Subject: [to-be-updated] s390-kprobes-add-support-for-pc-relative-long-displacement-instructions.patch removed from -mm tree
To: heiko.carstens@xxxxxxxxxx,ananth@xxxxxxxxxx,masami.hiramatsu.pt@xxxxxxxxxxx,mingo@xxxxxxxxxx,schwidefsky@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 23 Aug 2013 15:39:20 -0700
The patch titled
Subject: s390/kprobes: add support for pc-relative long displacement instructions
has been removed from the -mm tree. Its filename was
s390-kprobes-add-support-for-pc-relative-long-displacement-instructions.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Subject: s390/kprobes: add support for pc-relative long displacement instructions
With the general-instruction extension facility (z10) a couple of
instructions with a pc-relative long displacement were introduced. The
kprobes support for these instructions however was never implemented.
In result, if anybody ever put a probe on any of these instructions the
result would have been random behaviour after the instruction got executed
within the insn slot.
So lets add the missing handling for these instructions. Since all of the
new instructions have 32 bit signed displacement the easiest solution is
to allocate an insn slot that is within the same 2GB area like the
original instruction and patch the displacement field.
Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/s390/Kconfig | 1
arch/s390/include/asm/kprobes.h | 4
arch/s390/kernel/kprobes.c | 124 ++++++++++++++++++++++++++++--
3 files changed, 121 insertions(+), 8 deletions(-)
diff -puN arch/s390/Kconfig~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions arch/s390/Kconfig
--- a/arch/s390/Kconfig~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions
+++ a/arch/s390/Kconfig
@@ -96,6 +96,7 @@ config S390
select ARCH_WANT_IPC_PARSE_VERSION
select BUILDTIME_EXTABLE_SORT
select CLONE_BACKWARDS2
+ select DMAPROBES if KPROBES
select GENERIC_CLOCKEVENTS
select GENERIC_CPU_DEVICES if !SMP
select GENERIC_SMP_IDLE_THREAD
diff -puN arch/s390/include/asm/kprobes.h~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions arch/s390/include/asm/kprobes.h
--- a/arch/s390/include/asm/kprobes.h~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions
+++ a/arch/s390/include/asm/kprobes.h
@@ -31,6 +31,8 @@
#include <linux/ptrace.h>
#include <linux/percpu.h>
+#define __ARCH_WANT_KPROBES_INSN_SLOT
+
struct pt_regs;
struct kprobe;
@@ -57,7 +59,7 @@ typedef u16 kprobe_opcode_t;
/* Architecture specific copy of original instruction */
struct arch_specific_insn {
/* copy of original instruction */
- kprobe_opcode_t insn[MAX_INSN_SIZE];
+ kprobe_opcode_t *insn;
};
struct prev_kprobe {
diff -puN arch/s390/kernel/kprobes.c~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions arch/s390/kernel/kprobes.c
--- a/arch/s390/kernel/kprobes.c~s390-kprobes-add-support-for-pc-relative-long-displacement-instructions
+++ a/arch/s390/kernel/kprobes.c
@@ -100,9 +100,8 @@ static int __kprobes get_fixup_type(kpro
fixup |= FIXUP_RETURN_REGISTER;
break;
case 0xc0:
- if ((insn[0] & 0x0f) == 0x00 || /* larl */
- (insn[0] & 0x0f) == 0x05) /* brasl */
- fixup |= FIXUP_RETURN_REGISTER;
+ if ((insn[0] & 0x0f) == 0x05) /* brasl */
+ fixup |= FIXUP_RETURN_REGISTER;
break;
case 0xeb:
if ((insn[2] & 0xff) == 0x44 || /* bxhg */
@@ -117,18 +116,128 @@ static int __kprobes get_fixup_type(kpro
return fixup;
}
+static int __kprobes is_insn_relative_long(kprobe_opcode_t *insn)
+{
+ /* Check if we have a RIL-b or RIL-c format instruction which
+ * we need to modify in order to avoid instruction emulation. */
+ switch (insn[0] >> 8) {
+ case 0xc0:
+ if ((insn[0] & 0x0f) == 0x00) /* larl */
+ return true;
+ break;
+ case 0xc4:
+ switch (insn[0] & 0x0f) {
+ case 0x02: /* llhrl */
+ case 0x04: /* lghrl */
+ case 0x05: /* lhrl */
+ case 0x06: /* llghrl */
+ case 0x07: /* sthrl */
+ case 0x08: /* lgrl */
+ case 0x0b: /* stgrl */
+ case 0x0c: /* lgfrl */
+ case 0x0d: /* lrl */
+ case 0x0e: /* llgfrl */
+ case 0x0f: /* strl */
+ return true;
+ }
+ break;
+ case 0xc6:
+ switch (insn[0] & 0x0f) {
+ case 0x00: /* exrl */
+ case 0x02: /* pfdrl */
+ case 0x04: /* cghrl */
+ case 0x05: /* chrl */
+ case 0x06: /* clghrl */
+ case 0x07: /* clhrl */
+ case 0x08: /* cgrl */
+ case 0x0a: /* clgrl */
+ case 0x0c: /* cgfrl */
+ case 0x0d: /* crl */
+ case 0x0e: /* clgfrl */
+ case 0x0f: /* clrl */
+ return true;
+ }
+ break;
+ }
+ return false;
+}
+
+static void __kprobes copy_instruction(struct kprobe *p)
+{
+ s64 disp, new_disp;
+ u64 addr, new_addr;
+
+ memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2);
+ if (!is_insn_relative_long(p->ainsn.insn))
+ return;
+ /*
+ * For pc-relative instructions in RIL-b or RIL-c format patch the
+ * RI2 displacement field. We have already made sure that the insn
+ * slot for the patched instruction is within the same 2GB area
+ * as the original instruction (either kernel image or module area).
+ * Therefore the new displacement will always fit.
+ */
+ disp = *(s32 *)&p->ainsn.insn[1];
+ addr = (u64)(unsigned long)p->addr;
+ new_addr = (u64)(unsigned long)p->ainsn.insn;
+ new_disp = ((addr + (disp * 2)) - new_addr) / 2;
+ *(s32 *)&p->ainsn.insn[1] = new_disp;
+}
+
+static inline int is_kernel_addr(void *addr)
+{
+ return addr < (void *)_end;
+}
+
+static inline int is_module_addr(void *addr)
+{
+#ifdef CONFIG_64BIT
+ BUILD_BUG_ON(MODULES_LEN > (1UL << 31));
+ if (addr < (void *)MODULES_VADDR)
+ return 0;
+ if (addr > (void *)MODULES_END)
+ return 0;
+#endif
+ return 1;
+}
+
+static int __kprobes s390_get_insn_slot(struct kprobe *p)
+{
+ /*
+ * Get an insn slot that is within the same 2GB area like the original
+ * instruction. That way instructions with a 32bit signed displacement
+ * field can be patched and executed within the insn slot.
+ */
+ p->ainsn.insn = NULL;
+ if (is_kernel_addr(p->addr))
+ p->ainsn.insn = get_dmainsn_slot();
+ if (is_module_addr(p->addr))
+ p->ainsn.insn = get_insn_slot();
+ return p->ainsn.insn ? 0 : -ENOMEM;
+}
+
+static void __kprobes s390_free_insn_slot(struct kprobe *p)
+{
+ if (!p->ainsn.insn)
+ return;
+ if (is_kernel_addr(p->addr))
+ free_dmainsn_slot(p->ainsn.insn, 0);
+ else
+ free_insn_slot(p->ainsn.insn, 0);
+ p->ainsn.insn = NULL;
+}
+
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
if ((unsigned long) p->addr & 0x01)
return -EINVAL;
-
/* Make sure the probe isn't going on a difficult instruction */
if (is_prohibited_opcode(p->addr))
return -EINVAL;
-
+ if (s390_get_insn_slot(p))
+ return -ENOMEM;
p->opcode = *p->addr;
- memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2);
-
+ copy_instruction(p);
return 0;
}
@@ -169,6 +278,7 @@ void __kprobes arch_disarm_kprobe(struct
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
+ s390_free_insn_slot(p);
}
static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb,
_
Patches currently in -mm which might be from heiko.carstens@xxxxxxxxxx are
linux-next.patch
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