powerpc/livepatch: Add livepatch stack to struct thread_info

In order to support live patching we need to maintain an alternate
stack of TOC & LR values. We use the base of the stack for this, and
store the "live patch stack pointer" in struct thread_info.

Unlike the other fields of thread_info, we can not statically initialise
that value, so it must be done at run time.

This patch just adds the code to support that, it is not enabled until
the next patch which actually adds live patch support.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Balbir Singh <bsingharora@gmail.com>

diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h
index ad36e8e34fa135632d5e71452826b49e4308f1aa..a402f7f948965f1f28d4c3f2385001c1ecdef2b6 100644 (file)
--- a/arch/powerpc/include/asm/livepatch.h
+++ b/arch/powerpc/include/asm/livepatch.h
@@ -49,6 +49,14 @@ static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
         */
        return ftrace_location_range(faddr, faddr + 16);
 }
+
+static inline void klp_init_thread_info(struct thread_info *ti)
+{
+       /* + 1 to account for STACK_END_MAGIC */
+       ti->livepatch_sp = (unsigned long *)(ti + 1) + 1;
+}
+#else
+static void klp_init_thread_info(struct thread_info *ti) { }
 #endif /* CONFIG_LIVEPATCH */
 
 #endif /* _ASM_POWERPC_LIVEPATCH_H */

diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 7efee4a3240ba291481ccf135725fc8371cdcbee..8febc3f66d53056a3bdc0ffbf9b81757eb14d605 100644 (file)
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -43,7 +43,9 @@ struct thread_info {
        int             preempt_count;          /* 0 => preemptable,
                                                   <0 => BUG */
        unsigned long   local_flags;            /* private flags for thread */
-
+#ifdef CONFIG_LIVEPATCH
+       unsigned long *livepatch_sp;
+#endif
        /* low level flags - has atomic operations done on it */
        unsigned long   flags ____cacheline_aligned_in_smp;
 };

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 290559df1e8b305d941ab52d7022a818b92ee8b8..3cb46a3b1de78bcf2d84298130e49e5a73414073 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -66,6 +66,7 @@
 #include <asm/udbg.h>
 #include <asm/smp.h>
 #include <asm/debug.h>
+#include <asm/livepatch.h>
 
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
@@ -607,10 +608,12 @@ void irq_ctx_init(void)
                memset((void *)softirq_ctx[i], 0, THREAD_SIZE);
                tp = softirq_ctx[i];
                tp->cpu = i;
+               klp_init_thread_info(tp);
 
                memset((void *)hardirq_ctx[i], 0, THREAD_SIZE);
                tp = hardirq_ctx[i];
                tp->cpu = i;
+               klp_init_thread_info(tp);
        }
 }
 

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index dccc87e8fee5e6544de0d8fc732a97aa14f45907..a38ce49648cb76e5bf184291ce5b73f11551314d 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -55,6 +55,8 @@
 #include <asm/firmware.h>
 #endif
 #include <asm/code-patching.h>
+#include <asm/livepatch.h>
+
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
 
@@ -1267,13 +1269,15 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
        extern void ret_from_kernel_thread(void);
        void (*f)(void);
        unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+       struct thread_info *ti = task_thread_info(p);
+
+       klp_init_thread_info(ti);
 
        /* Copy registers */
        sp -= sizeof(struct pt_regs);
        childregs = (struct pt_regs *) sp;
        if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
-               struct thread_info *ti = (void *)task_stack_page(p);
                memset(childregs, 0, sizeof(struct pt_regs));
                childregs->gpr[1] = sp + sizeof(struct pt_regs);
                /* function */

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5c03a6a9b0542fac3d042f2481f367aae9178d38..e37b92ebb3157335bb513eb6f04918edfc7de447 100644 (file)
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -69,6 +69,7 @@
 #include <asm/kvm_ppc.h>
 #include <asm/hugetlb.h>
 #include <asm/epapr_hcalls.h>
+#include <asm/livepatch.h>
 
 #ifdef DEBUG
 #define DBG(fmt...) udbg_printf(fmt)
@@ -670,16 +671,16 @@ static void __init emergency_stack_init(void)
        limit = min(safe_stack_limit(), ppc64_rma_size);
 
        for_each_possible_cpu(i) {
-               unsigned long sp;
-               sp  = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit);
-               sp += THREAD_SIZE;
-               paca[i].emergency_sp = __va(sp);
+               struct thread_info *ti;
+               ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit));
+               klp_init_thread_info(ti);
+               paca[i].emergency_sp = (void *)ti + THREAD_SIZE;
 
 #ifdef CONFIG_PPC_BOOK3S_64
                /* emergency stack for machine check exception handling. */
-               sp  = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit);
-               sp += THREAD_SIZE;
-               paca[i].mc_emergency_sp = __va(sp);
+               ti = __va(memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit));
+               klp_init_thread_info(ti);
+               paca[i].mc_emergency_sp = (void *)ti + THREAD_SIZE;
 #endif
        }
 }
@@ -703,6 +704,8 @@ void __init setup_arch(char **cmdline_p)
        if (ppc_md.panic)
                setup_panic();
 
+       klp_init_thread_info(&init_thread_info);
+
        init_mm.start_code = (unsigned long)_stext;
        init_mm.end_code = (unsigned long) _etext;
        init_mm.end_data = (unsigned long) _edata;