[ORLinux] [PATCH 2/2] openrisc: Add thread-local storage (TLS) support

[Christian Svensson]

Historically OpenRISC GCC has reserved r10 which we now use to hold
the thread pointer for thread-local storage (TLS).

Signed-off-by: Christian Svensson <blue at cmd.nu>
---
arch/openrisc/kernel/process.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 386af25..86b9978 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -173,6 +173,19 @@ copy_thread(unsigned long clone_flags, unsigned long
usp,

if (usp)
userregs->sp = usp;
+
+ /*
+ * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
+ *
+ * The kernel entry is:
+ * int clone (long flags, void *child_stack, int *parent_tid,
+ * int *child_tid, struct void *tls)
+ *
+ * This makes the source r7 in the kernel registers.
+ */
+ if (clone_flags & CLONE_SETTLS)
+ userregs->gpr[10] = kregs->gpr[7];
+
userregs->gpr[11] = 0; /* Result from fork() */

kregs->gpr[20] = 0; /* Userspace thread */
--
1.7.10.4
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[Christian Svensson]

Ping!

Post by Christian Svensson
Historically OpenRISC GCC has reserved r10 which we now use to hold
the thread pointer for thread-local storage (TLS).
Signed-off-by: Christian Svensson <blue at cmd.nu>
---
arch/openrisc/kernel/process.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 386af25..86b9978 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -173,6 +173,19 @@ copy_thread(unsigned long clone_flags, unsigned long
usp,
if (usp)
userregs->sp = usp;
+
+ /*
+ * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
+ *
+ * int clone (long flags, void *child_stack, int *parent_tid,
+ * int *child_tid, struct void *tls)
+ *
+ * This makes the source r7 in the kernel registers.
+ */
+ if (clone_flags & CLONE_SETTLS)
+ userregs->gpr[10] = kregs->gpr[7];
+
userregs->gpr[11] = 0; /* Result from fork() */
kregs->gpr[20] = 0; /* Userspace thread */
--
1.7.10.4

[Stefan Kristiansson]

Post by Christian Svensson
Historically OpenRISC GCC has reserved r10 which we now use to hold
the thread pointer for thread-local storage (TLS).
Signed-off-by: Christian Svensson <blue at cmd.nu>
---
arch/openrisc/kernel/process.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 386af25..86b9978 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -173,6 +173,19 @@ copy_thread(unsigned long clone_flags, unsigned long
usp,
if (usp)
userregs->sp = usp;
+
+ /*
+ * For CLONE_SETTLS set "tp" (r10) to the TLS pointer passed to sys_clone.
+ *
+ * int clone (long flags, void *child_stack, int *parent_tid,
+ * int *child_tid, struct void *tls)
+ *
+ * This makes the source r7 in the kernel registers.
+ */
+ if (clone_flags & CLONE_SETTLS)
+ userregs->gpr[10] = kregs->gpr[7];

To keep it on record so we don't forget it, this should be:

userregs->gpr[10] = userregs->gpr[7];

Post by Christian Svensson
+
userregs->gpr[11] = 0; /* Result from fork() */
kregs->gpr[20] = 0; /* Userspace thread */
--
1.7.10.4
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[Christian Svensson]

Updated patch.
Since I'm sending this via gmail I do not expect the patch to be
copy-paste:able so I attached it. The patch is also viewable at:
https://github.com/bluecmd/or1k-linux/commit/5407ab8ce13f2c3f85e733c5d6b5cca5fb35f728.patch