Commit c50842df authored by Chris Zankel's avatar Chris Zankel
Browse files

xtensa: add support for TLS



The Xtensa architecture provides a global register called THREADPTR
for the purpose of Thread Local Storage (TLS) support. This allows us
to use a fairly simple implementation, keeping the thread pointer in
the regset and simply saving and restoring it upon entering/exiting
the from user space.

Signed-off-by: default avatarChris Zankel <chris@zankel.net>
parent b0c438e6
......@@ -84,7 +84,8 @@ typedef struct {
elf_greg_t sar;
elf_greg_t windowstart;
elf_greg_t windowbase;
elf_greg_t reserved[8+48];
elf_greg_t threadptr;
elf_greg_t reserved[7+48];
elf_greg_t a[64];
} xtensa_gregset_t;
......
......@@ -38,6 +38,7 @@ struct pt_regs {
unsigned long syscall; /* 56 */
unsigned long icountlevel; /* 60 */
unsigned long scompare1; /* 64 */
unsigned long threadptr; /* 68 */
/* Additional configurable registers that are used by the compiler. */
xtregs_opt_t xtregs_opt;
......@@ -48,7 +49,7 @@ struct pt_regs {
/* current register frame.
* Note: The ESF for kernel exceptions ends after 16 registers!
*/
unsigned long areg[16]; /* 128 (64) */
unsigned long areg[16];
};
#include <variant/core.h>
......
......@@ -42,6 +42,7 @@ int main(void)
DEFINE(PT_ICOUNTLEVEL, offsetof (struct pt_regs, icountlevel));
DEFINE(PT_SYSCALL, offsetof (struct pt_regs, syscall));
DEFINE(PT_SCOMPARE1, offsetof(struct pt_regs, scompare1));
DEFINE(PT_THREADPTR, offsetof(struct pt_regs, threadptr));
DEFINE(PT_AREG, offsetof (struct pt_regs, areg[0]));
DEFINE(PT_AREG0, offsetof (struct pt_regs, areg[0]));
DEFINE(PT_AREG1, offsetof (struct pt_regs, areg[1]));
......
......@@ -130,6 +130,11 @@ _user_exception:
s32i a3, a1, PT_SAR
s32i a2, a1, PT_ICOUNTLEVEL
#if XCHAL_HAVE_THREADPTR
rur a2, threadptr
s32i a2, a1, PT_THREADPTR
#endif
/* Rotate ws so that the current windowbase is at bit0. */
/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
......@@ -510,6 +515,11 @@ user_exception_exit:
* (if we have restored WSBITS-1 frames).
*/
#if XCHAL_HAVE_THREADPTR
l32i a3, a1, PT_THREADPTR
wur a3, threadptr
#endif
2: j common_exception_exit
/* This is the kernel exception exit.
......@@ -1955,7 +1965,7 @@ ENTRY(_switch_to)
s32i a6, a3, EXC_TABLE_FIXUP
s32i a7, a3, EXC_TABLE_KSTK
/* restore context of the task that 'next' addresses */
/* restore context of the task 'next' */
l32i a0, a13, THREAD_RA # restore return address
l32i a1, a13, THREAD_SP # restore stack pointer
......
......@@ -259,9 +259,10 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
&regs->areg[XCHAL_NUM_AREGS - len/4], len);
}
// FIXME: we need to set THREADPTR in thread_info...
/* The thread pointer is passed in the '4th argument' (= a5) */
if (clone_flags & CLONE_SETTLS)
childregs->areg[2] = childregs->areg[6];
childregs->threadptr = childregs->areg[5];
} else {
p->thread.ra = MAKE_RA_FOR_CALL(
(unsigned long)ret_from_kernel_thread, 1);
......
......@@ -66,6 +66,7 @@ int ptrace_getregs(struct task_struct *child, void __user *uregs)
__put_user(regs->lcount, &gregset->lcount);
__put_user(regs->windowstart, &gregset->windowstart);
__put_user(regs->windowbase, &gregset->windowbase);
__put_user(regs->threadptr, &gregset->threadptr);
for (i = 0; i < XCHAL_NUM_AREGS; i++)
__put_user(regs->areg[i],
......@@ -92,6 +93,7 @@ int ptrace_setregs(struct task_struct *child, void __user *uregs)
__get_user(regs->lcount, &gregset->lcount);
__get_user(ws, &gregset->windowstart);
__get_user(wb, &gregset->windowbase);
__get_user(regs->threadptr, &gregset->threadptr);
regs->ps = (regs->ps & ~ps_mask) | (ps & ps_mask) | (1 << PS_EXCM_BIT);
......
......@@ -337,7 +337,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
struct rt_sigframe *frame;
int err = 0;
int signal;
unsigned long sp, ra;
unsigned long sp, ra, tp;
sp = regs->areg[1];
......@@ -395,7 +395,8 @@ static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
* Return context not modified until this point.
*/
/* Set up registers for signal handler */
/* Set up registers for signal handler; preserve the threadptr */
tp = regs->threadptr;
start_thread(regs, (unsigned long) ka->sa.sa_handler,
(unsigned long) frame);
......@@ -406,6 +407,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
regs->areg[6] = (unsigned long) signal;
regs->areg[7] = (unsigned long) &frame->info;
regs->areg[8] = (unsigned long) &frame->uc;
regs->threadptr = tp;
/* Set access mode to USER_DS. Nomenclature is outdated, but
* functionality is used in uaccess.h
......
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