[PATCH 1/3] powerpc: asm/ppc-opcode.h: introduce __PPC_SH64()

[PATCH 1/3] powerpc: asm/ppc-opcode.h: introduce __PPC_SH64()

[Anju T Sudhakar]

From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>

Introduce __PPC_SH64() as a 64-bit variant to encode shift field in some
of the shift and rotate instructions operating on double-words. Convert
some of the BPF instruction macros to use the same.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/ppc-opcode.h |  1 +
 arch/powerpc/net/bpf_jit.h            | 11 +++++------
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 0132831..630127b 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -306,6 +306,7 @@
 #define __PPC_WC(w)	(((w) & 0x3) << 21)
 #define __PPC_WS(w)	(((w) & 0x1f) << 11)
 #define __PPC_SH(s)	__PPC_WS(s)
+#define __PPC_SH64(s)	(__PPC_SH(s) | (((s) & 0x20) >> 4))
 #define __PPC_MB(s)	(((s) & 0x1f) << 6)
 #define __PPC_ME(s)	(((s) & 0x1f) << 1)
 #define __PPC_MB64(s)	(__PPC_MB(s) | ((s) & 0x20))
diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
index 89f7007..30cf03f 100644
--- a/arch/powerpc/net/bpf_jit.h
+++ b/arch/powerpc/net/bpf_jit.h
@@ -157,8 +157,7 @@
 #define PPC_SRAD(d, a, s)	EMIT(PPC_INST_SRAD | ___PPC_RA(d) |	      \
 				     ___PPC_RS(a) | ___PPC_RB(s))
 #define PPC_SRADI(d, a, i)	EMIT(PPC_INST_SRADI | ___PPC_RA(d) |	      \
-				     ___PPC_RS(a) | __PPC_SH(i) |             \
-				     (((i) & 0x20) >> 4))
+				     ___PPC_RS(a) | __PPC_SH64(i))
 #define PPC_RLWINM(d, a, i, mb, me)	EMIT(PPC_INST_RLWINM | ___PPC_RA(d) | \
 					___PPC_RS(a) | __PPC_SH(i) |	      \
 					__PPC_MB(mb) | __PPC_ME(me))
@@ -166,11 +165,11 @@
 					___PPC_RS(a) | __PPC_SH(i) |	      \
 					__PPC_MB(mb) | __PPC_ME(me))
 #define PPC_RLDICL(d, a, i, mb)		EMIT(PPC_INST_RLDICL | ___PPC_RA(d) | \
-					___PPC_RS(a) | __PPC_SH(i) |	      \
-					__PPC_MB64(mb) | (((i) & 0x20) >> 4))
+					___PPC_RS(a) | __PPC_SH64(i) |	      \
+					__PPC_MB64(mb))
 #define PPC_RLDICR(d, a, i, me)		EMIT(PPC_INST_RLDICR | ___PPC_RA(d) | \
-					___PPC_RS(a) | __PPC_SH(i) |	      \
-					__PPC_ME64(me) | (((i) & 0x20) >> 4))
+					___PPC_RS(a) | __PPC_SH64(i) |	      \
+					__PPC_ME64(me))
 
 /* slwi = rlwinm Rx, Ry, n, 0, 31-n */
 #define PPC_SLWI(d, a, i)	PPC_RLWINM(d, a, i, 0, 31-(i))
-- 
2.7.4

[PATCH 2/3] powerpc: add helper to check if offset is within rel branch range

[Anju T Sudhakar]

To permit the use of relative branch instruction in powerpc, the target 
address has to be relatively nearby, since the address is specified in an 
immediate field (24 bit filed) in the instruction opcode itself. Here 
nearby refers to 32MB on either side of the current instruction.

This patch verifies whether the target address is within +/- 32MB
range or not.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/code-patching.h |  1 +
 arch/powerpc/lib/code-patching.c         | 24 +++++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 2015b07..75ee4f4 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -22,6 +22,7 @@
 #define BRANCH_SET_LINK	0x1
 #define BRANCH_ABSOLUTE	0x2
 
+bool is_offset_in_branch_range(long offset);
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags);
 unsigned int create_cond_branch(const unsigned int *addr,
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index d5edbeb..f643451 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -32,6 +32,28 @@ int patch_branch(unsigned int *addr, unsigned long target, int flags)
 	return patch_instruction(addr, create_branch(addr, target, flags));
 }
 
+bool is_offset_in_branch_range(long offset)
+{
+	/*
+	 * Powerpc branch instruction is :
+	 *
+	 *  0         6                 30   31
+	 *  +---------+----------------+---+---+
+	 *  | opcode  |     LI         |AA |LK |
+	 *  +---------+----------------+---+---+
+	 *  Where AA = 0 and LK = 0
+	 *
+	 * LI is a signed 24 bits integer. The real branch offset is computed
+	 * by: imm32 = SignExtend(LI:'0b00', 32);
+	 *
+	 * So the maximum forward branch should be:
+	 *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
+	 * The maximum backward branch should be:
+	 *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
+	 */
+	return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
+}
+
 unsigned int create_branch(const unsigned int *addr,
 			   unsigned long target, int flags)
 {
@@ -43,7 +65,7 @@ unsigned int create_branch(const unsigned int *addr,
 		offset = offset - (unsigned long)addr;
 
 	/* Check we can represent the target in the instruction format */
-	if (offset < -0x2000000 || offset > 0x1fffffc || offset & 0x3)
+	if (!is_offset_in_branch_range(offset))
 		return 0;
 
 	/* Mask out the flags and target, so they don't step on each other. */
-- 
2.7.4

[PATCH 3/3] powerpc: kprobes: fixes for kprobe_lookup_name on BE

[Anju T Sudhakar]

From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>

Fix two issues with kprobes.h on BE which were exposed with the optprobes work:
- one, having to do with a missing include for linux/module.h for
MODULE_NAME_LEN -- this didn't show up previously since the only users of
kprobe_lookup_name were in kprobes.c, which included linux/module.h
through other headers, and
- two, with a missing const qualifier for a local variable which ends up
referring a string literal. Again, this is unique to how
kprobe_lookup_name is being invoked in optprobes.c

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/kprobes.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
index 97b8c1f..77885d8 100644
--- a/arch/powerpc/include/asm/kprobes.h
+++ b/arch/powerpc/include/asm/kprobes.h
@@ -29,6 +29,7 @@
 #include <linux/types.h>
 #include <linux/ptrace.h>
 #include <linux/percpu.h>
+#include <linux/module.h>
 #include <asm/probes.h>
 #include <asm/code-patching.h>
 
@@ -61,7 +62,7 @@ typedef ppc_opcode_t kprobe_opcode_t;
 #define kprobe_lookup_name(name, addr)					\
 {									\
 	char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];		\
-	char *modsym;							\
+	const char *modsym;							\
 	bool dot_appended = false;					\
 	if ((modsym = strchr(name, ':')) != NULL) {			\
 		modsym++;						\
-- 
2.7.4

Re: [1/3] powerpc: asm/ppc-opcode.h: introduce __PPC_SH64()

[Michael Ellerman]

On Wed, 2017-02-08 at 08:57:29 UTC, Anju T wrote:
> From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
> 
> Introduce __PPC_SH64() as a 64-bit variant to encode shift field in some
> of the shift and rotate instructions operating on double-words. Convert
> some of the BPF instruction macros to use the same.
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Series applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/c233f5979b3dbb39a5b2473b5fcaf5

cheers