| Message ID | 1416977391-24231-2-git-send-email-takahiro.akashi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Akashi, On Wed, Nov 26, 2014 at 04:49:46AM +0000, AKASHI Takahiro wrote: > This regeset is intended to be used to get and set a system call number > while tracing. > There was some discussion about possible approaches to do so: > > (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, > and update regs->syscallno later on in syscall_trace_enter(), or > (2) define a dedicated regset for this purpose as on s390, or > (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm > > Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to > tracer as well as that secure_computing() expects a changed syscall number, > especially case of -1, to be visible before this function returns in > syscall_trace_enter(), (1) doesn't work well. > We will take (2) since it looks much cleaner. > > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > --- > arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 2 files changed, 36 insertions(+) > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 8a4ae8e..8b98781 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset, > return ret; > } > > +static int system_call_get(struct task_struct *target, > + const struct user_regset *regset, > + unsigned int pos, unsigned int count, > + void *kbuf, void __user *ubuf) > +{ > + struct pt_regs *regs = task_pt_regs(target); > + > + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, > + ®s->syscallno, 0, -1); Does this work for big-endian machines? regs->syscallno is a u64, but the regset defines it as an int. I think you need to copy to a temporary register first. Will
On 11/26/2014 09:41 PM, Will Deacon wrote: > Hi Akashi, > > On Wed, Nov 26, 2014 at 04:49:46AM +0000, AKASHI Takahiro wrote: >> This regeset is intended to be used to get and set a system call number >> while tracing. >> There was some discussion about possible approaches to do so: >> >> (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, >> and update regs->syscallno later on in syscall_trace_enter(), or >> (2) define a dedicated regset for this purpose as on s390, or >> (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm >> >> Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to >> tracer as well as that secure_computing() expects a changed syscall number, >> especially case of -1, to be visible before this function returns in >> syscall_trace_enter(), (1) doesn't work well. >> We will take (2) since it looks much cleaner. >> >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >> --- >> arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ >> include/uapi/linux/elf.h | 1 + >> 2 files changed, 36 insertions(+) >> >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c >> index 8a4ae8e..8b98781 100644 >> --- a/arch/arm64/kernel/ptrace.c >> +++ b/arch/arm64/kernel/ptrace.c >> @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset, >> return ret; >> } >> >> +static int system_call_get(struct task_struct *target, >> + const struct user_regset *regset, >> + unsigned int pos, unsigned int count, >> + void *kbuf, void __user *ubuf) >> +{ >> + struct pt_regs *regs = task_pt_regs(target); >> + >> + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, >> + ®s->syscallno, 0, -1); > > Does this work for big-endian machines? regs->syscallno is a u64, but the > regset defines it as an int. I think you need to copy to a temporary > register first. Right. I will fix it. Do you prefer to use s32, instead of int, like other regsets? Thanks, -Takahiro AKASHI > Will >
On Thu, Nov 27, 2014 at 05:53:36AM +0000, AKASHI Takahiro wrote: > On 11/26/2014 09:41 PM, Will Deacon wrote: > > On Wed, Nov 26, 2014 at 04:49:46AM +0000, AKASHI Takahiro wrote: > >> This regeset is intended to be used to get and set a system call number > >> while tracing. > >> There was some discussion about possible approaches to do so: > >> > >> (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, > >> and update regs->syscallno later on in syscall_trace_enter(), or > >> (2) define a dedicated regset for this purpose as on s390, or > >> (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm > >> > >> Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to > >> tracer as well as that secure_computing() expects a changed syscall number, > >> especially case of -1, to be visible before this function returns in > >> syscall_trace_enter(), (1) doesn't work well. > >> We will take (2) since it looks much cleaner. > >> > >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > >> --- > >> arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ > >> include/uapi/linux/elf.h | 1 + > >> 2 files changed, 36 insertions(+) > >> > >> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > >> index 8a4ae8e..8b98781 100644 > >> --- a/arch/arm64/kernel/ptrace.c > >> +++ b/arch/arm64/kernel/ptrace.c > >> @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset, > >> return ret; > >> } > >> > >> +static int system_call_get(struct task_struct *target, > >> + const struct user_regset *regset, > >> + unsigned int pos, unsigned int count, > >> + void *kbuf, void __user *ubuf) > >> +{ > >> + struct pt_regs *regs = task_pt_regs(target); > >> + > >> + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, > >> + ®s->syscallno, 0, -1); > > > > Does this work for big-endian machines? regs->syscallno is a u64, but the > > regset defines it as an int. I think you need to copy to a temporary > > register first. > > Right. I will fix it. > Do you prefer to use s32, instead of int, like other regsets? I don't have a preference either way. It would be great to have a new revision of these patches ASAP if you're targetting 3.19. Will
On 11/27/2014 11:10 PM, Will Deacon wrote: > On Thu, Nov 27, 2014 at 05:53:36AM +0000, AKASHI Takahiro wrote: >> On 11/26/2014 09:41 PM, Will Deacon wrote: >>> On Wed, Nov 26, 2014 at 04:49:46AM +0000, AKASHI Takahiro wrote: >>>> This regeset is intended to be used to get and set a system call number >>>> while tracing. >>>> There was some discussion about possible approaches to do so: >>>> >>>> (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, >>>> and update regs->syscallno later on in syscall_trace_enter(), or >>>> (2) define a dedicated regset for this purpose as on s390, or >>>> (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm >>>> >>>> Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to >>>> tracer as well as that secure_computing() expects a changed syscall number, >>>> especially case of -1, to be visible before this function returns in >>>> syscall_trace_enter(), (1) doesn't work well. >>>> We will take (2) since it looks much cleaner. >>>> >>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >>>> --- >>>> arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ >>>> include/uapi/linux/elf.h | 1 + >>>> 2 files changed, 36 insertions(+) >>>> >>>> diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c >>>> index 8a4ae8e..8b98781 100644 >>>> --- a/arch/arm64/kernel/ptrace.c >>>> +++ b/arch/arm64/kernel/ptrace.c >>>> @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset, >>>> return ret; >>>> } >>>> >>>> +static int system_call_get(struct task_struct *target, >>>> + const struct user_regset *regset, >>>> + unsigned int pos, unsigned int count, >>>> + void *kbuf, void __user *ubuf) >>>> +{ >>>> + struct pt_regs *regs = task_pt_regs(target); >>>> + >>>> + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, >>>> + ®s->syscallno, 0, -1); >>> >>> Does this work for big-endian machines? regs->syscallno is a u64, but the >>> regset defines it as an int. I think you need to copy to a temporary >>> register first. >> >> Right. I will fix it. >> Do you prefer to use s32, instead of int, like other regsets? > > I don't have a preference either way. > > It would be great to have a new revision of these patches ASAP if you're > targetting 3.19. Yeah, definitely. -Takahiro AKASHI > Will > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 8a4ae8e..8b98781 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -551,6 +551,32 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset, return ret; } +static int system_call_get(struct task_struct *target, + const struct user_regset *regset, + unsigned int pos, unsigned int count, + void *kbuf, void __user *ubuf) +{ + struct pt_regs *regs = task_pt_regs(target); + + return user_regset_copyout(&pos, &count, &kbuf, &ubuf, + ®s->syscallno, 0, -1); +} + +static int system_call_set(struct task_struct *target, + const struct user_regset *regset, + unsigned int pos, unsigned int count, + const void *kbuf, const void __user *ubuf) +{ + int syscallno, ret; + + ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &syscallno, 0, -1); + if (ret) + return ret; + + task_pt_regs(target)->syscallno = syscallno; + return ret; +} + enum aarch64_regset { REGSET_GPR, REGSET_FPR, @@ -559,6 +585,7 @@ enum aarch64_regset { REGSET_HW_BREAK, REGSET_HW_WATCH, #endif + REGSET_SYSTEM_CALL, }; static const struct user_regset aarch64_regsets[] = { @@ -608,6 +635,14 @@ static const struct user_regset aarch64_regsets[] = { .set = hw_break_set, }, #endif + [REGSET_SYSTEM_CALL] = { + .core_note_type = NT_ARM_SYSTEM_CALL, + .n = 1, + .size = sizeof(int), + .align = sizeof(int), + .get = system_call_get, + .set = system_call_set, + }, }; static const struct user_regset_view user_aarch64_view = { diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index ea9bf25..71e1d0e 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -397,6 +397,7 @@ typedef struct elf64_shdr { #define NT_ARM_TLS 0x401 /* ARM TLS register */ #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_METAG_CBUF 0x500 /* Metag catch buffer registers */ #define NT_METAG_RPIPE 0x501 /* Metag read pipeline state */ #define NT_METAG_TLS 0x502 /* Metag TLS pointer */
This regeset is intended to be used to get and set a system call number while tracing. There was some discussion about possible approaches to do so: (1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly, and update regs->syscallno later on in syscall_trace_enter(), or (2) define a dedicated regset for this purpose as on s390, or (3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to tracer as well as that secure_computing() expects a changed syscall number, especially case of -1, to be visible before this function returns in syscall_trace_enter(), (1) doesn't work well. We will take (2) since it looks much cleaner. Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> --- arch/arm64/kernel/ptrace.c | 35 +++++++++++++++++++++++++++++++++++ include/uapi/linux/elf.h | 1 + 2 files changed, 36 insertions(+)