From 5add3fce49f1c36a47651238fb0b0592a04d645e Mon Sep 17 00:00:00 2001 From: Luis Machado Date: Thu, 2 Feb 2023 14:00:58 +0000 Subject: [PATCH] sme: Fixup sigframe gdbarch when vg/svg changes With SME, where you have two different vector lengths (vl and svl), it may be the case that the current frame has a set of vector lengths (A) but the signal context has a distinct set of vector lengths (B). In this case, we may run into a situation where GDB attempts to use a gdbarch created for set A, but it is really dealing with a frame that was using set B. This is problematic, specially with SME, because now we have a different number of pseudo-registers and types that gets cached on creation of each gdbarch variation. For AArch64 we really need to be able to use the correct gdbarch for each frame, and I noticed the signal frame (tramp-frame) doesn't have a settable prev_arch field. So it ends up using the default frame_unwind_arch function and eventually calling get_frame_arch (next_frame). That means the previous frame will always have the same gdbarch as the current frame. This patch first refactors the AArch64/Linux signal context code, simplifying it and making it reusable for our purposes of calculating the previous frame's gdbarch. I introduced a struct that holds information that we have found in the signal context, and with which we can make various decisions. Finally, a small change to tramp-frame.c and tramp-frame.h to expose a prev_arch hook that the architecture can set. With this new field, AArch64/Linux can implement a hook that looks at the signal context and infers the gdbarch for the previous frame. Regression-tested on aarch64-linux Ubuntu 22.04/20.04. Approved-By: Simon Marchi Reviewed-by: Thiago Jung Bauermann --- gdb/aarch64-linux-tdep.c | 278 +++++++++++++++++++++++++++------------ gdb/tramp-frame.c | 1 + gdb/tramp-frame.h | 5 + 3 files changed, 198 insertions(+), 86 deletions(-) diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c index f76d1888072..39855844ad0 100644 --- a/gdb/aarch64-linux-tdep.c +++ b/gdb/aarch64-linux-tdep.c @@ -184,6 +184,39 @@ #define AARCH64_SME_CONTEXT_SIZE(svq) \ (AARCH64_SME_CONTEXT_REGS_OFFSET + AARCH64_SME_CONTEXT_ZA_SIZE (svq)) +/* Holds information about the signal frame. */ +struct aarch64_linux_sigframe +{ + /* The stack pointer value. */ + CORE_ADDR sp = 0; + /* The sigcontext address. */ + CORE_ADDR sigcontext_address = 0; + /* The start/end signal frame section addresses. */ + CORE_ADDR section = 0; + CORE_ADDR section_end = 0; + + /* Starting address of the section containing the general purpose + registers. */ + CORE_ADDR gpr_section = 0; + /* Starting address of the section containing the FPSIMD registers. */ + CORE_ADDR fpsimd_section = 0; + /* Starting address of the section containing the SVE registers. */ + CORE_ADDR sve_section = 0; + /* Starting address of the section containing the ZA register. */ + CORE_ADDR za_section = 0; + /* Starting address of the section containing extra information. */ + CORE_ADDR extra_section = 0; + + /* The vector length (SVE or SSVE). */ + ULONGEST vl = 0; + /* The streaming vector length (SSVE/ZA). */ + ULONGEST svl = 0; + /* True if we are in streaming mode, false otherwise. */ + bool streaming_mode = false; + /* True if we have a ZA payload, false otherwise. */ + bool za_payload = false; +}; + /* Read an aarch64_ctx, returning the magic value, and setting *SIZE to the size, or return 0 on error. */ @@ -318,129 +351,115 @@ aarch64_linux_restore_vregs (struct gdbarch *gdbarch, } } -/* Implement the "init" method of struct tramp_frame. */ +/* Given a signal frame THIS_FRAME, read the signal frame information into + SIGNAL_FRAME. */ static void -aarch64_linux_sigframe_init (const struct tramp_frame *self, - frame_info_ptr this_frame, - struct trad_frame_cache *this_cache, - CORE_ADDR func) +aarch64_linux_read_signal_frame_info (frame_info_ptr this_frame, + struct aarch64_linux_sigframe &signal_frame) { - struct gdbarch *gdbarch = get_frame_arch (this_frame); - enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); - aarch64_gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); - CORE_ADDR sp = get_frame_register_unsigned (this_frame, AARCH64_SP_REGNUM); - CORE_ADDR sigcontext_addr = (sp + AARCH64_RT_SIGFRAME_UCONTEXT_OFFSET - + AARCH64_UCONTEXT_SIGCONTEXT_OFFSET ); - CORE_ADDR section = sigcontext_addr + AARCH64_SIGCONTEXT_RESERVED_OFFSET; - CORE_ADDR section_end = section + AARCH64_SIGCONTEXT_RESERVED_SIZE; - CORE_ADDR fpsimd = 0; - CORE_ADDR sve_regs = 0; - CORE_ADDR za_state = 0; - uint64_t svcr = 0; + signal_frame.sp = get_frame_register_unsigned (this_frame, AARCH64_SP_REGNUM); + signal_frame.sigcontext_address + = signal_frame.sp + AARCH64_RT_SIGFRAME_UCONTEXT_OFFSET + + AARCH64_UCONTEXT_SIGCONTEXT_OFFSET; + signal_frame.section + = signal_frame.sigcontext_address + AARCH64_SIGCONTEXT_RESERVED_OFFSET; + signal_frame.section_end + = signal_frame.section + AARCH64_SIGCONTEXT_RESERVED_SIZE; + + signal_frame.gpr_section + = signal_frame.sigcontext_address + AARCH64_SIGCONTEXT_XO_OFFSET; + + /* Search for all the other sections, stopping at null. */ + CORE_ADDR section = signal_frame.section; + CORE_ADDR section_end = signal_frame.section_end; uint32_t size, magic; - size_t vq = 0, svq = 0; bool extra_found = false; - int num_regs = gdbarch_num_regs (gdbarch); - - /* Read in the integer registers. */ + enum bfd_endian byte_order + = gdbarch_byte_order (get_frame_arch (this_frame)); - for (int i = 0; i < 31; i++) - { - trad_frame_set_reg_addr (this_cache, - AARCH64_X0_REGNUM + i, - sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET - + i * AARCH64_SIGCONTEXT_REG_SIZE); - } - trad_frame_set_reg_addr (this_cache, AARCH64_SP_REGNUM, - sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET - + 31 * AARCH64_SIGCONTEXT_REG_SIZE); - trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM, - sigcontext_addr + AARCH64_SIGCONTEXT_XO_OFFSET - + 32 * AARCH64_SIGCONTEXT_REG_SIZE); - - /* Search for the FP and SVE sections, stopping at null. */ while ((magic = read_aarch64_ctx (section, byte_order, &size)) != 0 && size != 0) { switch (magic) { case AARCH64_FPSIMD_MAGIC: - fpsimd = section; - section += size; - break; + { + signal_frame.fpsimd_section = section; + section += size; + break; + } case AARCH64_SVE_MAGIC: { /* Check if the section is followed by a full SVE dump, and set sve_regs if it is. */ gdb_byte buf[4]; - uint16_t flags; - - if (!tdep->has_sve ()) - break; + /* Extract the vector length. */ if (target_read_memory (section + AARCH64_SVE_CONTEXT_VL_OFFSET, buf, 2) != 0) { + warning (_("Failed to read the vector length from the SVE " + "signal frame context.")); section += size; break; } - vq = sve_vq_from_vl (extract_unsigned_integer (buf, 2, byte_order)); - /* If SME is supported, also read the flags field. It may - indicate if this SVE context is for streaming mode (SSVE). */ - if (tdep->has_sme ()) + signal_frame.vl = extract_unsigned_integer (buf, 2, byte_order); + + /* Extract the flags to check if we are in streaming mode. */ + if (target_read_memory (section + + AARCH64_SVE_CONTEXT_FLAGS_OFFSET, + buf, 2) != 0) { - if (target_read_memory (section - + AARCH64_SVE_CONTEXT_FLAGS_OFFSET, - buf, 2) != 0) - { - section += size; - break; - } - flags = extract_unsigned_integer (buf, 2, byte_order); - - /* Is this SSVE data? If so, enable the SM bit in SVCR. */ - if (flags & SVE_SIG_FLAG_SM) - svcr |= SVCR_SM_BIT; + warning (_("Failed to read the flags from the SVE signal frame" + " context.")); + section += size; + break; } - if (size >= AARCH64_SVE_CONTEXT_SIZE (vq)) - sve_regs = section + AARCH64_SVE_CONTEXT_REGS_OFFSET; + uint16_t flags = extract_unsigned_integer (buf, 2, byte_order); + /* Is this SSVE data? If so, we are in streaming mode. */ + signal_frame.streaming_mode + = (flags & SVE_SIG_FLAG_SM) ? true : false; + + ULONGEST vq = sve_vq_from_vl (signal_frame.vl); + if (size >= AARCH64_SVE_CONTEXT_SIZE (vq)) + { + signal_frame.sve_section + = section + AARCH64_SVE_CONTEXT_REGS_OFFSET; + } section += size; break; } case AARCH64_ZA_MAGIC: { - if (!tdep->has_sme ()) - { - section += size; - break; - } - /* Check if the section is followed by a full ZA dump, and set za_state if it is. */ gdb_byte buf[2]; + /* Extract the streaming vector length. */ if (target_read_memory (section + AARCH64_SME_CONTEXT_SVL_OFFSET, buf, 2) != 0) { + warning (_("Failed to read the streaming vector length from " + "ZA signal frame context.")); section += size; break; } - svq = sve_vq_from_vl (extract_unsigned_integer (buf, 2, - byte_order)); + + signal_frame.svl = extract_unsigned_integer (buf, 2, byte_order); + ULONGEST svq = sve_vq_from_vl (signal_frame.svl); if (size >= AARCH64_SME_CONTEXT_SIZE (svq)) { - za_state = section + AARCH64_SME_CONTEXT_REGS_OFFSET; - /* We have ZA data. Enable the ZA bit in SVCR. */ - svcr |= SVCR_ZA_BIT; + signal_frame.za_section + = section + AARCH64_SME_CONTEXT_REGS_OFFSET; + signal_frame.za_payload = true; } - section += size; break; } @@ -456,11 +475,14 @@ aarch64_linux_sigframe_init (const struct tramp_frame *self, if (target_read_memory (section + AARCH64_EXTRA_DATAP_OFFSET, buf, 8) != 0) { + warning (_("Failed to read the extra section address from the" + " signal frame context.")); section += size; break; } section = extract_unsigned_integer (buf, 8, byte_order); + signal_frame.extra_section = section; extra_found = true; break; } @@ -476,11 +498,48 @@ aarch64_linux_sigframe_init (const struct tramp_frame *self, if (!extra_found && section > section_end) break; } +} + +/* Implement the "init" method of struct tramp_frame. */ + +static void +aarch64_linux_sigframe_init (const struct tramp_frame *self, + frame_info_ptr this_frame, + struct trad_frame_cache *this_cache, + CORE_ADDR func) +{ + /* Read the signal context information. */ + struct aarch64_linux_sigframe signal_frame; + aarch64_linux_read_signal_frame_info (this_frame, signal_frame); + + /* Now we have all the data required to restore the registers from the + signal frame. */ + + /* Restore the general purpose registers. */ + CORE_ADDR offset = signal_frame.gpr_section; + for (int i = 0; i < 31; i++) + { + trad_frame_set_reg_addr (this_cache, AARCH64_X0_REGNUM + i, offset); + offset += AARCH64_SIGCONTEXT_REG_SIZE; + } + trad_frame_set_reg_addr (this_cache, AARCH64_SP_REGNUM, offset); + offset += AARCH64_SIGCONTEXT_REG_SIZE; + trad_frame_set_reg_addr (this_cache, AARCH64_PC_REGNUM, offset); - if (sve_regs != 0) + struct gdbarch *gdbarch = get_frame_arch (this_frame); + aarch64_gdbarch_tdep *tdep = gdbarch_tdep (gdbarch); + + /* Restore the SVE / FPSIMD registers. */ + if (tdep->has_sve () && signal_frame.sve_section != 0) { - CORE_ADDR offset; + ULONGEST vq = sve_vq_from_vl (signal_frame.vl); + CORE_ADDR sve_regs = signal_frame.sve_section; + + /* Restore VG. */ + trad_frame_set_reg_value (this_cache, AARCH64_SVE_VG_REGNUM, + sve_vg_from_vl (signal_frame.vl)); + int num_regs = gdbarch_num_regs (gdbarch); for (int i = 0; i < 32; i++) { offset = sve_regs + (i * vq * 16); @@ -510,30 +569,75 @@ aarch64_linux_sigframe_init (const struct tramp_frame *self, trad_frame_set_reg_addr (this_cache, AARCH64_SVE_FFR_REGNUM, offset); } - if (fpsimd != 0) + /* Restore the FPSIMD registers. */ + if (signal_frame.fpsimd_section != 0) { + CORE_ADDR fpsimd = signal_frame.fpsimd_section; + trad_frame_set_reg_addr (this_cache, AARCH64_FPSR_REGNUM, fpsimd + AARCH64_FPSIMD_FPSR_OFFSET); trad_frame_set_reg_addr (this_cache, AARCH64_FPCR_REGNUM, fpsimd + AARCH64_FPSIMD_FPCR_OFFSET); /* If there was no SVE section then set up the V registers. */ - if (sve_regs == 0) + if (!tdep->has_sve () || signal_frame.sve_section == 0) aarch64_linux_restore_vregs (gdbarch, this_cache, fpsimd); } - if (za_state != 0) + /* Restore the SME registers. */ + if (tdep->has_sme ()) { - /* Restore the ZA state. */ - trad_frame_set_reg_addr (this_cache, tdep->sme_za_regnum, - za_state); + if (signal_frame.za_section != 0) + { + /* Restore the ZA state. */ + trad_frame_set_reg_addr (this_cache, tdep->sme_za_regnum, + signal_frame.za_section); + } + + /* Restore/Reconstruct SVCR. */ + ULONGEST svcr = 0; + svcr |= signal_frame.za_payload ? SVCR_ZA_BIT : 0; + svcr |= signal_frame.streaming_mode ? SVCR_SM_BIT : 0; + trad_frame_set_reg_value (this_cache, tdep->sme_svcr_regnum, svcr); + + /* Restore SVG. */ + trad_frame_set_reg_value (this_cache, tdep->sme_svg_regnum, + sve_vg_from_vl (signal_frame.svl)); } - /* If SME is supported, set SVCR as well. */ - if (tdep->has_sme ()) - trad_frame_set_reg_value (this_cache, tdep->sme_svcr_regnum, svcr); + trad_frame_set_id (this_cache, frame_id_build (signal_frame.sp, func)); +} - trad_frame_set_id (this_cache, frame_id_build (sp, func)); +/* Implements the "prev_arch" method of struct tramp_frame. */ + +static struct gdbarch * +aarch64_linux_sigframe_prev_arch (frame_info_ptr this_frame, + void **frame_cache) +{ + struct trad_frame_cache *cache + = (struct trad_frame_cache *) *frame_cache; + + gdb_assert (cache != nullptr); + + struct aarch64_linux_sigframe signal_frame; + aarch64_linux_read_signal_frame_info (this_frame, signal_frame); + + /* The SVE vector length and the SME vector length may change from frame to + frame. Make sure we report the correct architecture to the previous + frame. + + We can reuse the next frame's architecture here, as it should be mostly + the same, except for potential different vg and svg values. */ + const struct target_desc *tdesc + = gdbarch_target_desc (get_frame_arch (this_frame)); + aarch64_features features = aarch64_features_from_target_desc (tdesc); + features.vq = sve_vq_from_vl (signal_frame.vl); + features.svq = (uint8_t) sve_vq_from_vl (signal_frame.svl); + + struct gdbarch_info info; + info.bfd_arch_info = bfd_lookup_arch (bfd_arch_aarch64, bfd_mach_aarch64); + info.target_desc = aarch64_read_description (features); + return gdbarch_find_by_info (info); } static const struct tramp_frame aarch64_linux_rt_sigframe = @@ -550,7 +654,9 @@ static const struct tramp_frame aarch64_linux_rt_sigframe = {0xd4000001, ULONGEST_MAX}, {TRAMP_SENTINEL_INSN, ULONGEST_MAX} }, - aarch64_linux_sigframe_init + aarch64_linux_sigframe_init, + nullptr, /* validate */ + aarch64_linux_sigframe_prev_arch, /* prev_arch */ }; /* Register maps. */ diff --git a/gdb/tramp-frame.c b/gdb/tramp-frame.c index c69ee6efc2c..94e42e9fec1 100644 --- a/gdb/tramp-frame.c +++ b/gdb/tramp-frame.c @@ -170,5 +170,6 @@ tramp_frame_prepend_unwinder (struct gdbarch *gdbarch, unwinder->stop_reason = default_frame_unwind_stop_reason; unwinder->this_id = tramp_frame_this_id; unwinder->prev_register = tramp_frame_prev_register; + unwinder->prev_arch = tramp_frame->prev_arch; frame_unwind_prepend_unwinder (gdbarch, unwinder); } diff --git a/gdb/tramp-frame.h b/gdb/tramp-frame.h index a8e4ab6dd48..5e6d1b1a7fa 100644 --- a/gdb/tramp-frame.h +++ b/gdb/tramp-frame.h @@ -21,6 +21,7 @@ #define TRAMP_FRAME_H #include "frame.h" +#include "frame-unwind.h" /* For frame_prev_arch_ftype. */ class frame_info_ptr; struct trad_frame_cache; @@ -75,6 +76,10 @@ struct tramp_frame int (*validate) (const struct tramp_frame *self, frame_info_ptr this_frame, CORE_ADDR *pc); + + /* Given the current frame in THIS_FRAME and a frame cache in FRAME_CACHE, + return the architecture of the previous frame. */ + frame_prev_arch_ftype *prev_arch; }; void tramp_frame_prepend_unwinder (struct gdbarch *gdbarch, -- 2.30.2