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authorNicolas Pitre <nicolas.pitre@linaro.org>2017-07-28 15:35:35 -0400
committerNicolas Pitre <nicolas.pitre@linaro.org>2017-09-10 19:31:46 -0400
commit8fcd6c45f5a65621ec809b7866a3623e9a01d4ed (patch)
tree2e6eea80b386c293d20e5bb813b8b70bff78baf1
parentLinux 4.13 (diff)
downloadlinux-dev-8fcd6c45f5a65621ec809b7866a3623e9a01d4ed.tar.xz
linux-dev-8fcd6c45f5a65621ec809b7866a3623e9a01d4ed.zip
ARM: implement get_tls syscall
When there is no dedicated register to hold the tp value and no MMU to provide a fixed address kuser helper entry point, all that is left as fallback is a syscall. Signed-off-by: Nicolas Pitre <nico@linaro.org> Acked-by: Mickael GUENE <mickael.guene@st.com> Tested-by: Vincent Abriou <vincent.abriou@st.com> Tested-by: Andras Szemzo <szemzo.andras@gmail.com>
-rw-r--r--arch/arm/include/uapi/asm/unistd.h1
-rw-r--r--arch/arm/kernel/traps.c3
2 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm/include/uapi/asm/unistd.h b/arch/arm/include/uapi/asm/unistd.h
index 28bd456494a3..575b25fc29c6 100644
--- a/arch/arm/include/uapi/asm/unistd.h
+++ b/arch/arm/include/uapi/asm/unistd.h
@@ -35,5 +35,6 @@
#define __ARM_NR_usr26 (__ARM_NR_BASE+3)
#define __ARM_NR_usr32 (__ARM_NR_BASE+4)
#define __ARM_NR_set_tls (__ARM_NR_BASE+5)
+#define __ARM_NR_get_tls (__ARM_NR_BASE+6)
#endif /* _UAPI__ASM_ARM_UNISTD_H */
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 948c648fea00..43c0560f7b2d 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -647,6 +647,9 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
set_tls(regs->ARM_r0);
return 0;
+ case NR(get_tls):
+ return current_thread_info()->tp_value[0];
+
default:
/* Calls 9f00xx..9f07ff are defined to return -ENOSYS
if not implemented, rather than raising SIGILL. This