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Subject[PATCH 09/10] ARM: ftrace: add Thumb-2 support to dynamic ftrace
Date
Handle the different nop and call instructions for Thumb-2.  Also, we
need to adjust the recorded mcount_loc addresses because they have the
lsb set.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Rabin Vincent <rabin@rab.in>
---
arch/arm/include/asm/ftrace.h | 4 ++++
arch/arm/kernel/ftrace.c | 33 +++++++++++++++++++++++++++++++++
scripts/recordmcount.pl | 2 +-
3 files changed, 38 insertions(+), 1 deletions(-)
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 4a56a2e..0845f2d 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -18,7 +18,11 @@ struct dyn_arch_ftrace {

static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
+#ifdef CONFIG_THUMB2_KERNEL
+ return addr & ~1;
+#else
return addr;
+#endif
}

extern void ftrace_caller_old(void);
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index f09014c..971ac8c 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -18,7 +18,11 @@
#include <asm/cacheflush.h>
#include <asm/ftrace.h>

+#ifdef CONFIG_THUMB2_KERNEL
+#define NOP 0xeb04f85d /* pop.w {lr} */
+#else
#define NOP 0xe8bd4000 /* pop {lr} */
+#endif

#ifdef CONFIG_OLD_MCOUNT
#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
@@ -56,6 +60,34 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
#endif

/* construct a branch (BL) instruction to addr */
+#ifdef CONFIG_THUMB2_KERNEL
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+ unsigned long s, j1, j2, i1, i2, imm10, imm11;
+ unsigned long first, second;
+ long offset;
+
+ offset = (long)addr - (long)(pc + 4);
+ if (offset < -16777216 || offset > 16777214) {
+ WARN_ON_ONCE(1);
+ return 0;
+ }
+
+ s = (offset >> 24) & 0x1;
+ i1 = (offset >> 23) & 0x1;
+ i2 = (offset >> 22) & 0x1;
+ imm10 = (offset >> 12) & 0x3ff;
+ imm11 = (offset >> 1) & 0x7ff;
+
+ j1 = (!i1) ^ s;
+ j2 = (!i2) ^ s;
+
+ first = 0xf000 | (s << 10) | imm10;
+ second = 0xd000 | (j1 << 13) | (j2 << 11) | imm11;
+
+ return (second << 16) | first;
+}
+#else
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
long offset;
@@ -73,6 +105,7 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)

return 0xeb000000 | offset;
}
+#endif

static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 66c1c4b..88b083b 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -267,7 +267,7 @@ if ($arch eq "x86_64") {
} elsif ($arch eq "arm") {
$alignment = 2;
$section_type = '%progbits';
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24)" .
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_ARM_(CALL|PC24|THM_CALL)" .
"\\s+(__gnu_mcount_nc|mcount)\$";

} elsif ($arch eq "ia64") {
--
1.6.6


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