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ptrace: Migrate to use SYSCALL_TRACE flag 

On architectures using the generic syscall entry code the architecture
independent syscall work is moved to flags in thread_info::syscall_work.
This removes architecture dependencies and frees up TIF bits.

Define SYSCALL_WORK_SYSCALL_TRACE, use it in the generic entry code and
convert the code which uses the TIF specific helper functions to use the
new *_syscall_work() helpers which either resolve to the new mode for users
of the generic entry code or to the TIF based functions for the other
architectures.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20201116174206.2639648-7-krisman@collabora.com
This commit is contained in:
Gabriel Krisman Bertazi 2020-11-16 12:42:02 -05:00 committed by Thomas Gleixner
parent 524666cb5d
commit 64c19ba29b
7 changed files with 31 additions and 25 deletions
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15
include/asm-generic/syscall.h
View File

@ -43,7 +43,7 @@ int syscall_get_nr(struct task_struct *task, struct pt_regs *regs);
* @regs: task_pt_regs() of @task
*
* It's only valid to call this when @task is stopped for system
* call exit tracing (due to TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
* call exit tracing (due to %SYSCALL_WORK_SYSCALL_TRACE or TIF_SYSCALL_AUDIT),
* after tracehook_report_syscall_entry() returned nonzero to prevent
* the system call from taking place.
*
@ -63,7 +63,7 @@ void syscall_rollback(struct task_struct *task, struct pt_regs *regs);
* Returns 0 if the system call succeeded, or -ERRORCODE if it failed.
*
* It's only valid to call this when @task is stopped for tracing on exit
* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
*/
long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
@ -76,7 +76,7 @@ long syscall_get_error(struct task_struct *task, struct pt_regs *regs);
* This value is meaningless if syscall_get_error() returned nonzero.
*
* It's only valid to call this when @task is stopped for tracing on exit
* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
*/
long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
@ -93,7 +93,7 @@ long syscall_get_return_value(struct task_struct *task, struct pt_regs *regs);
* code; the user sees a failed system call with this errno code.
*
* It's only valid to call this when @task is stopped for tracing on exit
* from a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* from a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
*/
void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
int error, long val);
@ -108,7 +108,7 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
* @args[0], and so on.
*
* It's only valid to call this when @task is stopped for tracing on
* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
*/
void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
unsigned long *args);
@ -123,7 +123,7 @@ void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
* The first argument gets value @args[0], and so on.
*
* It's only valid to call this when @task is stopped for tracing on
* entry to a system call, due to %TIF_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
* entry to a system call, due to %SYSCALL_WORK_SYSCALL_TRACE or %TIF_SYSCALL_AUDIT.
*/
void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
const unsigned long *args);
@ -135,7 +135,8 @@ void syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
* Returns the AUDIT_ARCH_* based on the system call convention in use.
*
* It's only valid to call this when @task is stopped on entry to a system
* call, due to %TIF_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or %SYSCALL_WORK_SECCOMP.
* call, due to %SYSCALL_WORK_SYSCALL_TRACE, %TIF_SYSCALL_AUDIT, or
* %SYSCALL_WORK_SECCOMP.
*
* Architectures which permit CONFIG_HAVE_ARCH_SECCOMP_FILTER must
* provide an implementation of this.

10
include/linux/entry-common.h
View File

@ -41,7 +41,7 @@
#endif
#define SYSCALL_ENTER_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
(_TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_EMU | \
ARCH_SYSCALL_ENTER_WORK)
@ -53,12 +53,14 @@
#endif
#define SYSCALL_EXIT_WORK \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
(_TIF_SYSCALL_AUDIT | \
ARCH_SYSCALL_EXIT_WORK)
#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \
SYSCALL_WORK_SYSCALL_TRACEPOINT)
#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT)
SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE)
#define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \
SYSCALL_WORK_SYSCALL_TRACE)
/*
* TIF flags handled in exit_to_user_mode_loop()

2
include/linux/thread_info.h
View File

@ -38,10 +38,12 @@ enum {
enum syscall_work_bit {
SYSCALL_WORK_BIT_SECCOMP,
SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT,
SYSCALL_WORK_BIT_SYSCALL_TRACE,
};
#define SYSCALL_WORK_SECCOMP BIT(SYSCALL_WORK_BIT_SECCOMP)
#define SYSCALL_WORK_SYSCALL_TRACEPOINT BIT(SYSCALL_WORK_BIT_SYSCALL_TRACEPOINT)
#define SYSCALL_WORK_SYSCALL_TRACE BIT(SYSCALL_WORK_BIT_SYSCALL_TRACE)
#include <asm/thread_info.h>

17
include/linux/tracehook.h
View File

@ -83,11 +83,12 @@ static inline int ptrace_report_syscall(struct pt_regs *regs,
* tracehook_report_syscall_entry - task is about to attempt a system call
* @regs: user register state of current task
*
* This will be called if %TIF_SYSCALL_TRACE or %TIF_SYSCALL_EMU have been set,
* when the current task has just entered the kernel for a system call.
* Full user register state is available here. Changing the values
* in @regs can affect the system call number and arguments to be tried.
* It is safe to block here, preventing the system call from beginning.
* This will be called if %SYSCALL_WORK_SYSCALL_TRACE or
* %TIF_SYSCALL_EMU have been set, when the current task has just
* entered the kernel for a system call. Full user register state is
* available here. Changing the values in @regs can affect the system
* call number and arguments to be tried. It is safe to block here,
* preventing the system call from beginning.
*
* Returns zero normally, or nonzero if the calling arch code should abort
* the system call. That must prevent normal entry so no system call is
@ -109,15 +110,15 @@ static inline __must_check int tracehook_report_syscall_entry(
* @regs: user register state of current task
* @step: nonzero if simulating single-step or block-step
*
* This will be called if %TIF_SYSCALL_TRACE has been set, when the
* current task has just finished an attempted system call. Full
* This will be called if %SYSCALL_WORK_SYSCALL_TRACE has been set, when
* the current task has just finished an attempted system call. Full
* user register state is available here. It is safe to block here,
* preventing signals from being processed.
*
* If @step is nonzero, this report is also in lieu of the normal
* trap that would follow the system call instruction because
* user_enable_block_step() or user_enable_single_step() was used.
* In this case, %TIF_SYSCALL_TRACE might not be set.
* In this case, %SYSCALL_WORK_SYSCALL_TRACE might not be set.
*
* Called without locks, just before checking for pending signals.
*/

4
kernel/entry/common.c
View File

@ -47,7 +47,7 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
long ret = 0;
/* Handle ptrace */
if (ti_work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) {
if (work & SYSCALL_WORK_SYSCALL_TRACE || ti_work & _TIF_SYSCALL_EMU) {
ret = arch_syscall_enter_tracehook(regs);
if (ret || (ti_work & _TIF_SYSCALL_EMU))
return -1L;
@ -237,7 +237,7 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long ti_work,
trace_sys_exit(regs, syscall_get_return_value(current, regs));
step = report_single_step(ti_work);
if (step || ti_work & _TIF_SYSCALL_TRACE)
if (step || work & SYSCALL_WORK_SYSCALL_TRACE)
arch_syscall_exit_tracehook(regs, step);
}

2
kernel/fork.c
View File

@ -2158,7 +2158,7 @@ static __latent_entropy struct task_struct *copy_process(
* child regardless of CLONE_PTRACE.
*/
user_disable_single_step(p);
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
clear_task_syscall_work(p, SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
#endif

6
kernel/ptrace.c
View File

@ -117,7 +117,7 @@ void __ptrace_unlink(struct task_struct *child)
const struct cred *old_cred;
BUG_ON(!child->ptrace);
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
clear_task_syscall_work(child, SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
#endif
@ -812,9 +812,9 @@ static int ptrace_resume(struct task_struct *child, long request,
return -EIO;
if (request == PTRACE_SYSCALL)
set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
set_task_syscall_work(child, SYSCALL_TRACE);
else
clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
clear_task_syscall_work(child, SYSCALL_TRACE);
#ifdef TIF_SYSCALL_EMU
if (request == PTRACE_SYSEMU || request == PTRACE_SYSEMU_SINGLESTEP)