list_els): Add new reg list type REGLIST_PSEUDO. (parse_reg_list): Handle new REGLIST_PSEUDO type. (s_arm_unwind_save_pseudo): Encode pseudo reg list save in exception tables. (s_arm_unwind_save): Handle new REG_TYPE_PSEUDO. (reg_names): Add ra_auth_code pseudo register. * testsuite/gas/arm/unwind-pacbti-m.s: New test. * testsuite/gas/arm/unwind-pacbti-m.d: New test. * testsuite/gas/arm/unwind-pacbti-m-readelf.d: New test. --- gas/config/tc-arm.c | 62 +++++++++++++++++++++++++++++++++++---- unwind-pacbti-m-readelf.d | 16 ++++++++++ unwind-pacbti-m.d | 23 +++++++++++++++ unwind-pacbti-m.s | 20 +++++++++++++ 4 files changed, 116 insertions(+), 5 deletions(-) create mode 100644 unwind-pacbti-m-readelf.d create mode 100644 unwind-pacbti-m.d create mode 100644 unwind-pacbti-m.s diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c index f77165513d9..302a18f4a1e 100644 --- a/gas/config/tc-arm.c +++ b/gas/config/tc-arm.c @@ -688,7 +688,8 @@ enum arm_reg_type REG_TYPE_MMXWCG, REG_TYPE_XSCALE, REG_TYPE_RNB, - REG_TYPE_ZR + REG_TYPE_ZR, + REG_TYPE_PSEUDO }; /* Structure for a hash table entry for a register. @@ -733,6 +734,7 @@ const char * const reg_expected_msgs[] = [REG_TYPE_MQ] = N_("MVE vector register expected"), [REG_TYPE_RNB] = "", [REG_TYPE_ZR] = N_("ZR register expected"), + [REG_TYPE_PSEUDO] = N_("Pseudo register expected"), }; /* Some well known registers that we refer to directly elsewhere. */ @@ -1893,6 +1895,7 @@ parse_scalar (char **ccp, int elsize, struct neon_type_el *type, enum enum reg_list_els { REGLIST_RN, + REGLIST_PSEUDO, REGLIST_CLRM, REGLIST_VFP_S, REGLIST_VFP_S_VPR, @@ -1910,7 +1913,8 @@ parse_reg_list (char ** strp, enum reg_list_els etype) long range = 0; int another_range; - gas_assert (etype == REGLIST_RN || etype == REGLIST_CLRM); + gas_assert (etype == REGLIST_RN || etype == REGLIST_CLRM + || etype == REGLIST_PSEUDO); /* We come back here if we get ranges concatenated by '+' or '|'. */ do @@ -1930,8 +1934,14 @@ parse_reg_list (char ** strp, enum reg_list_els etype) int reg; const char apsr_str[] = "apsr"; int apsr_str_len = strlen (apsr_str); + enum arm_reg_type rt; - reg = arm_reg_parse (&str, REG_TYPE_RN); + if (etype == REGLIST_RN || etype == REGLIST_CLRM) + rt = REG_TYPE_RN; + else + rt = REG_TYPE_PSEUDO; + + reg = arm_reg_parse (&str, rt); if (etype == REGLIST_CLRM) { if (reg == REG_SP || reg == REG_PC) @@ -1950,6 +1960,14 @@ parse_reg_list (char ** strp, enum reg_list_els etype) return FAIL; } } + else if (etype == REGLIST_PSEUDO) + { + if (reg == FAIL) + { + first_error (_(reg_expected_msgs[REG_TYPE_PSEUDO])); + return FAIL; + } + } else /* etype == REGLIST_RN. */ { if (reg == FAIL) @@ -4258,6 +4276,32 @@ s_arm_unwind_personality (int ignored ATTRIBUTE_UNUSED) demand_empty_rest_of_line (); } +/* Parse a directive saving pseudo registers. */ + +static void +s_arm_unwind_save_pseudo (void) +{ + valueT op; + long range; + + range = parse_reg_list (&input_line_pointer, REGLIST_PSEUDO); + if (range == FAIL) + { + as_bad (_("expected pseudo register list")); + ignore_rest_of_line (); + return; + } + + demand_empty_rest_of_line (); + + if (range & (1 << 9)) + { + /* Opcode for restoring RA_AUTH_CODE. */ + op = 0xb4; + add_unwind_opcode (op, 1); + } +} + /* Parse a directive saving core registers. */ @@ -4725,6 +4769,10 @@ s_arm_unwind_save (int arch_v6) s_arm_unwind_save_core (); return; + case REG_TYPE_PSEUDO: + s_arm_unwind_save_pseudo (); + return; + case REG_TYPE_VFD: if (arch_v6) s_arm_unwind_save_vfp_armv6 (); @@ -23915,8 +23963,12 @@ static const struct reg_entry reg_names[] = /* XScale accumulator registers. */ REGNUM(acc,0,XSCALE), REGNUM(ACC,0,XSCALE), - /* Alias 'ra_auth_code' to r12 for pacbti. */ - REGDEF(ra_auth_code,12,RN), + /* DWARF ABI defines RA_AUTH_CODE to 143. It also reserves 134-142 for future + expansion. RA_AUTH_CODE here is given the value 143 % 134 to make it easy + for tc_arm_regname_to_dw2regnum to translate to DWARF reg number using + 134 + reg_number should the range 134 to 142 be used for more pseudo regs + in the future. This also helps fit RA_AUTH_CODE into a bitmask. */ + REGDEF(ra_auth_code,9,PSEUDO), }; #undef REGDEF #undef REGNUM diff --git a/unwind-pacbti-m-readelf.d b/unwind-pacbti-m-readelf.d new file mode 100644 index 00000000000..ba1d76dd18f --- /dev/null +++ b/unwind-pacbti-m-readelf.d @@ -0,0 +1,16 @@ +#readelf: -u +#source: unwind-pacbti-m.s +#name: Unwind table information for Armv8.1-M.Mainline PACBTI extension +# This test is only valid on ELF based ports. +#notarget: *-*-pe *-*-wince +# VxWorks needs a special variant of this file. +#skip: *-*-vxworks* + +Unwind section '.ARM.exidx' at offset 0x40 contains 1 entry: + +0x0 : 0x80b4a8b0 + Compact model index: 0 + 0xb4 pop {ra_auth_code} + 0xa8 pop {r4, r14} + 0xb0 finish + diff --git a/unwind-pacbti-m.d b/unwind-pacbti-m.d new file mode 100644 index 00000000000..584b12037b3 --- /dev/null +++ b/unwind-pacbti-m.d @@ -0,0 +1,23 @@ +#objdump: -sr +#name: Unwind information for Armv8.1-M.Mainline PACBTI extension +# This test is only valid on ELF based ports. +#notarget: *-*-pe *-*-wince +# VxWorks needs a special variant of this file. +#skip: *-*-vxworks* + +.*: file format.* + +RELOCATION RECORDS FOR \[.ARM.exidx\]: +OFFSET TYPE VALUE +00000000 R_ARM_PREL31 .text +00000000 R_ARM_NONE __aeabi_unwind_cpp_pr0 + + +Contents of section .text: + 0000 10b54df8 04cd5df8 04cb10bd .* +Contents of section .ARM.exidx: + 0000 00000000 b0a8b480 .* +Contents of section .ARM.attributes: + 0000 41290000 00616561 62690001 1f000000 .* + 0010 05382e31 2d4d2e4d 41494e00 0615074d .* + 0020 09033202 34024a01 4c01 .* diff --git a/unwind-pacbti-m.s b/unwind-pacbti-m.s new file mode 100644 index 00000000000..5a6ea2eec2b --- /dev/null +++ b/unwind-pacbti-m.s @@ -0,0 +1,20 @@ + + .arch armv8.1-m.main + .arch_extension pacbti + .eabi_attribute 50, 2 + .eabi_attribute 52, 2 + .eabi_attribute 74, 1 + .eabi_attribute 76, 1 + .text + .syntax unified + .thumb + .thumb_func +foo: + .fnstart + push {r4, lr} + .save {r4, lr} + push {r12} + .save {ra_auth_code} + pop {r12} + pop {r4, pc} + .fnend -- 2.30.2