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sme: Fixup sigframe gdbarch when vg/svg changes

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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 <simon.marchi@efficios.com>
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
This commit is contained in:
Luis Machado 2023-02-02 14:00:58 +00:00
parent f62b3d21ec
commit 5add3fce49
3 changed files with 198 additions and 86 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

278
gdb/aarch64-linux-tdep.c
View File

@ -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<aarch64_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);
enum bfd_endian byte_order
= gdbarch_byte_order (get_frame_arch (this_frame));
/* Read in the integer registers. */
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;
}
}
if (sve_regs != 0)
/* 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++)
{
CORE_ADDR offset;
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);
struct gdbarch *gdbarch = get_frame_arch (this_frame);
aarch64_gdbarch_tdep *tdep = gdbarch_tdep<aarch64_gdbarch_tdep> (gdbarch);
/* Restore the SVE / FPSIMD registers. */
if (tdep->has_sve () && signal_frame.sve_section != 0)
{
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. */

1
gdb/tramp-frame.c
View File

@ -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);
}

5
gdb/tramp-frame.h
View File

@ -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,