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Subject[PATCH 3/5] uprobes: introduce uprobe_xol_slots[NR_CPUS]
This patch adds uprobe_xol_slots[UPROBES_XOL_SLOT_BYTES][NR_CPUS] array.
Each CPU has its own slot for xol (used in the next patch).

We "export" this data to the user-space via set_fixmap(PAGE_KERNEL_VSYSCALL).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
arch/x86/include/asm/fixmap.h | 9 +++++++++
arch/x86/kernel/uprobes.c | 10 ++++++++++
include/linux/uprobes.h | 1 +
kernel/uprobes.c | 4 ++++
4 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 460c74e..a902e19 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/arch/x86/include/asm/fixmap.h
@@ -81,6 +81,15 @@ enum fixed_addresses {
VVAR_PAGE,
VSYSCALL_HPET,
#endif
+
+#ifdef CONFIG_UPROBES
+ #define UPROBES_XOL_SLOT_BYTES 128
+
+ UPROBE_XOL_LAST_PAGE,
+ UPROBE_XOL_FIRST_PAGE = UPROBE_XOL_LAST_PAGE
+ + NR_CPUS * UPROBES_XOL_SLOT_BYTES / PAGE_SIZE,
+#endif
+
FIX_DBGP_BASE,
FIX_EARLYCON_MEM_BASE,
#ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 4140137..ebb280c 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -664,3 +664,13 @@ bool can_skip_xol(struct pt_regs *regs, struct uprobe *u)
u->flags &= ~UPROBES_SKIP_SSTEP;
return false;
}
+
+void __init map_uprobe_xol_slots(void *pages)
+{
+ int idx = UPROBE_XOL_FIRST_PAGE;
+
+ do {
+ __set_fixmap(idx, __pa(pages), PAGE_KERNEL_VSYSCALL);
+ pages += PAGE_SIZE;
+ } while (idx-- != UPROBE_XOL_LAST_PAGE);
+}
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index d590d66..bb59a66 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -142,6 +142,7 @@ extern bool uprobe_deny_signal(void);
extern bool __weak can_skip_xol(struct pt_regs *regs, struct uprobe *u);
extern void __weak set_xol_ip(struct pt_regs *regs);
extern void uprobe_switch_to(struct task_struct *);
+extern void map_uprobe_xol_slots(void *);
#else /* CONFIG_UPROBES is not defined */
static inline int register_uprobe(struct inode *inode, loff_t offset,
struct uprobe_consumer *consumer)
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 9c509dc..20007da 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -1342,6 +1342,9 @@ bool __weak can_skip_xol(struct pt_regs *regs, struct uprobe *u)
return false;
}

+static unsigned char
+uprobe_xol_slots[UPROBES_XOL_SLOT_BYTES][NR_CPUS] __page_aligned_bss;
+
void __weak set_xol_ip(struct pt_regs *regs)
{
set_instruction_pointer(regs, current->utask->xol_vaddr);
@@ -1490,6 +1493,7 @@ static int __init init_uprobes(void)
mutex_init(&uprobes_mmap_mutex[i]);
}
init_bulkref(&uprobes_srcu);
+ map_uprobe_xol_slots(uprobe_xol_slots);
return register_die_notifier(&uprobe_exception_nb);
}

--
1.5.5.1



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