Subject: Re: [PATCH V4 6/8] powerpc, ptrace: Enable support for transactional memory register sets

From: Anshuman Khandual <[email-masked]>
Date: Fri, 21 Nov 2014 18:41:46 +0530

On 11/19/2014 02:48 AM, Sukadev Bhattiprolu wrote:
> Anshuman Khandual [[email-masked]] wrote:
> | This patch enables get and set of transactional memory related register
> | sets through PTRACE_GETREGSET-PTRACE_SETREGSET interface by implementing
> | four new powerpc specific register sets i.e REGSET_TM_SPR, REGSET_TM_CGPR,
> | REGSET_TM_CFPR, REGSET_CVMX support corresponding to these following new
> | ELF core note types added previously in this regard.
> | 
> | 	(1) NT_PPC_TM_SPR
> | 	(2) NT_PPC_TM_CGPR
> | 	(3) NT_PPC_TM_CFPR
> | 	(4) NT_PPC_TM_CVMX
> | 
> | Signed-off-by: Anshuman Khandual <[email-masked]>
> | ---
> |  arch/powerpc/include/uapi/asm/elf.h |   2 +
> |  arch/powerpc/kernel/ptrace.c        | 666 +++++++++++++++++++++++++++++++++++-
> |  2 files changed, 653 insertions(+), 15 deletions(-)
> | 
> | diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
> | index 59dad11..fdc8e2f 100644
> | --- a/arch/powerpc/include/uapi/asm/elf.h
> | +++ b/arch/powerpc/include/uapi/asm/elf.h
> | @@ -91,6 +91,8 @@
> | 
> |  #define ELF_NGREG	48	/* includes nip, msr, lr, etc. */
> |  #define ELF_NFPREG	33	/* includes fpscr */
> | +#define ELF_NVMX	34	/* includes all vector registers */
> | +#define ELF_NTMSPRREG	7	/* includes TM sprs, org_msr, dscr, tar, ppr */
> | 
> |  typedef unsigned long elf_greg_t64;
> |  typedef elf_greg_t64 elf_gregset_t64[ELF_NGREG];
> | diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
> | index 2bbbd10..b279947 100644
> | --- a/arch/powerpc/kernel/ptrace.c
> | +++ b/arch/powerpc/kernel/ptrace.c
> | @@ -63,6 +63,11 @@ struct pt_regs_offset {
> |  	{.name = STR(gpr##num), .offset = offsetof(struct pt_regs, gpr[num])}
> |  #define REG_OFFSET_END {.name = NULL, .offset = 0}
> | 
> | +/* Some common structure offsets */
> | +#define TSO(f)	(offsetof(struct thread_struct, f))
> | +#define TVSO(f)	(offsetof(struct thread_vr_state, f))
> | +#define TFSO(f)	(offsetof(struct thread_fp_state, f))
> | +
> |  static const struct pt_regs_offset regoffset_table[] = {
> |  	GPR_OFFSET_NAME(0),
> |  	GPR_OFFSET_NAME(1),
> | @@ -792,6 +797,534 @@ static int evr_set(struct task_struct *target, const struct user_regset *regset,
> |  }
> |  #endif /* CONFIG_SPE */
> | 
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +/*
> | + * tm_spr_active
> | + *
> | + * This function checks number of available regisers in
> | + * the transactional memory SPR category.
> | + */
> | +static int tm_spr_active(struct task_struct *target,
> | +			 const struct user_regset *regset)
> | +{
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return 0;
> | +
> | +	return regset->n;
> | +}
> | +
> | +/*
> | + * tm_spr_get
> | + *
> | + * This function gets transactional memory related SPR registers
> | + *
> | + * Userspace interface buffer layout:
> | + *
> | + * struct {
> | + *	u64		tm_tfhar;
> | + *	u64		tm_texasr;
> | + *	u64		tm_tfiar;
> | + *	unsigned long	tm_orig_msr;
> | + *	unsigned long	tm_tar;
> | + *	unsigned long	tm_ppr;
> | + *	unsigned long	tm_dscr;
> | + * };
> | + */
> | +static int tm_spr_get(struct task_struct *target,
> | +		      const struct user_regset *regset,
> | +		      unsigned int pos, unsigned int count,
> | +		      void *kbuf, void __user *ubuf)
> | +{
> | +	int ret;
> | +
> | +	/* Build tests */
> | +	BUILD_BUG_ON(TSO(tm_tfhar) + sizeof(u64) != TSO(tm_texasr));
> | +	BUILD_BUG_ON(TSO(tm_texasr) + sizeof(u64) != TSO(tm_tfiar));
> | +	BUILD_BUG_ON(TSO(tm_tfiar) + sizeof(u64) != TSO(tm_orig_msr));
> | +	BUILD_BUG_ON(TSO(tm_orig_msr) +	sizeof(unsigned long) +
> Can we replace TSO(tm_orig_msr) + sizeof(unsigned long) with
> TSO(ckpt_regs) ?

Yeah we can.

> | +				sizeof(struct pt_regs) != TSO(tm_tar));
> | +	BUILD_BUG_ON(TSO(tm_tar) + sizeof(unsigned long) != TSO(tm_ppr));
> | +	BUILD_BUG_ON(TSO(tm_ppr) + sizeof(unsigned long) != TSO(tm_dscr));
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	/* Flush the states */
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	/* TFHAR register */
> | +	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tfhar, 0, sizeof(u64));
> 
> The last two parameters, (start_pos, end_pos) are easy to understand
> here, but...

Okay.

> 
> | +
> | +	/* TEXASR register */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_texasr, sizeof(u64),
> | +				2 * sizeof(u64));
> 
> ... gets harder to understand here and subsequent fields below.
> 
> Given that you already do the BUILD_BUG_ON() tests above, how about
> using TSO(tm_texasr) and TSO(tfiar) here for start_pos and end_pos ?

Hmm, I understand that as it looks kind of ugly, but writing to/from
the user level buffer is done looking at the user interface buffer
structure layout mentioned below.

 * struct {
 *      u64             tm_tfhar;
 *      u64             tm_texasr;
 *      u64             tm_tfiar;
 *      unsigned long   tm_orig_msr;
 *      unsigned long   tm_tar;
 *      unsigned long   tm_ppr;
 *      unsigned long   tm_dscr;
 * };

Looking at this structure will help some one understand the copy in/out
process and it's order better.
 
> 
> Also, how about just returning if the copyout fails ?  If the first
> copyout fails, we will still check 'if(!ret)' several times below.

Hmm, thats true. But the code flow is very similar to that of gpr_get/
gpr_set functions though it has a BUILD_BUG_ON check in between. The
rational is to stop copyout/in when we hit the first error and not to 
proceed any further. We can return from the first error itself.

> 
> | +
> | +	/* TFIAR register */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tfiar,
> | +				2 * sizeof(u64), 3 * sizeof(u64));
> | +
> | +	/* TM checkpointed original MSR */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_orig_msr, 3 * sizeof(u64),
> | +				3 * sizeof(u64) + sizeof(unsigned long));
> | +
> | +	/* TM checkpointed TAR register */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tar, 3 * sizeof(u64) +
> | +				sizeof(unsigned long) ,
> | +				3 * sizeof(u64) + 2 * sizeof(unsigned long));
> | +
> | +	/* TM checkpointed PPR register */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_ppr, 3 * sizeof(u64) +
> | +				2 * sizeof(unsigned long),
> | +				3 * sizeof(u64) + 3 * sizeof(unsigned long));
> | +
> | +	/* TM checkpointed DSCR register */
> | +	if (!ret)
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_dscr, 3 * sizeof(u64) +
> | +				3 * sizeof(unsigned long),
> | +				3 * sizeof(u64) + 4 * sizeof(unsigned long));
> | +	return ret;
> | +}
> | +
> | +/*
> | + * tm_spr_set
> | + *
> | + * This function sets transactional memory related SPR registers
> | + *
> | + * Userspace interface buffer layout:
> | + *
> | + * struct {
> | + *	u64		tm_tfhar;
> | + *	u64		tm_texasr;
> | + *	u64		tm_tfiar;
> | + *	unsigned long	tm_orig_msr;
> | + *	unsigned long	tm_tar;
> | + *	unsigned long	tm_ppr;
> | + *	unsigned long	tm_dscr;
> | + * };
> | + */
> | +static int tm_spr_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;
> | +
> | +	/* Build tests */
> | +	BUILD_BUG_ON(TSO(tm_tfhar) + sizeof(u64) != TSO(tm_texasr));
> | +	BUILD_BUG_ON(TSO(tm_texasr) + sizeof(u64) != TSO(tm_tfiar));
> | +	BUILD_BUG_ON(TSO(tm_orig_msr) + sizeof(unsigned long)
> 
> Can we replace TSO(tm_orig_msr) + sizeof(unsigned long) with
> TSO(ckpt_regs) ?

Yeah we can.

> 
> | +				+ sizeof(struct pt_regs) != TSO(tm_tar));
> | +	BUILD_BUG_ON(TSO(tm_tar) + sizeof(unsigned long) != TSO(tm_ppr));
> | +	BUILD_BUG_ON(TSO(tm_ppr) + sizeof(unsigned long) != TSO(tm_dscr));
> | +	BUILD_BUG_ON(TSO(tm_tfiar) + sizeof(u64) != TSO(tm_orig_msr));
> 
> How about moving this last line up after the check for TSO(tm_tfiar) ?

Done.

> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	/* Flush the states */
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	/* TFHAR register */
> | +	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tfhar, 0, sizeof(u64));
> | +
> | +	/* TEXASR register */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_texasr, sizeof(u64),
> | +				2 * sizeof(u64));
> 
> Return if copyin() fails ?

Yeah both the cases are similar.

> 
> | +
> | +	/* TFIAR register */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tfiar,
> | +				 2 * sizeof(u64), 3 * sizeof(u64));
> | +
> | +
> | +	/* TM checkpointed orig MSR */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_orig_msr, 3 * sizeof(u64),
> | +				3 * sizeof(u64) + sizeof(unsigned long));
> | +
> | +
> | +	/* TM checkpointed TAR register */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_tar, 3 * sizeof(u64) +
> | +				sizeof(unsigned long), 3 * sizeof(u64) +
> | +				2 * sizeof(unsigned long));
> | +
> | +	/* TM checkpointed PPR register */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_ppr, 3 * sizeof(u64) +
> | +				2 * sizeof(unsigned long), 3 * sizeof(u64) +
> | +				3 * sizeof(unsigned long));
> | +
> | +	/* TM checkpointed DSCR register */
> | +	if (!ret)
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +				&target->thread.tm_dscr, 3 * sizeof(u64) +
> | +				3 * sizeof(unsigned long), 3 * sizeof(u64) +
> | +				4 * sizeof(unsigned long));
> | +	return ret;
> | +}
> | +
> | +/*
> | + * tm_cgpr_active
> | + *
> | + * This function checks the number of available regisers in
> | + * transaction checkpointed GPR category.
> | + */
> | +static int tm_cgpr_active(struct task_struct *target,
> | +			  const struct user_regset *regset)
> | +{
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return 0;
> | +
> | +	return regset->n;
> | +}
> | +
> | +/*
> | + * tm_cgpr_get
> | + *
> | + * This function gets transaction checkpointed GPR registers
> | + *
> | + * When the transaction is active, 'ckpt_regs' holds all the checkpointed
> | + * GPR register values for the current transaction to fall back on if it
> | + * aborts in between. This function gets those checkpointed GPR registers.
> | + *
> | + * Userspace interface buffer layout:
> | + *
> | + * struct data {
> | + *	struct pt_regs ckpt_regs;
> | + * };
> | + */
> | +static int tm_cgpr_get(struct task_struct *target,
> | +			const struct user_regset *regset,
> | +			unsigned int pos, unsigned int count,
> | +			void *kbuf, void __user *ubuf)
> | +{
> | +	int ret;
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +					&target->thread.ckpt_regs, 0,
> | +					sizeof(struct pt_regs));
> | +	return ret;
> | +}
> | +
> | +/*
> | + * tm_cgpr_set
> | + *
> | + * This function sets in transaction checkpointed GPR registers
> | + *
> | + * When the transaction is active, 'ckpt_regs' holds the checkpointed
> | + * GPR register values for the current transaction to fall back on if it
> | + * aborts in between. This function sets those checkpointed GPR registers.
> | + *
> | + * Userspace intaerface buffer:
> | + *
> | + * struct data {
> | + *	struct pt_regs ckpt_regs;
> | + * };
> | + */
> | +static int tm_cgpr_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;
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +					&target->thread.ckpt_regs, 0,
> | +					sizeof(struct pt_regs));
> | +	return ret;
> | +}
> | +
> | +/*
> | + * tm_cfpr_active
> | + *
> | + * This function checks number of available regisers in
> | + * transaction checkpointed FPR category.
> | + */
> | +static int tm_cfpr_active(struct task_struct *target,
> | +				const struct user_regset *regset)
> | +{
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return 0;
> | +
> | +	return regset->n;
> | +}
> | +
> | +/*
> | + * tm_cfpr_get
> | + *
> | + * This function gets in transaction checkpointed FPR registers
> | + *
> | + * When the transaction is active 'fp_state' holds the checkpointed
> | + * values for the current transaction to fall back on if it aborts
> | + * in between. This function gets those checkpointed FPR registers.
> | + *
> | + * Userspace interface buffer layout:
> | + *
> | + * struct data {
> | + *	u64	fpr[32];
> | + *	u64	fpscr;
> | + *};
> | + */
> | +static int tm_cfpr_get(struct task_struct *target,
> | +			const struct user_regset *regset,
> | +			unsigned int pos, unsigned int count,
> | +			void *kbuf, void __user *ubuf)
> | +{
> | +	u64 buf[33];
> | +	int i;
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	/* copy to local buffer then write that out */
> | +	for (i = 0; i < 32 ; i++)
> | +		buf[i] = target->thread.TS_FPR(i);
> | +	buf[32] = target->thread.fp_state.fpscr;
> | +	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
> | +}
> | +
> | +/*
> | + * tm_cfpr_set
> | + *
> | + * This function sets in transaction checkpointed FPR registers
> | + *
> | + * When the transaction is active 'fp_state' holds the checkpointed
> | + * FPR register values for the current transaction to fall back on
> | + * if it aborts in between. This function sets these checkpointed
> | + * FPR registers.
> | + *
> | + * Userspace interface buffer layout:
> | + *
> | + * struct data {
> | + *	u64	fpr[32];
> | + *	u64	fpscr;
> | + *};
> | + */
> | +static int tm_cfpr_set(struct task_struct *target,
> | +			const struct user_regset *regset,
> | +			unsigned int pos, unsigned int count,
> | +			const void *kbuf, const void __user *ubuf)
> | +{
> | +	u64 buf[33];
> | +	int i;
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	/* copy to local buffer then write that out */
> | +	i = user_regset_copyin(&pos, &count, &kbuf, &ubuf, buf, 0, -1);
> | +	if (i)
> | +		return i;
> | +	for (i = 0; i < 32 ; i++)
> | +		target->thread.TS_FPR(i) = buf[i];
> | +	target->thread.fp_state.fpscr = buf[32];
> | +	return 0;
> | +}
> | +
> | +/*
> | + * tm_cvmx_active
> | + *
> | + * This function checks the number of available regisers in
> | + * checkpointed VMX category.
> | + */
> | +static int tm_cvmx_active(struct task_struct *target,
> | +				const struct user_regset *regset)
> | +{
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return 0;
> | +
> | +	return regset->n;
> | +}
> | +
> | +/*
> | + * tm_cvmx_get
> | + *
> | + * This function gets in transaction checkpointed VMX registers
> | + *
> | + * When the transaction is active 'vr_state' and 'vr_save' hold
> | + * the checkpointed values for the current transaction to fall
> | + * back on if it aborts in between.
> | + *
> | + * User interface buffer:
> | + *
> | + * struct data {
> | + *	vector128	vr[32];
> | + *	vector128	vscr;
> | + *	vector128	vrsave;
> | + *};
> | + */
> | +static int tm_cvmx_get(struct task_struct *target,
> | +			const struct user_regset *regset,
> | +			unsigned int pos, unsigned int count,
> | +			void *kbuf, void __user *ubuf)
> | +{
> | +	int ret;
> | +
> | +	BUILD_BUG_ON(TVSO(vscr) != TVSO(vr[32]));
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	/* Flush the state */
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
> | +					&target->thread.vr_state, 0,
> | +					33 * sizeof(vector128));
> | +	if (!ret) {
> | +		/*
> | +		 * Copy out only the low-order word of vrsave.
> | +		 */
> | +		union {
> | +			elf_vrreg_t reg;
> | +			u32 word;
> | +		} vrsave;
> | +		memset(&vrsave, 0, sizeof(vrsave));
> | +		vrsave.word = target->thread.vrsave;
> | +		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &vrsave,
> | +						33 * sizeof(vector128), -1);
> | +	}
> | +
> | +	return ret;
> | +}
> | +
> | +/*
> | + * tm_cvmx_set
> | + *
> | + * This function sets in transaction checkpointed VMX registers
> | + *
> | + * When the transaction is active 'vr_state' and 'vr_save' hold
> | + * the checkpointed values for the current transaction to fall
> | + * back on if it aborts in between.
> | + *
> | + * Userspace interface buffer:
> | + *
> | + * struct data {
> | + *	vector128	vr[32];
> | + *	vector128	vscr;
> | + *	vector128	vrsave;
> | + *};
> | + */
> | +static int tm_cvmx_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;
> | +
> | +	BUILD_BUG_ON(TVSO(vscr) != TVSO(vr[32]));
> | +
> | +	if (!cpu_has_feature(CPU_FTR_TM))
> | +		return -ENODEV;
> | +
> | +	if (!MSR_TM_ACTIVE(target->thread.regs->msr))
> | +		return -ENODATA;
> | +
> | +	flush_fp_to_thread(target);
> | +	flush_altivec_to_thread(target);
> | +	flush_tmregs_to_thread(target);
> | +
> | +	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
> | +					&target->thread.vr_state, 0,
> | +					33 * sizeof(vector128));
> | +	if (!ret && count > 0) {
> | +		/*
> | +		 * We use only the first word of vrsave.
> 
> For consistency with the _get() function above, s/first/low-order/ ?

Done.

> | +		 */
> | +		union {
> | +			elf_vrreg_t reg;
> | +			u32 word;
> | +		} vrsave;
> | +		memset(&vrsave, 0, sizeof(vrsave));
> | +		vrsave.word = target->thread.vrsave;
> | +		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &vrsave,
> | +						33 * sizeof(vector128), -1);
> | +		if (!ret)
> | +			target->thread.vrsave = vrsave.word;
> | +	}
> | +
> | +	return ret;
> | +}
> | +#endif	/* CONFIG_PPC_TRANSACTIONAL_MEM */
> | 
> |  /*
> |   * These are our native regset flavors.
> | @@ -808,6 +1341,12 @@ enum powerpc_regset {
> |  #ifdef CONFIG_SPE
> |  	REGSET_SPE,
> |  #endif
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +	REGSET_TM_SPR,		/* TM specific SPR registers */
> | +	REGSET_TM_CGPR,		/* TM checkpointed GPR registers */
> | +	REGSET_TM_CFPR,		/* TM checkpointed FPR registers */
> | +	REGSET_TM_CVMX,		/* TM checkpointed VMX registers */
> | +#endif
> |  };
> | 
> |  static const struct user_regset native_regsets[] = {
> | @@ -842,6 +1381,28 @@ static const struct user_regset native_regsets[] = {
> |  		.active = evr_active, .get = evr_get, .set = evr_set
> |  	},
> |  #endif
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +	[REGSET_TM_SPR] = {
> | +		.core_note_type = NT_PPC_TM_SPR, .n = ELF_NTMSPRREG,
> | +		.size = sizeof(u64), .align = sizeof(u64),
> | +		.active = tm_spr_active, .get = tm_spr_get, .set = tm_spr_set
> | +	},
> | +	[REGSET_TM_CGPR] = {
> | +		.core_note_type = NT_PPC_TM_CGPR, .n = ELF_NGREG,
> | +		.size = sizeof(long), .align = sizeof(long),
> | +		.active = tm_cgpr_active, .get = tm_cgpr_get, .set = tm_cgpr_set
> | +	},
> | +	[REGSET_TM_CFPR] = {
> | +		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
> | +		.size = sizeof(double), .align = sizeof(double),
> | +		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
> | +	},
> | +	[REGSET_TM_CVMX] = {
> | +		.core_note_type = NT_PPC_TM_CVMX, .n = ELF_NVMX,
> | +		.size = sizeof(vector128), .align = sizeof(vector128),
> | +		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
> | +	},
> | +#endif
> |  };
> | 
> |  static const struct user_regset_view user_ppc_native_view = {
> | @@ -852,24 +1413,35 @@ static const struct user_regset_view user_ppc_native_view = {
> |  #ifdef CONFIG_PPC64
> |  #include <linux/compat.h>
> | 
> | -static int gpr32_get(struct task_struct *target,
> | +static int common_gpr32_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, bool in_tm)
> |  {
> | -	const unsigned long *regs = &target->thread.regs->gpr[0];
> | +	const unsigned long *regs;
> |  	compat_ulong_t *k = kbuf;
> |  	compat_ulong_t __user *u = ubuf;
> |  	compat_ulong_t reg;
> |  	int i;
> | 
> | -	if (target->thread.regs == NULL)
> | -		return -EIO;
> | +	if (in_tm) {
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +		regs = &target->thread.ckpt_regs.gpr[0];
> | +#endif
> 
> regs uninitialized if in_tm is true and CONFIG_PPC_TRANSACTIONAL_MEM
> is false ? It appears that it cannot/should not happen, how about BUGON() ?
> or at least regs = NULL to silence compiler warnings ?

Yeah it cannot happen, seems like compiler is able to figure that out as
I dont get any warning because of that. BUG_ON sounds like a good option
after the if-else block to verify whether the regs variable got any valid
address value to it or not. Also we can start with regs = NULL at the
starting of the function as well.

> 
> 
> | +	} else {
> | +		regs = &target->thread.regs->gpr[0];
> | 
> | -	if (!FULL_REGS(target->thread.regs)) {
> | -		/* We have a partial register set.  Fill 14-31 with bogus values */
> | -		for (i = 14; i < 32; i++)
> | -			target->thread.regs->gpr[i] = NV_REG_POISON; 
> | +		if (target->thread.regs == NULL)
> | +			return -EIO;
> | +
> | +		if (!FULL_REGS(target->thread.regs)) {
> | +			/*
> | +			 * We have a partial register set.
> | +			 * Fill 14-31 with bogus values.
> | +			 */
> | +			for (i = 14; i < 32; i++)
> | +				target->thread.regs->gpr[i] = NV_REG_POISON;
> | +		}
> |  	}
> | 
> |  	pos /= sizeof(reg);
> | @@ -909,20 +1481,28 @@ static int gpr32_get(struct task_struct *target,
> |  					PT_REGS_COUNT * sizeof(reg), -1);
> |  }
> | 
> | -static int gpr32_set(struct task_struct *target,
> | +static int common_gpr32_set(struct task_struct *target,
> |  		     const struct user_regset *regset,
> |  		     unsigned int pos, unsigned int count,
> | -		     const void *kbuf, const void __user *ubuf)
> | +		     const void *kbuf, const void __user *ubuf, bool in_tm)
> |  {
> | -	unsigned long *regs = &target->thread.regs->gpr[0];
> | +	unsigned long *regs;
> |  	const compat_ulong_t *k = kbuf;
> |  	const compat_ulong_t __user *u = ubuf;
> |  	compat_ulong_t reg;
> | 
> | -	if (target->thread.regs == NULL)
> | -		return -EIO;
> | +	if (in_tm) {
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +		regs = &target->thread.ckpt_regs.gpr[0];
> | +#endif
> 
> ditto

Done.

> 
> | +	} else {
> | +		regs = &target->thread.regs->gpr[0];
> | 
> | -	CHECK_FULL_REGS(target->thread.regs);
> | +		if (target->thread.regs == NULL)
> | +			return -EIO;
> | +
> | +		CHECK_FULL_REGS(target->thread.regs);
> | +	}
> | 
> |  	pos /= sizeof(reg);
> |  	count /= sizeof(reg);
> | @@ -982,6 +1562,39 @@ static int gpr32_set(struct task_struct *target,
> |  					 (PT_TRAP + 1) * sizeof(reg), -1);
> |  }
> | 
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +static int tm_cgpr32_get(struct task_struct *target,
> | +		     const struct user_regset *regset,
> | +		     unsigned int pos, unsigned int count,
> | +		     void *kbuf, void __user *ubuf)
> | +{
> | +	return common_gpr32_get(target, regset, pos, count, kbuf, ubuf, 1);
> | +}
> | +
> | +static int tm_cgpr32_set(struct task_struct *target,
> | +		     const struct user_regset *regset,
> | +		     unsigned int pos, unsigned int count,
> | +		     const void *kbuf, const void __user *ubuf)
> | +{
> | +	return common_gpr32_set(target, regset, pos, count, kbuf, ubuf, 0);
> | +}
> | +#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
> | +
> | +static int gpr32_get(struct task_struct *target,
> | +		     const struct user_regset *regset,
> | +		     unsigned int pos, unsigned int count,
> | +		     void *kbuf, void __user *ubuf)
> | +{
> | +	return common_gpr32_get(target, regset, pos, count, kbuf, ubuf, 0);
> | +}
> | +
> | +static int gpr32_set(struct task_struct *target,
> | +		     const struct user_regset *regset,
> | +		     unsigned int pos, unsigned int count,
> | +		     const void *kbuf, const void __user *ubuf)
> | +{
> | +	return common_gpr32_set(target, regset, pos, count, kbuf, ubuf, 0);
> | +}
> |  /*
> |   * These are the regset flavors matching the CONFIG_PPC32 native set.
> |   */
> | @@ -1010,6 +1623,29 @@ static const struct user_regset compat_regsets[] = {
> |  		.active = evr_active, .get = evr_get, .set = evr_set
> |  	},
> |  #endif
> | +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> | +	[REGSET_TM_SPR] = {
> | +		.core_note_type = NT_PPC_TM_SPR, .n = ELF_NTMSPRREG,
> | +		.size = sizeof(u64), .align = sizeof(u64),
> | +		.active = tm_spr_active, .get = tm_spr_get, .set = tm_spr_set
> | +	},
> | +	[REGSET_TM_CGPR] = {
> | +		.core_note_type = NT_PPC_TM_CGPR, .n = ELF_NGREG,
> | +		.size = sizeof(long), .align = sizeof(long),
> | +		.active = tm_cgpr_active,
> | +		.get = tm_cgpr32_get, .set = tm_cgpr32_set
> | +	},
> | +	[REGSET_TM_CFPR] = {
> | +		.core_note_type = NT_PPC_TM_CFPR, .n = ELF_NFPREG,
> | +		.size = sizeof(double), .align = sizeof(double),
> | +		.active = tm_cfpr_active, .get = tm_cfpr_get, .set = tm_cfpr_set
> | +	},
> | +	[REGSET_TM_CVMX] = {
> | +		.core_note_type = NT_PPC_TM_CVMX, .n = ELF_NVMX,
> | +		.size = sizeof(vector128), .align = sizeof(vector128),
> | +		.active = tm_cvmx_active, .get = tm_cvmx_get, .set = tm_cvmx_set
> | +	},
> | +#endif
> |  };
> | 
> |  static const struct user_regset_view user_ppc_compat_view = {
> | -- 
> | 1.9.3
>