Commit 43d4da2c authored by Dave Martin's avatar Dave Martin Committed by Will Deacon

arm64/sve: ptrace and ELF coredump support

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: default avatarAlan Hayward <alan.hayward@arm.com>
Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Okamoto Takayuki <tokamoto@jp.fujitsu.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent fdfa976c
......@@ -38,13 +38,16 @@ struct fpsimd_state {
__uint128_t vregs[32];
u32 fpsr;
u32 fpcr;
/*
* For ptrace compatibility, pad to next 128-bit
* boundary here if extending this struct.
*/
};
};
/* the id of the last cpu to have restored this state */
unsigned int cpu;
};
#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
/* Masks for extracting the FPSR and FPCR from the FPSCR */
#define VFP_FPSCR_STAT_MASK 0xf800009f
......@@ -88,6 +91,10 @@ extern size_t sve_state_size(struct task_struct const *task);
extern void sve_alloc(struct task_struct *task);
extern void fpsimd_release_task(struct task_struct *task);
extern void fpsimd_sync_to_sve(struct task_struct *task);
extern void sve_sync_to_fpsimd(struct task_struct *task);
extern void sve_sync_from_fpsimd_zeropad(struct task_struct *task);
extern int sve_set_vector_length(struct task_struct *task,
unsigned long vl, unsigned long flags);
......@@ -104,6 +111,9 @@ extern void __init sve_setup(void);
static inline void sve_alloc(struct task_struct *task) { }
static inline void fpsimd_release_task(struct task_struct *task) { }
static inline void sve_sync_to_fpsimd(struct task_struct *task) { }
static inline void sve_sync_from_fpsimd_zeropad(struct task_struct *task) { }
static inline void sve_init_vq_map(void) { }
static inline void sve_update_vq_map(void) { }
static inline int sve_verify_vq_map(void) { return 0; }
......
......@@ -22,6 +22,7 @@
#include <linux/types.h>
#include <asm/hwcap.h>
#include <asm/sigcontext.h>
/*
......@@ -62,6 +63,8 @@
#ifndef __ASSEMBLY__
#include <linux/prctl.h>
/*
* User structures for general purpose, floating point and debug registers.
*/
......@@ -89,6 +92,141 @@ struct user_hwdebug_state {
} dbg_regs[16];
};
/* SVE/FP/SIMD state (NT_ARM_SVE) */
struct user_sve_header {
__u32 size; /* total meaningful regset content in bytes */
__u32 max_size; /* maxmium possible size for this thread */
__u16 vl; /* current vector length */
__u16 max_vl; /* maximum possible vector length */
__u16 flags;
__u16 __reserved;
};
/* Definitions for user_sve_header.flags: */
#define SVE_PT_REGS_MASK (1 << 0)
#define SVE_PT_REGS_FPSIMD 0
#define SVE_PT_REGS_SVE SVE_PT_REGS_MASK
/*
* Common SVE_PT_* flags:
* These must be kept in sync with prctl interface in <linux/ptrace.h>
*/
#define SVE_PT_VL_INHERIT (PR_SVE_VL_INHERIT >> 16)
#define SVE_PT_VL_ONEXEC (PR_SVE_SET_VL_ONEXEC >> 16)
/*
* The remainder of the SVE state follows struct user_sve_header. The
* total size of the SVE state (including header) depends on the
* metadata in the header: SVE_PT_SIZE(vq, flags) gives the total size
* of the state in bytes, including the header.
*
* Refer to <asm/sigcontext.h> for details of how to pass the correct
* "vq" argument to these macros.
*/
/* Offset from the start of struct user_sve_header to the register data */
#define SVE_PT_REGS_OFFSET \
((sizeof(struct sve_context) + (SVE_VQ_BYTES - 1)) \
/ SVE_VQ_BYTES * SVE_VQ_BYTES)
/*
* The register data content and layout depends on the value of the
* flags field.
*/
/*
* (flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD case:
*
* The payload starts at offset SVE_PT_FPSIMD_OFFSET, and is of type
* struct user_fpsimd_state. Additional data might be appended in the
* future: use SVE_PT_FPSIMD_SIZE(vq, flags) to compute the total size.
* SVE_PT_FPSIMD_SIZE(vq, flags) will never be less than
* sizeof(struct user_fpsimd_state).
*/
#define SVE_PT_FPSIMD_OFFSET SVE_PT_REGS_OFFSET
#define SVE_PT_FPSIMD_SIZE(vq, flags) (sizeof(struct user_fpsimd_state))
/*
* (flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE case:
*
* The payload starts at offset SVE_PT_SVE_OFFSET, and is of size
* SVE_PT_SVE_SIZE(vq, flags).
*
* Additional macros describe the contents and layout of the payload.
* For each, SVE_PT_SVE_x_OFFSET(args) is the start offset relative to
* the start of struct user_sve_header, and SVE_PT_SVE_x_SIZE(args) is
* the size in bytes:
*
* x type description
* - ---- -----------
* ZREGS \
* ZREG |
* PREGS | refer to <asm/sigcontext.h>
* PREG |
* FFR /
*
* FPSR uint32_t FPSR
* FPCR uint32_t FPCR
*
* Additional data might be appended in the future.
*/
#define SVE_PT_SVE_ZREG_SIZE(vq) SVE_SIG_ZREG_SIZE(vq)
#define SVE_PT_SVE_PREG_SIZE(vq) SVE_SIG_PREG_SIZE(vq)
#define SVE_PT_SVE_FFR_SIZE(vq) SVE_SIG_FFR_SIZE(vq)
#define SVE_PT_SVE_FPSR_SIZE sizeof(__u32)
#define SVE_PT_SVE_FPCR_SIZE sizeof(__u32)
#define __SVE_SIG_TO_PT(offset) \
((offset) - SVE_SIG_REGS_OFFSET + SVE_PT_REGS_OFFSET)
#define SVE_PT_SVE_OFFSET SVE_PT_REGS_OFFSET
#define SVE_PT_SVE_ZREGS_OFFSET \
__SVE_SIG_TO_PT(SVE_SIG_ZREGS_OFFSET)
#define SVE_PT_SVE_ZREG_OFFSET(vq, n) \
__SVE_SIG_TO_PT(SVE_SIG_ZREG_OFFSET(vq, n))
#define SVE_PT_SVE_ZREGS_SIZE(vq) \
(SVE_PT_SVE_ZREG_OFFSET(vq, SVE_NUM_ZREGS) - SVE_PT_SVE_ZREGS_OFFSET)
#define SVE_PT_SVE_PREGS_OFFSET(vq) \
__SVE_SIG_TO_PT(SVE_SIG_PREGS_OFFSET(vq))
#define SVE_PT_SVE_PREG_OFFSET(vq, n) \
__SVE_SIG_TO_PT(SVE_SIG_PREG_OFFSET(vq, n))
#define SVE_PT_SVE_PREGS_SIZE(vq) \
(SVE_PT_SVE_PREG_OFFSET(vq, SVE_NUM_PREGS) - \
SVE_PT_SVE_PREGS_OFFSET(vq))
#define SVE_PT_SVE_FFR_OFFSET(vq) \
__SVE_SIG_TO_PT(SVE_SIG_FFR_OFFSET(vq))
#define SVE_PT_SVE_FPSR_OFFSET(vq) \
((SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq) + \
(SVE_VQ_BYTES - 1)) \
/ SVE_VQ_BYTES * SVE_VQ_BYTES)
#define SVE_PT_SVE_FPCR_OFFSET(vq) \
(SVE_PT_SVE_FPSR_OFFSET(vq) + SVE_PT_SVE_FPSR_SIZE)
/*
* Any future extension appended after FPCR must be aligned to the next
* 128-bit boundary.
*/
#define SVE_PT_SVE_SIZE(vq, flags) \
((SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE \
- SVE_PT_SVE_OFFSET + (SVE_VQ_BYTES - 1)) \
/ SVE_VQ_BYTES * SVE_VQ_BYTES)
#define SVE_PT_SIZE(vq, flags) \
(((flags) & SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE ? \
SVE_PT_SVE_OFFSET + SVE_PT_SVE_SIZE(vq, flags) \
: SVE_PT_FPSIMD_OFFSET + SVE_PT_FPSIMD_SIZE(vq, flags))
#endif /* __ASSEMBLY__ */
#endif /* _UAPI__ASM_PTRACE_H */
......@@ -428,6 +428,66 @@ void sve_alloc(struct task_struct *task)
BUG_ON(!task->thread.sve_state);
}
/*
* Ensure that task->thread.sve_state is up to date with respect to
* the user task, irrespective of when SVE is in use or not.
*
* This should only be called by ptrace. task must be non-runnable.
* task->thread.sve_state must point to at least sve_state_size(task)
* bytes of allocated kernel memory.
*/
void fpsimd_sync_to_sve(struct task_struct *task)
{
if (!test_tsk_thread_flag(task, TIF_SVE))
fpsimd_to_sve(task);
}
/*
* Ensure that task->thread.fpsimd_state is up to date with respect to
* the user task, irrespective of whether SVE is in use or not.
*
* This should only be called by ptrace. task must be non-runnable.
* task->thread.sve_state must point to at least sve_state_size(task)
* bytes of allocated kernel memory.
*/
void sve_sync_to_fpsimd(struct task_struct *task)
{
if (test_tsk_thread_flag(task, TIF_SVE))
sve_to_fpsimd(task);
}
/*
* Ensure that task->thread.sve_state is up to date with respect to
* the task->thread.fpsimd_state.
*
* This should only be called by ptrace to merge new FPSIMD register
* values into a task for which SVE is currently active.
* task must be non-runnable.
* task->thread.sve_state must point to at least sve_state_size(task)
* bytes of allocated kernel memory.
* task->thread.fpsimd_state must already have been initialised with
* the new FPSIMD register values to be merged in.
*/
void sve_sync_from_fpsimd_zeropad(struct task_struct *task)
{
unsigned int vq;
void *sst = task->thread.sve_state;
struct fpsimd_state const *fst = &task->thread.fpsimd_state;
unsigned int i;
if (!test_tsk_thread_flag(task, TIF_SVE))
return;
vq = sve_vq_from_vl(task->thread.sve_vl);
memset(sst, 0, SVE_SIG_REGS_SIZE(vq));
for (i = 0; i < 32; ++i)
memcpy(ZREG(sst, vq, i), &fst->vregs[i],
sizeof(fst->vregs[i]));
}
int sve_set_vector_length(struct task_struct *task,
unsigned long vl, unsigned long flags)
{
......
......@@ -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,
static int __fpr_get(struct task_struct *target,
const struct user_regset *regset,
unsigned int pos, unsigned int count,
void *kbuf, void __user *ubuf)
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)
{
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 = {
......
......@@ -416,6 +416,7 @@ typedef struct elf64_shdr {
#define NT_ARM_HW_BREAK 0x402 /* ARM hardware breakpoint registers */
#define NT_ARM_HW_WATCH 0x403 /* ARM hardware watchpoint registers */
#define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
#define NT_ARM_SVE 0x405 /* ARM Scalable Vector Extension registers */
#define NT_METAG_CBUF 0x500 /* Metag catch buffer registers */
#define NT_METAG_RPIPE 0x501 /* Metag read pipeline state */
#define NT_METAG_TLS 0x502 /* Metag TLS pointer */
......
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