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powerpc/ptrace: Add support for PTRACE_SYSEMU
This is a patch that adds support for PTRACE_SYSEMU ptrace request in PowerPC architecture. When ptrace(PTRACE_SYSEMU, ...) request is called, it will be handled by the arch independent function ptrace_resume(), which will tag the task with the TIF_SYSCALL_EMU flag. This flag needs to be handled from a platform dependent point of view, which is what this patch does. This patch adds this task's flag as part of the _TIF_SYSCALL_DOTRACE, which is the MACRO that is used to trace syscalls at entrance/exit. Since TIF_SYSCALL_EMU is now part of _TIF_SYSCALL_DOTRACE, if the task has _TIF_SYSCALL_DOTRACE set, it will hit do_syscall_trace_enter() at syscall entrance and do_syscall_trace_leave() at syscall leave. do_syscall_trace_enter() needs to handle the TIF_SYSCALL_EMU flag properly, which will interrupt the syscall executing if TIF_SYSCALL_EMU is set. The output values should not be changed, i.e. the return value (r3) should contain the original syscall argument on exit. With this flag set, the syscall is not executed fundamentally, because do_syscall_trace_enter() is returning -1 which is bigger than NR_syscall, thus, skipping the syscall execution and exiting userspace. Signed-off-by: Breno Leitao <leitao@debian.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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16d7c69c89
commit
5521eb4bca
3 changed files with 18 additions and 1 deletions
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@ -81,6 +81,7 @@ extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_FSCHECK 3 /* Check FS is USER_DS on return */
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#define TIF_FSCHECK 3 /* Check FS is USER_DS on return */
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#define TIF_SYSCALL_EMU 4 /* syscall emulation active */
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#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
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#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
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#define TIF_PATCH_PENDING 6 /* pending live patching update */
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#define TIF_PATCH_PENDING 6 /* pending live patching update */
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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@ -120,9 +121,10 @@ extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src
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#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
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#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
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#define _TIF_NOHZ (1<<TIF_NOHZ)
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#define _TIF_NOHZ (1<<TIF_NOHZ)
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#define _TIF_FSCHECK (1<<TIF_FSCHECK)
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#define _TIF_FSCHECK (1<<TIF_FSCHECK)
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#define _TIF_SYSCALL_EMU (1<<TIF_SYSCALL_EMU)
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#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
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_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
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_TIF_NOHZ)
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_TIF_NOHZ | _TIF_SYSCALL_EMU)
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#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
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#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
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_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
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_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
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@ -160,6 +160,10 @@ struct pt_regs {
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#define PTRACE_GETVSRREGS 0x1b
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#define PTRACE_GETVSRREGS 0x1b
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#define PTRACE_SETVSRREGS 0x1c
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#define PTRACE_SETVSRREGS 0x1c
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/* Syscall emulation defines */
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#define PTRACE_SYSEMU 0x1d
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#define PTRACE_SYSEMU_SINGLESTEP 0x1e
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/*
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/*
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* Get or set a debug register. The first 16 are DABR registers and the
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* Get or set a debug register. The first 16 are DABR registers and the
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* second 16 are IABR registers.
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* second 16 are IABR registers.
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@ -2508,6 +2508,7 @@ void ptrace_disable(struct task_struct *child)
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{
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{
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/* make sure the single step bit is not set. */
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/* make sure the single step bit is not set. */
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user_disable_single_step(child);
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user_disable_single_step(child);
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clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
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}
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}
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#ifdef CONFIG_PPC_ADV_DEBUG_REGS
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#ifdef CONFIG_PPC_ADV_DEBUG_REGS
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@ -3264,6 +3265,16 @@ long do_syscall_trace_enter(struct pt_regs *regs)
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{
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{
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user_exit();
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user_exit();
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if (test_thread_flag(TIF_SYSCALL_EMU)) {
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ptrace_report_syscall(regs);
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/*
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* Returning -1 will skip the syscall execution. We want to
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* avoid clobbering any register also, thus, not 'gotoing'
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* skip label.
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*/
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return -1;
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}
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/*
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/*
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* The tracer may decide to abort the syscall, if so tracehook
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* The tracer may decide to abort the syscall, if so tracehook
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* will return !0. Note that the tracer may also just change
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* will return !0. Note that the tracer may also just change
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