Subject: [PATCH v13 01/10] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature

From: [email-masked] (David Long)
Date: Thu, 23 Jun 2016 09:48:11 -0400

On 06/19/2016 10:43 PM, Li Bin wrote:
>
>
> on 2016/6/3 11:26, David Long wrote:
>> From: "David A. Long" <[email-masked]>
>>
>> Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64, including supporting
>> functions and defines.
>>
>> Signed-off-by: David A. Long <[email-masked]>
>> ---
>>   arch/arm64/Kconfig              |   1 +
>>   arch/arm64/include/asm/ptrace.h |  54 +++++++++++++++++-
>>   arch/arm64/kernel/ptrace.c      | 118 ++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 172 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 76747d9..0f7a624 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -85,6 +85,7 @@ config ARM64
>>   	select HAVE_PERF_EVENTS
>>   	select HAVE_PERF_REGS
>>   	select HAVE_PERF_USER_STACK_DUMP
>> +	select HAVE_REGS_AND_STACK_ACCESS_API
>>   	select HAVE_RCU_TABLE_FREE
>>   	select HAVE_SYSCALL_TRACEPOINTS
>>   	select IOMMU_DMA if IOMMU_SUPPORT
>> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
>> index a307eb6..c130f2b 100644
>> --- a/arch/arm64/include/asm/ptrace.h
>> +++ b/arch/arm64/include/asm/ptrace.h
>> @@ -74,6 +74,7 @@
>>   #define COMPAT_PT_DATA_ADDR		0x10004
>>   #define COMPAT_PT_TEXT_END_ADDR		0x10008
>>   #ifndef __ASSEMBLY__
>> +#include <linux/bug.h>
>>
>>   /* sizeof(struct user) for AArch32 */
>>   #define COMPAT_USER_SZ	296
>> @@ -119,6 +120,8 @@ struct pt_regs {
>>   	u64 syscallno;
>>   };
>>
>> +#define MAX_REG_OFFSET offsetof(struct pt_regs, pstate)
>> +
>>   #define arch_has_single_step()	(1)
>>
>>   #ifdef CONFIG_COMPAT
>> @@ -147,6 +150,55 @@ struct pt_regs {
>>   #define user_stack_pointer(regs) \
>>   	(!compat_user_mode(regs) ? (regs)->sp : (regs)->compat_sp)
>>
>> +extern int regs_query_register_offset(const char *name);
>> +extern const char *regs_query_register_name(unsigned int offset);
>> +extern bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr);
>> +extern unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
>> +					       unsigned int n);
>> +
>> +/**
>> + * regs_get_register() - get register value from its offset
>> + * @regs:	   pt_regs from which register value is gotten
>> + * @offset:    offset of the register.
>> + *
>> + * regs_get_register returns the value of a register whose offset from @regs.
>> + * The @offset is the offset of the register in struct pt_regs.
>> + * If @offset is bigger than MAX_REG_OFFSET, this returns 0.
>> + */
>> +static inline u64 regs_get_register(struct pt_regs *regs,
>> +					      unsigned int offset)
>> +{
>> +	u64 val = 0;
>> +
>> +	WARN_ON(offset & 7);
>> +
>> +	offset >>= 3;
>
> Here, the offset is 3-bits right shifted. So,
>
>> +	switch (offset) {
>> +	case	0 ... 30:
>> +		val = regs->regs[offset];
>> +		break;
>> +	case offsetof(struct pt_regs, sp):
>
> here should be shifted too, as
>
> 	case offsetof(struct pt_regs, sp) >> 3:
>
>
>> +		val = regs->sp;
>> +		break;
>> +	case offsetof(struct pt_regs, pc):
>
> and here,
>
>> +		val = regs->pc;
>> +		break;
>> +	case offsetof(struct pt_regs, pstate):
>
> and here.
>
> thanks,
> Li Bin
>

Thanks for pointing this out.  It has been fixed now for the v14 patch.

>> +		val = regs->pstate;
>> +		break;
>> +	default:
>> +		val = 0;
>> +	}
>> +
>> +	return val;
>> +}
>> +
>> +/* Valid only for Kernel mode traps. */
>> +static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
>> +{
>> +	return regs->sp;
>> +}
>> +
>>   static inline unsigned long regs_return_value(struct pt_regs *regs)
>>   {
>>   	return regs->regs[0];
>> @@ -156,7 +208,7 @@ static inline unsigned long regs_return_value(struct pt_regs *regs)
>>   struct task_struct;
>>   int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task);
>>
>> -#define instruction_pointer(regs)	((unsigned long)(regs)->pc)
>> +#define instruction_pointer(regs)	((regs)->pc)
>>
>>   extern unsigned long profile_pc(struct pt_regs *regs);
>>
>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
>> index 3f6cd5c..2c88c33 100644
>> --- a/arch/arm64/kernel/ptrace.c
>> +++ b/arch/arm64/kernel/ptrace.c
>> @@ -48,6 +48,124 @@
>>   #define CREATE_TRACE_POINTS
>>   #include <trace/events/syscalls.h>
>>
>> +struct pt_regs_offset {
>> +	const char *name;
>> +	int offset;
>> +};
>> +
>> +#define REG_OFFSET_NAME(r) {.name = #r, .offset = offsetof(struct pt_regs, r)}
>> +#define REG_OFFSET_END {.name = NULL, .offset = 0}
>> +#define	GPR_OFFSET_NAME(r)	\
>> +	{.name = "x" #r, .offset = offsetof(struct pt_regs, regs[r])}
>> +
>> +static const struct pt_regs_offset regoffset_table[] = {
>> +	GPR_OFFSET_NAME(0),
>> +	GPR_OFFSET_NAME(1),
>> +	GPR_OFFSET_NAME(2),
>> +	GPR_OFFSET_NAME(3),
>> +	GPR_OFFSET_NAME(4),
>> +	GPR_OFFSET_NAME(5),
>> +	GPR_OFFSET_NAME(6),
>> +	GPR_OFFSET_NAME(7),
>> +	GPR_OFFSET_NAME(8),
>> +	GPR_OFFSET_NAME(9),
>> +	GPR_OFFSET_NAME(10),
>> +	GPR_OFFSET_NAME(11),
>> +	GPR_OFFSET_NAME(12),
>> +	GPR_OFFSET_NAME(13),
>> +	GPR_OFFSET_NAME(14),
>> +	GPR_OFFSET_NAME(15),
>> +	GPR_OFFSET_NAME(16),
>> +	GPR_OFFSET_NAME(17),
>> +	GPR_OFFSET_NAME(18),
>> +	GPR_OFFSET_NAME(19),
>> +	GPR_OFFSET_NAME(20),
>> +	GPR_OFFSET_NAME(21),
>> +	GPR_OFFSET_NAME(22),
>> +	GPR_OFFSET_NAME(23),
>> +	GPR_OFFSET_NAME(24),
>> +	GPR_OFFSET_NAME(25),
>> +	GPR_OFFSET_NAME(26),
>> +	GPR_OFFSET_NAME(27),
>> +	GPR_OFFSET_NAME(28),
>> +	GPR_OFFSET_NAME(29),
>> +	GPR_OFFSET_NAME(30),
>> +	{.name = "lr", .offset = offsetof(struct pt_regs, regs[30])},
>> +	REG_OFFSET_NAME(sp),
>> +	REG_OFFSET_NAME(pc),
>> +	REG_OFFSET_NAME(pstate),
>> +	REG_OFFSET_END,
>> +};
>> +
>> +/**
>> + * regs_query_register_offset() - query register offset from its name
>> + * @name:	the name of a register
>> + *
>> + * regs_query_register_offset() returns the offset of a register in struct
>> + * pt_regs from its name. If the name is invalid, this returns -EINVAL;
>> + */
>> +int regs_query_register_offset(const char *name)
>> +{
>> +	const struct pt_regs_offset *roff;
>> +
>> +	for (roff = regoffset_table; roff->name != NULL; roff++)
>> +		if (!strcmp(roff->name, name))
>> +			return roff->offset;
>> +	return -EINVAL;
>> +}
>> +
>> +/**
>> + * regs_query_register_name() - query register name from its offset
>> + * @offset:	the offset of a register in struct pt_regs.
>> + *
>> + * regs_query_register_name() returns the name of a register from its
>> + * offset in struct pt_regs. If the @offset is invalid, this returns NULL;
>> + */
>> +const char *regs_query_register_name(unsigned int offset)
>> +{
>> +	const struct pt_regs_offset *roff;
>> +
>> +	for (roff = regoffset_table; roff->name != NULL; roff++)
>> +		if (roff->offset == offset)
>> +			return roff->name;
>> +	return NULL;
>> +}
>> +
>> +/**
>> + * regs_within_kernel_stack() - check the address in the stack
>> + * @regs:      pt_regs which contains kernel stack pointer.
>> + * @addr:      address which is checked.
>> + *
>> + * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
>> + * If @addr is within the kernel stack, it returns true. If not, returns false.
>> + */
>> +bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
>> +{
>> +	return ((addr & ~(THREAD_SIZE - 1))  ==
>> +		(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) ||
>> +		on_irq_stack(addr, raw_smp_processor_id());
>> +}
>> +
>> +/**
>> + * regs_get_kernel_stack_nth() - get Nth entry of the stack
>> + * @regs:	pt_regs which contains kernel stack pointer.
>> + * @n:		stack entry number.
>> + *
>> + * regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
>> + * is specified by @regs. If the @n th entry is NOT in the kernel stack,
>> + * this returns 0.
>> + */
>> +unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs, unsigned int n)
>> +{
>> +	unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
>> +
>> +	addr += n;
>> +	if (regs_within_kernel_stack(regs, (unsigned long)addr))
>> +		return *addr;
>> +	else
>> +		return 0;
>> +}
>> +
>>   /*
>>    * TODO: does not yet catch signals sent when the child dies.
>>    * in exit.c or in signal.c.
>>
>

Thanks,
-dl