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Message-Id: <1400666396-1682-9-git-send-email-khandual@linux.vnet.ibm.com>
Date: Wed, 21 May 2014 15:29:53 +0530
From: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To: peterz@...radead.org
Cc: linux-kernel@...r.kernel.org, mpe@...erman.id.au,
benh@...nel.crashing.org
Subject: [V6 08/11] powerpc, lib: Add new branch analysis support functions
Generic powerpc branch analysis support added in the code patching
library which will help the subsequent patch on SW based filtering
of branch records in perf.
Signed-off-by: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
---
arch/powerpc/include/asm/code-patching.h | 16 +++++++
arch/powerpc/lib/code-patching.c | 80 ++++++++++++++++++++++++++++++++
2 files changed, 96 insertions(+)
diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 97e02f9..39919d4 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -22,6 +22,16 @@
#define BRANCH_SET_LINK 0x1
#define BRANCH_ABSOLUTE 0x2
+#define XL_FORM_LR 0x4C000020
+#define XL_FORM_CTR 0x4C000420
+#define XL_FORM_TAR 0x4C000460
+
+#define BO_ALWAYS 0x02800000
+#define BO_CTR 0x02000000
+#define BO_CRBI_OFF 0x00800000
+#define BO_CRBI_ON 0x01800000
+#define BO_CRBI_HINT 0x00400000
+
unsigned int create_branch(const unsigned int *addr,
unsigned long target, int flags);
unsigned int create_cond_branch(const unsigned int *addr,
@@ -56,4 +66,10 @@ static inline unsigned long ppc_function_entry(void *func)
#endif
}
+/* Perf branch filters */
+bool instr_is_return_branch(unsigned int instr);
+bool instr_is_conditional_branch(unsigned int instr);
+bool instr_is_func_call(unsigned int instr);
+bool instr_is_indirect_func_call(unsigned int instr);
+
#endif /* _ASM_POWERPC_CODE_PATCHING_H */
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index d5edbeb..a06f8b3 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -77,6 +77,7 @@ static unsigned int branch_opcode(unsigned int instr)
return (instr >> 26) & 0x3F;
}
+/* Forms of branch instruction */
static int instr_is_branch_iform(unsigned int instr)
{
return branch_opcode(instr) == 18;
@@ -87,6 +88,85 @@ static int instr_is_branch_bform(unsigned int instr)
return branch_opcode(instr) == 16;
}
+static int instr_is_branch_xlform(unsigned int instr)
+{
+ return branch_opcode(instr) == 19;
+}
+
+/* Classification of XL-form instruction */
+static int is_xlform_lr(unsigned int instr)
+{
+ return (instr & XL_FORM_LR) == XL_FORM_LR;
+}
+
+/* BO field analysis (B-form or XL-form) */
+static int is_bo_always(unsigned int instr)
+{
+ return (instr & BO_ALWAYS) == BO_ALWAYS;
+}
+
+/* Link bit is set */
+static int is_branch_link_set(unsigned int instr)
+{
+ return (instr & BRANCH_SET_LINK) == BRANCH_SET_LINK;
+}
+
+/*
+ * Generic software implemented branch filters used
+ * by perf branch stack sampling when PMU does not
+ * process them for some reason.
+ */
+
+/* PERF_SAMPLE_BRANCH_ANY_RETURN */
+bool instr_is_return_branch(unsigned int instr)
+{
+ /*
+ * Conditional and unconditional branch to LR register
+ * without seting the link register.
+ */
+ if (is_xlform_lr(instr) && !is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_COND */
+bool instr_is_conditional_branch(unsigned int instr)
+{
+ /* I-form instruction - excluded */
+ if (instr_is_branch_iform(instr))
+ return false;
+
+ /* B-form or XL-form instruction */
+ if (instr_is_branch_bform(instr) || instr_is_branch_xlform(instr)) {
+
+ /* Not branch always */
+ if (!is_bo_always(instr))
+ return true;
+ }
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_ANY_CALL */
+bool instr_is_func_call(unsigned int instr)
+{
+ /* LR should be set */
+ if (is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
+/* PERF_SAMPLE_BRANCH_IND_CALL */
+bool instr_is_indirect_func_call(unsigned int instr)
+{
+ /* XL-form instruction with LR set */
+ if (instr_is_branch_xlform(instr) && is_branch_link_set(instr))
+ return true;
+
+ return false;
+}
+
int instr_is_relative_branch(unsigned int instr)
{
if (instr & BRANCH_ABSOLUTE)
--
1.7.11.7
--
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