[RESEND PATCH v4 4/8] arm64: Separate in_compat_syscall from is_compat_task

Amanieu d'Antras
2021-05-18T09:08:08Z

This is preliminary work for allowing 64-bit processes to invoke compat
syscalls.

Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Co-developed-by: Ryan Houdek <Houdek.Ryan@fex-emu.org>
Signed-off-by: Ryan Houdek <Houdek.Ryan@fex-emu.org>
---
arch/arm64/include/asm/compat.h | 24 ++++++++++++++++++++----
arch/arm64/include/asm/ftrace.h | 2 +-
arch/arm64/include/asm/syscall.h | 6 +++---
arch/arm64/kernel/ptrace.c | 2 +-
arch/arm64/kernel/syscall.c | 2 +-
5 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
index 23a9fb73c04f..a2f5001f7793 100644
--- a/arch/arm64/include/asm/compat.h
+++ b/arch/arm64/include/asm/compat.h
@@ -178,21 +178,37 @@ struct compat_shmid64_ds {
compat_ulong_t __unused5;
};

-static inline int is_compat_task(void)
+static inline bool is_compat_task(void)
{
return test_thread_flag(TIF_32BIT);
}

-static inline int is_compat_thread(struct thread_info *thread)
+static inline bool is_compat_thread(struct thread_info *thread)
{
return test_ti_thread_flag(thread, TIF_32BIT);
}

+static inline bool in_compat_syscall(void)
+{
+ return is_compat_task();
+}
+#define in_compat_syscall in_compat_syscall /* override the generic impl */
+
+static inline bool thread_in_compat_syscall(struct thread_info *thread)
+{
+ return is_compat_thread(thread);
+}
+
#else /* !CONFIG_COMPAT */

-static inline int is_compat_thread(struct thread_info *thread)
+static inline bool is_compat_thread(struct thread_info *thread)
+{
+ return false;
+}
+
+static inline bool thread_in_compat_syscall(struct thread_info *thread)
{
- return 0;
+ return false;
}

#endif /* CONFIG_COMPAT */
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 91fa4baa1a93..f41aad92c67a 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -88,7 +88,7 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
{
- return is_compat_task();
+ return in_compat_syscall();
}

#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h
index cfc0672013f6..0dfc01ea386c 100644
--- a/arch/arm64/include/asm/syscall.h
+++ b/arch/arm64/include/asm/syscall.h
@@ -35,7 +35,7 @@ static inline long syscall_get_error(struct task_struct *task,
{
unsigned long error = regs->regs[0];

- if (is_compat_thread(task_thread_info(task)))
+ if (thread_in_compat_syscall(task_thread_info(task)))
error = sign_extend64(error, 31);

return IS_ERR_VALUE(error) ? error : 0;
@@ -54,7 +54,7 @@ static inline void syscall_set_return_value(struct task_struct *task,
if (error)
val = error;

- if (is_compat_thread(task_thread_info(task)))
+ if (thread_in_compat_syscall(task_thread_info(task)))
val = lower_32_bits(val);

regs->regs[0] = val;
@@ -88,7 +88,7 @@ static inline void syscall_set_arguments(struct task_struct *task,
*/
static inline int syscall_get_arch(struct task_struct *task)
{
- if (is_compat_thread(task_thread_info(task)))
+ if (thread_in_compat_syscall(task_thread_info(task)))
return AUDIT_ARCH_ARM;

return AUDIT_ARCH_AARCH64;
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 170f42fd6101..017a82b24f49 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1721,7 +1721,7 @@ const struct user_regset_view *task_user_regset_view(struct task_struct *task)
* 32-bit children use an extended user_aarch32_ptrace_view to allow
* access to the TLS register.
*/
- if (is_compat_task())
+ if (in_compat_syscall())
return &user_aarch32_view;
else if (is_compat_thread(task_thread_info(task)))
return &user_aarch32_ptrace_view;
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index b9cf12b271d7..e0e9d54de0a2 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -51,7 +51,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
ret = do_ni_syscall(regs, scno);
}

- if (is_compat_task())
+ if (in_compat_syscall())
ret = lower_32_bits(ret);

regs->regs[0] = ret;
--
2.31.1