[RESEND PATCH v4 6/8] arm64: Add a compat syscall flag to thread_info

Amanieu d'Antras
2021-05-18T09:08:09Z

This flag is used by in_compat_syscall to handle compat syscalls coming
from 64-bit tasks.

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 | 4 ++--
arch/arm64/include/asm/elf.h | 13 ++++++++++++-
arch/arm64/include/asm/thread_info.h | 6 ++++++
3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
index a2f5001f7793..124f4487dfee 100644
--- a/arch/arm64/include/asm/compat.h
+++ b/arch/arm64/include/asm/compat.h
@@ -190,13 +190,13 @@ static inline bool is_compat_thread(struct thread_info *thread)

static inline bool in_compat_syscall(void)
{
- return is_compat_task();
+ return current_thread_info()->use_compat_syscall;
}
#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);
+ return thread->use_compat_syscall;
}

#else /* !CONFIG_COMPAT */
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index e21964898d06..49a9a9db612c 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -158,10 +158,20 @@ typedef struct user_fpsimd_state elf_fpregset_t;
*/
#define ELF_PLAT_INIT(_r, load_addr) (_r)->regs[0] = 0

+#ifdef CONFIG_COMPAT
+#define CLEAR_COMPAT_SYSCALL() \
+({ \
+ current_thread_info()->use_compat_syscall = false; \
+})
+#else
+#define CLEAR_COMPAT_SYSCALL() ((void)0)
+#endif
+
#define SET_PERSONALITY(ex) \
({ \
clear_thread_flag(TIF_32BIT); \
current->personality &= ~READ_IMPLIES_EXEC; \
+ CLEAR_COMPAT_SYSCALL(); \
})

/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
@@ -228,7 +238,8 @@ typedef compat_elf_greg_t compat_elf_gregset_t[COMPAT_ELF_NGREG];
#define COMPAT_SET_PERSONALITY(ex) \
({ \
set_thread_flag(TIF_32BIT); \
- })
+ current_thread_info()->use_compat_syscall = true; \
+})
#ifdef CONFIG_COMPAT_VDSO
#define COMPAT_ARCH_DLINFO \
do { \
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 6623c99f0984..02310b45900d 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -42,6 +42,12 @@ struct thread_info {
void *scs_base;
void *scs_sp;
#endif
+#ifdef CONFIG_COMPAT
+ /*
+ * compat task or inside a compat syscall from a 64-bit task
+ */
+ bool use_compat_syscall;
+#endif
};

#define thread_saved_pc(tsk) \
--
2.31.1