| Message ID | 20210119220637.494476-3-avagin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64/ptrace: allow to get all registers on syscall traps | expand |
On Tue, Jan 19, 2021 at 02:06:36PM -0800, Andrei Vagin wrote: > This is an alternative to NT_PRSTATUS that clobbers ip/r12 on AArch32, > x7 on AArch64 when a tracee is stopped in syscall entry or syscall exit > traps. > > Signed-off-by: Andrei Vagin <avagin@gmail.com> This approach looks like it works, though I still think adding an option for this under PTRACE_SETOPTIONS would be less intrusive. Adding a shadow regset like this also looks like it would cause the gp regs to be pointlessly be dumped twice in a core dump. Avoiding that might require hacks in the core code... > --- > arch/arm64/kernel/ptrace.c | 39 ++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/elf.h | 1 + > 2 files changed, 40 insertions(+) > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 1863f080cb07..b8e4c2ddf636 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -591,6 +591,15 @@ static int gpr_get(struct task_struct *target, > return ret; > } > > +static int gpr_get_full(struct task_struct *target, > + const struct user_regset *regset, > + struct membuf to) > +{ > + struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs; > + > + return membuf_write(&to, uregs, sizeof(*uregs)); > +} > + > static int gpr_set(struct task_struct *target, const struct user_regset *regset, > unsigned int pos, unsigned int count, > const void *kbuf, const void __user *ubuf) > @@ -1088,6 +1097,7 @@ static int tagged_addr_ctrl_set(struct task_struct *target, const struct > > enum aarch64_regset { > REGSET_GPR, > + REGSET_GPR_FULL, If we go with this approach, "REGSET_GPR_RAW" might be a preferable name. Both regs represent all the regs ("full"), but REGSET_GPR is mangled by the kernel. > REGSET_FPR, > REGSET_TLS, > #ifdef CONFIG_HAVE_HW_BREAKPOINT > @@ -1119,6 +1129,14 @@ static const struct user_regset aarch64_regsets[] = { > .regset_get = gpr_get, > .set = gpr_set > }, > + [REGSET_GPR_FULL] = { > + .core_note_type = NT_ARM_PRSTATUS, Similarly, something like NT_ARM_PRSTATUS_RAW or similar. > + .n = sizeof(struct user_pt_regs) / sizeof(u64), > + .size = sizeof(u64), > + .align = sizeof(u64), > + .regset_get = gpr_get_full, > + .set = gpr_set > + }, > [REGSET_FPR] = { > .core_note_type = NT_PRFPREG, > .n = sizeof(struct user_fpsimd_state) / sizeof(u32), > @@ -1225,6 +1243,7 @@ static const struct user_regset_view user_aarch64_view = { > #ifdef CONFIG_COMPAT > enum compat_regset { > REGSET_COMPAT_GPR, > + REGSET_COMPAT_GPR_FULL, > REGSET_COMPAT_VFP, > }; > > @@ -1285,6 +1304,18 @@ static int compat_gpr_get(struct task_struct *target, > return 0; > } > > +/* compat_gpr_get_full doesn't overwrite x12 like compat_gpr_get. */ > +static int compat_gpr_get_full(struct task_struct *target, > + const struct user_regset *regset, > + struct membuf to) > +{ > + int i = 0; > + > + while (to.left) > + membuf_store(&to, compat_get_user_reg(target, i++)); > + return 0; > +} > + > static int compat_gpr_set(struct task_struct *target, > const struct user_regset *regset, > unsigned int pos, unsigned int count, > @@ -1435,6 +1466,14 @@ static const struct user_regset aarch32_regsets[] = { > .regset_get = compat_gpr_get, > .set = compat_gpr_set > }, > + [REGSET_COMPAT_GPR_FULL] = { > + .core_note_type = NT_ARM_PRSTATUS, > + .n = COMPAT_ELF_NGREG, > + .size = sizeof(compat_elf_greg_t), > + .align = sizeof(compat_elf_greg_t), > + .regset_get = compat_gpr_get_full, > + .set = compat_gpr_set > + }, > [REGSET_COMPAT_VFP] = { > .core_note_type = NT_ARM_VFP, > .n = VFP_STATE_SIZE / sizeof(compat_ulong_t), > diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h > index 30f68b42eeb5..a2086d19263a 100644 > --- a/include/uapi/linux/elf.h > +++ b/include/uapi/linux/elf.h > @@ -426,6 +426,7 @@ typedef struct elf64_shdr { > #define NT_ARM_PACA_KEYS 0x407 /* ARM pointer authentication address keys */ > #define NT_ARM_PACG_KEYS 0x408 /* ARM pointer authentication generic key */ > #define NT_ARM_TAGGED_ADDR_CTRL 0x409 /* arm64 tagged address control (prctl()) */ What happened to 0x40a..0x40f? [...] Cheers ---Dave
On Wed, Jan 27, 2021 at 02:53:07PM +0000, Dave Martin wrote: > On Tue, Jan 19, 2021 at 02:06:36PM -0800, Andrei Vagin wrote: > > This is an alternative to NT_PRSTATUS that clobbers ip/r12 on AArch32, > > x7 on AArch64 when a tracee is stopped in syscall entry or syscall exit > > traps. > > > > Signed-off-by: Andrei Vagin <avagin@gmail.com> > > This approach looks like it works, though I still think adding an option > for this under PTRACE_SETOPTIONS would be less intrusive. Dave, thank you for the feedback. I will prepare a patch with an option and then we will see what looks better. > > Adding a shadow regset like this also looks like it would cause the gp > regs to be pointlessly be dumped twice in a core dump. Avoiding that > might require hacks in the core code... > > > > --- > > arch/arm64/kernel/ptrace.c | 39 ++++++++++++++++++++++++++++++++++++++ > > include/uapi/linux/elf.h | 1 + > > 2 files changed, 40 insertions(+) > > > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > > index 1863f080cb07..b8e4c2ddf636 100644 > > --- a/arch/arm64/kernel/ptrace.c > > +++ b/arch/arm64/kernel/ptrace.c > > @@ -591,6 +591,15 @@ static int gpr_get(struct task_struct *target, > > return ret; > > } > > > > +static int gpr_get_full(struct task_struct *target, > > + const struct user_regset *regset, > > + struct membuf to) > > +{ > > + struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs; > > + > > + return membuf_write(&to, uregs, sizeof(*uregs)); > > +} > > + > > static int gpr_set(struct task_struct *target, const struct user_regset *regset, > > unsigned int pos, unsigned int count, > > const void *kbuf, const void __user *ubuf) > > @@ -1088,6 +1097,7 @@ static int tagged_addr_ctrl_set(struct task_struct *target, const struct > > > > enum aarch64_regset { > > REGSET_GPR, > > + REGSET_GPR_FULL, > > If we go with this approach, "REGSET_GPR_RAW" might be a preferable > name. Both regs represent all the regs ("full"), but REGSET_GPR is > mangled by the kernel. I agree that REGSET_GPR_RAW looks better in this case. > > > REGSET_FPR, > > REGSET_TLS, > > #ifdef CONFIG_HAVE_HW_BREAKPOINT > > @@ -1119,6 +1129,14 @@ static const struct user_regset aarch64_regsets[] = { > > .regset_get = gpr_get, > > .set = gpr_set > > }, > > + [REGSET_GPR_FULL] = { > > + .core_note_type = NT_ARM_PRSTATUS, ... > > diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h > > index 30f68b42eeb5..a2086d19263a 100644 > > --- a/include/uapi/linux/elf.h > > +++ b/include/uapi/linux/elf.h > > @@ -426,6 +426,7 @@ typedef struct elf64_shdr { > > #define NT_ARM_PACA_KEYS 0x407 /* ARM pointer authentication address keys */ > > #define NT_ARM_PACG_KEYS 0x408 /* ARM pointer authentication generic key */ > > #define NT_ARM_TAGGED_ADDR_CTRL 0x409 /* arm64 tagged address control (prctl()) */ > > What happened to 0x40a..0x40f? shame on me :) > > [...] > > Cheers > ---Dave
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 1863f080cb07..b8e4c2ddf636 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -591,6 +591,15 @@ static int gpr_get(struct task_struct *target, return ret; } +static int gpr_get_full(struct task_struct *target, + const struct user_regset *regset, + struct membuf to) +{ + struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs; + + return membuf_write(&to, uregs, sizeof(*uregs)); +} + static int gpr_set(struct task_struct *target, const struct user_regset *regset, unsigned int pos, unsigned int count, const void *kbuf, const void __user *ubuf) @@ -1088,6 +1097,7 @@ static int tagged_addr_ctrl_set(struct task_struct *target, const struct enum aarch64_regset { REGSET_GPR, + REGSET_GPR_FULL, REGSET_FPR, REGSET_TLS, #ifdef CONFIG_HAVE_HW_BREAKPOINT @@ -1119,6 +1129,14 @@ static const struct user_regset aarch64_regsets[] = { .regset_get = gpr_get, .set = gpr_set }, + [REGSET_GPR_FULL] = { + .core_note_type = NT_ARM_PRSTATUS, + .n = sizeof(struct user_pt_regs) / sizeof(u64), + .size = sizeof(u64), + .align = sizeof(u64), + .regset_get = gpr_get_full, + .set = gpr_set + }, [REGSET_FPR] = { .core_note_type = NT_PRFPREG, .n = sizeof(struct user_fpsimd_state) / sizeof(u32), @@ -1225,6 +1243,7 @@ static const struct user_regset_view user_aarch64_view = { #ifdef CONFIG_COMPAT enum compat_regset { REGSET_COMPAT_GPR, + REGSET_COMPAT_GPR_FULL, REGSET_COMPAT_VFP, }; @@ -1285,6 +1304,18 @@ static int compat_gpr_get(struct task_struct *target, return 0; } +/* compat_gpr_get_full doesn't overwrite x12 like compat_gpr_get. */ +static int compat_gpr_get_full(struct task_struct *target, + const struct user_regset *regset, + struct membuf to) +{ + int i = 0; + + while (to.left) + membuf_store(&to, compat_get_user_reg(target, i++)); + return 0; +} + static int compat_gpr_set(struct task_struct *target, const struct user_regset *regset, unsigned int pos, unsigned int count, @@ -1435,6 +1466,14 @@ static const struct user_regset aarch32_regsets[] = { .regset_get = compat_gpr_get, .set = compat_gpr_set }, + [REGSET_COMPAT_GPR_FULL] = { + .core_note_type = NT_ARM_PRSTATUS, + .n = COMPAT_ELF_NGREG, + .size = sizeof(compat_elf_greg_t), + .align = sizeof(compat_elf_greg_t), + .regset_get = compat_gpr_get_full, + .set = compat_gpr_set + }, [REGSET_COMPAT_VFP] = { .core_note_type = NT_ARM_VFP, .n = VFP_STATE_SIZE / sizeof(compat_ulong_t), diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index 30f68b42eeb5..a2086d19263a 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -426,6 +426,7 @@ typedef struct elf64_shdr { #define NT_ARM_PACA_KEYS 0x407 /* ARM pointer authentication address keys */ #define NT_ARM_PACG_KEYS 0x408 /* ARM pointer authentication generic key */ #define NT_ARM_TAGGED_ADDR_CTRL 0x409 /* arm64 tagged address control (prctl()) */ +#define NT_ARM_PRSTATUS 0x410 /* ARM general-purpose registers */ #define NT_ARC_V2 0x600 /* ARCv2 accumulator/extra registers */ #define NT_VMCOREDD 0x700 /* Vmcore Device Dump Note */ #define NT_MIPS_DSP 0x800 /* MIPS DSP ASE registers */
This is an alternative to NT_PRSTATUS that clobbers ip/r12 on AArch32, x7 on AArch64 when a tracee is stopped in syscall entry or syscall exit traps. Signed-off-by: Andrei Vagin <avagin@gmail.com> --- arch/arm64/kernel/ptrace.c | 39 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/elf.h | 1 + 2 files changed, 40 insertions(+)