Re: [PATCH 2/3] arm64/ptrace: introduce NT_ARM_PRSTATUS to get a full set of registers
From: Dave Martin <Dave.Martin@arm.com>
Date: 2021-01-27 14:56:48
Also in:
lkml
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 <redacted>
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...
quoted hunk ↗ jump to hunk
--- 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.
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
+ .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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel