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arm64/sve: ptrace and ELF coredump support

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This patch defines and implements a new regset NT_ARM_SVE, which
describes a thread's SVE register state.  This allows a debugger to
manipulate the SVE state, as well as being included in ELF
coredumps for post-mortem debugging.

Because the regset size and layout are dependent on the thread's
current vector length, it is not possible to define a C struct to
describe the regset contents as is done for existing regsets.
Instead, and for the same reasons, NT_ARM_SVE is based on the
freeform variable-layout approach used for the SVE signal frame.

Additionally, to reduce debug overhead when debugging threads that
might or might not have live SVE register state, NT_ARM_SVE may be
presented in one of two different formats: the old struct
user_fpsimd_state format is embedded for describing the state of a
thread with no live SVE state, whereas a new variable-layout
structure is embedded for describing live SVE state.  This avoids a
debugger needing to poll NT_PRFPREG in addition to NT_ARM_SVE, and
allows existing userspace code to handle the non-SVE case without
too much modification.

For this to work, NT_ARM_SVE is defined with a fixed-format header
of type struct user_sve_header, which the recipient can use to
figure out the content, size and layout of the reset of the regset.
Accessor macros are defined to allow the vector-length-dependent
parts of the regset to be manipulated.

Signed-off-by: Alan Hayward <alan.hayward@arm.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Okamoto Takayuki <tokamoto@jp.fujitsu.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Dave Martin
2017-10-31 15:51:13 +00:00
committed by Will Deacon
parent fdfa976cae
commit 43d4da2c45
5 changed files with 482 additions and 9 deletions
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280
arch/arm64/kernel/ptrace.c
View File

@@ -32,6 +32,7 @@
#include <linux/security.h>
#include <linux/init.h>
#include <linux/signal.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/perf_event.h>
#include <linux/hw_breakpoint.h>
@@ -40,6 +41,7 @@
#include <linux/elf.h>
#include <asm/compat.h>
#include <asm/cpufeature.h>
#include <asm/debug-monitors.h>
#include <asm/pgtable.h>
#include <asm/stacktrace.h>
@@ -618,17 +620,56 @@ static int gpr_set(struct task_struct *target, const struct user_regset *regset,
/*
* TODO: update fp accessors for lazy context switching (sync/flush hwstate)
*/
static int __fpr_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf, unsigned int start_pos)
{
struct user_fpsimd_state *uregs;
sve_sync_to_fpsimd(target);
uregs = &target->thread.fpsimd_state.user_fpsimd;
return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs,
start_pos, start_pos + sizeof(*uregs));
}
static int fpr_get(struct task_struct *target, const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
struct user_fpsimd_state *uregs;
uregs = &target->thread.fpsimd_state.user_fpsimd;
if (target == current)
fpsimd_preserve_current_state();
return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
return __fpr_get(target, regset, pos, count, kbuf, ubuf, 0);
}
static int __fpr_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf,
unsigned int start_pos)
{
int ret;
struct user_fpsimd_state newstate;
/*
* Ensure target->thread.fpsimd_state is up to date, so that a
* short copyin can't resurrect stale data.
*/
sve_sync_to_fpsimd(target);
newstate = target->thread.fpsimd_state.user_fpsimd;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate,
start_pos, start_pos + sizeof(newstate));
if (ret)
return ret;
target->thread.fpsimd_state.user_fpsimd = newstate;
return ret;
}
static int fpr_set(struct task_struct *target, const struct user_regset *regset,
@@ -636,15 +677,14 @@ static int fpr_set(struct task_struct *target, const struct user_regset *regset,
const void *kbuf, const void __user *ubuf)
{
int ret;
struct user_fpsimd_state newstate =
target->thread.fpsimd_state.user_fpsimd;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate, 0, -1);
ret = __fpr_set(target, regset, pos, count, kbuf, ubuf, 0);
if (ret)
return ret;
target->thread.fpsimd_state.user_fpsimd = newstate;
sve_sync_from_fpsimd_zeropad(target);
fpsimd_flush_task_state(target);
return ret;
}
@@ -702,6 +742,215 @@ static int system_call_set(struct task_struct *target,
return ret;
}
#ifdef CONFIG_ARM64_SVE
static void sve_init_header_from_task(struct user_sve_header *header,
struct task_struct *target)
{
unsigned int vq;
memset(header, 0, sizeof(*header));
header->flags = test_tsk_thread_flag(target, TIF_SVE) ?
SVE_PT_REGS_SVE : SVE_PT_REGS_FPSIMD;
if (test_tsk_thread_flag(target, TIF_SVE_VL_INHERIT))
header->flags |= SVE_PT_VL_INHERIT;
header->vl = target->thread.sve_vl;
vq = sve_vq_from_vl(header->vl);
header->max_vl = sve_max_vl;
if (WARN_ON(!sve_vl_valid(sve_max_vl)))
header->max_vl = header->vl;
header->size = SVE_PT_SIZE(vq, header->flags);
header->max_size = SVE_PT_SIZE(sve_vq_from_vl(header->max_vl),
SVE_PT_REGS_SVE);
}
static unsigned int sve_size_from_header(struct user_sve_header const *header)
{
return ALIGN(header->size, SVE_VQ_BYTES);
}
static unsigned int sve_get_size(struct task_struct *target,
const struct user_regset *regset)
{
struct user_sve_header header;
if (!system_supports_sve())
return 0;
sve_init_header_from_task(&header, target);
return sve_size_from_header(&header);
}
static int sve_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
{
int ret;
struct user_sve_header header;
unsigned int vq;
unsigned long start, end;
if (!system_supports_sve())
return -EINVAL;
/* Header */
sve_init_header_from_task(&header, target);
vq = sve_vq_from_vl(header.vl);
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &header,
0, sizeof(header));
if (ret)
return ret;
if (target == current)
fpsimd_preserve_current_state();
/* Registers: FPSIMD-only case */
BUILD_BUG_ON(SVE_PT_FPSIMD_OFFSET != sizeof(header));
if ((header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD)
return __fpr_get(target, regset, pos, count, kbuf, ubuf,
SVE_PT_FPSIMD_OFFSET);
/* Otherwise: full SVE case */
BUILD_BUG_ON(SVE_PT_SVE_OFFSET != sizeof(header));
start = SVE_PT_SVE_OFFSET;
end = SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq);
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
target->thread.sve_state,
start, end);
if (ret)
return ret;
start = end;
end = SVE_PT_SVE_FPSR_OFFSET(vq);
ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
start, end);
if (ret)
return ret;
/*
* Copy fpsr, and fpcr which must follow contiguously in
* struct fpsimd_state:
*/
start = end;
end = SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE;
ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
&target->thread.fpsimd_state.fpsr,
start, end);
if (ret)
return ret;
start = end;
end = sve_size_from_header(&header);
return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
start, end);
}
static int sve_set(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
const void *kbuf, const void __user *ubuf)
{
int ret;
struct user_sve_header header;
unsigned int vq;
unsigned long start, end;
if (!system_supports_sve())
return -EINVAL;
/* Header */
if (count < sizeof(header))
return -EINVAL;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &header,
0, sizeof(header));
if (ret)
goto out;
/*
* Apart from PT_SVE_REGS_MASK, all PT_SVE_* flags are consumed by
* sve_set_vector_length(), which will also validate them for us:
*/
ret = sve_set_vector_length(target, header.vl,
((unsigned long)header.flags & ~SVE_PT_REGS_MASK) << 16);
if (ret)
goto out;
/* Actual VL set may be less than the user asked for: */
vq = sve_vq_from_vl(target->thread.sve_vl);
/* Registers: FPSIMD-only case */
BUILD_BUG_ON(SVE_PT_FPSIMD_OFFSET != sizeof(header));
if ((header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD) {
ret = __fpr_set(target, regset, pos, count, kbuf, ubuf,
SVE_PT_FPSIMD_OFFSET);
clear_tsk_thread_flag(target, TIF_SVE);
goto out;
}
/* Otherwise: full SVE case */
/*
* If setting a different VL from the requested VL and there is
* register data, the data layout will be wrong: don't even
* try to set the registers in this case.
*/
if (count && vq != sve_vq_from_vl(header.vl)) {
ret = -EIO;
goto out;
}
sve_alloc(target);
/*
* Ensure target->thread.sve_state is up to date with target's
* FPSIMD regs, so that a short copyin leaves trailing registers
* unmodified.
*/
fpsimd_sync_to_sve(target);
set_tsk_thread_flag(target, TIF_SVE);
BUILD_BUG_ON(SVE_PT_SVE_OFFSET != sizeof(header));
start = SVE_PT_SVE_OFFSET;
end = SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq);
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
target->thread.sve_state,
start, end);
if (ret)
goto out;
start = end;
end = SVE_PT_SVE_FPSR_OFFSET(vq);
ret = user_regset_copyin_ignore(&pos, &count, &kbuf, &ubuf,
start, end);
if (ret)
goto out;
/*
* Copy fpsr, and fpcr which must follow contiguously in
* struct fpsimd_state:
*/
start = end;
end = SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE;
ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
&target->thread.fpsimd_state.fpsr,
start, end);
out:
fpsimd_flush_task_state(target);
return ret;
}
#endif /* CONFIG_ARM64_SVE */
enum aarch64_regset {
REGSET_GPR,
REGSET_FPR,
@@ -711,6 +960,9 @@ enum aarch64_regset {
REGSET_HW_WATCH,
#endif
REGSET_SYSTEM_CALL,
#ifdef CONFIG_ARM64_SVE
REGSET_SVE,
#endif
};
static const struct user_regset aarch64_regsets[] = {
@@ -768,6 +1020,18 @@ static const struct user_regset aarch64_regsets[] = {
.get = system_call_get,
.set = system_call_set,
},
#ifdef CONFIG_ARM64_SVE
[REGSET_SVE] = { /* Scalable Vector Extension */
.core_note_type = NT_ARM_SVE,
.n = DIV_ROUND_UP(SVE_PT_SIZE(SVE_VQ_MAX, SVE_PT_REGS_SVE),
SVE_VQ_BYTES),
.size = SVE_VQ_BYTES,
.align = SVE_VQ_BYTES,
.get = sve_get,
.set = sve_set,
.get_size = sve_get_size,
},
#endif
};
static const struct user_regset_view user_aarch64_view = {