[patch 22/24] Immediate Values - Powerpc Optimization NMI MCE support
Use an atomic update for immediate values.
Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]>
CC: Rusty Russell <[EMAIL PROTECTED]>
CC: Christoph Hellwig <[EMAIL PROTECTED]>
CC: Paul Mackerras <[EMAIL PROTECTED]>
---
arch/powerpc/kernel/Makefile|1
arch/powerpc/kernel/immediate.c | 73
include/asm-powerpc/immediate.h | 18 +
3 files changed, 92 insertions(+)
Index: linux-2.6-lttng/arch/powerpc/kernel/immediate.c
===
--- /dev/null 1970-01-01 00:00:00.0 +
+++ linux-2.6-lttng/arch/powerpc/kernel/immediate.c 2007-12-20
20:52:27.0 -0500
@@ -0,0 +1,73 @@
+/*
+ * Powerpc optimized immediate values enabling/disabling.
+ *
+ * Mathieu Desnoyers <[EMAIL PROTECTED]>
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define LI_OPCODE_LEN 2
+
+/**
+ * arch_imv_update - update one immediate value
+ * @imv: pointer of type const struct __imv to update
+ * @early: early boot (1), normal (0)
+ *
+ * Update one immediate value. Must be called with imv_mutex held.
+ */
+int arch_imv_update(const struct __imv *imv, int early)
+{
+#ifdef CONFIG_KPROBES
+ kprobe_opcode_t *insn;
+ /*
+* Fail if a kprobe has been set on this instruction.
+* (TODO: we could eventually do better and modify all the (possibly
+* nested) kprobes for this site if kprobes had an API for this.
+*/
+ switch (imv->size) {
+ case 1: /* The uint8_t points to the 3rd byte of the
+* instruction */
+ insn = (void *)(imv->imv - 1 - LI_OPCODE_LEN);
+ break;
+ case 2: insn = (void *)(imv->imv - LI_OPCODE_LEN);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (unlikely(!early && *insn == BREAKPOINT_INSTRUCTION)) {
+ printk(KERN_WARNING "Immediate value in conflict with kprobe. "
+ "Variable at %p, "
+ "instruction at %p, size %lu\n",
+ (void *)imv->imv,
+ (void *)imv->var, imv->size);
+ return -EBUSY;
+ }
+#endif
+
+ /*
+* If the variable and the instruction have the same value, there is
+* nothing to do.
+*/
+ switch (imv->size) {
+ case 1: if (*(uint8_t *)imv->imv
+ == *(uint8_t *)imv->var)
+ return 0;
+ break;
+ case 2: if (*(uint16_t *)imv->imv
+ == *(uint16_t *)imv->var)
+ return 0;
+ break;
+ default:return -EINVAL;
+ }
+ memcpy((void *)imv->imv, (void *)imv->var,
+ imv->size);
+ flush_icache_range(imv->imv,
+ imv->imv + imv->size);
+ return 0;
+}
Index: linux-2.6-lttng/include/asm-powerpc/immediate.h
===
--- linux-2.6-lttng.orig/include/asm-powerpc/immediate.h2007-12-20
20:52:20.0 -0500
+++ linux-2.6-lttng/include/asm-powerpc/immediate.h 2007-12-20
20:52:27.0 -0500
@@ -12,6 +12,16 @@
#include
+struct __imv {
+ unsigned long var; /* Identifier variable of the immediate value */
+ unsigned long imv; /*
+* Pointer to the memory location that holds
+* the immediate value within the load immediate
+* instruction.
+*/
+ unsigned char size; /* Type size. */
+} __attribute__ ((packed));
+
/**
* imv_read - read immediate variable
* @name: immediate value name
@@ -19,6 +29,11 @@
* Reads the value of @name.
* Optimized version of the immediate.
* Do not use in __init and __exit functions. Use _imv_read() instead.
+ * Makes sure the 2 bytes update will be atomic by aligning the immediate
+ * value. Use a normal memory read for the 4 bytes immediate because there is
no
+ * way to atomically update it without using a seqlock read side, which would
+ * cost more in term of total i-cache and d-cache space than a simple memory
+ * read.
*/
#define imv_read(name) \
({ \
@@ -40,6 +55,7 @@
PPC_LONG "%c1, ((1f)-2)\n\t"\
".byte 2\n\t" \
".previous\n\t" \
+ ".align 2\n\t" \
"li %0,0\n\t" \
"1:\n\t"\
:
[patch 22/24] Immediate Values - Powerpc Optimization NMI MCE support
Use an atomic update for immediate values.
Signed-off-by: Mathieu Desnoyers [EMAIL PROTECTED]
CC: Rusty Russell [EMAIL PROTECTED]
CC: Christoph Hellwig [EMAIL PROTECTED]
CC: Paul Mackerras [EMAIL PROTECTED]
---
arch/powerpc/kernel/Makefile|1
arch/powerpc/kernel/immediate.c | 73
include/asm-powerpc/immediate.h | 18 +
3 files changed, 92 insertions(+)
Index: linux-2.6-lttng/arch/powerpc/kernel/immediate.c
===
--- /dev/null 1970-01-01 00:00:00.0 +
+++ linux-2.6-lttng/arch/powerpc/kernel/immediate.c 2007-12-20
20:52:27.0 -0500
@@ -0,0 +1,73 @@
+/*
+ * Powerpc optimized immediate values enabling/disabling.
+ *
+ * Mathieu Desnoyers [EMAIL PROTECTED]
+ */
+
+#include linux/module.h
+#include linux/immediate.h
+#include linux/string.h
+#include linux/kprobes.h
+#include asm/cacheflush.h
+#include asm/page.h
+
+#define LI_OPCODE_LEN 2
+
+/**
+ * arch_imv_update - update one immediate value
+ * @imv: pointer of type const struct __imv to update
+ * @early: early boot (1), normal (0)
+ *
+ * Update one immediate value. Must be called with imv_mutex held.
+ */
+int arch_imv_update(const struct __imv *imv, int early)
+{
+#ifdef CONFIG_KPROBES
+ kprobe_opcode_t *insn;
+ /*
+* Fail if a kprobe has been set on this instruction.
+* (TODO: we could eventually do better and modify all the (possibly
+* nested) kprobes for this site if kprobes had an API for this.
+*/
+ switch (imv-size) {
+ case 1: /* The uint8_t points to the 3rd byte of the
+* instruction */
+ insn = (void *)(imv-imv - 1 - LI_OPCODE_LEN);
+ break;
+ case 2: insn = (void *)(imv-imv - LI_OPCODE_LEN);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (unlikely(!early *insn == BREAKPOINT_INSTRUCTION)) {
+ printk(KERN_WARNING Immediate value in conflict with kprobe.
+ Variable at %p,
+ instruction at %p, size %lu\n,
+ (void *)imv-imv,
+ (void *)imv-var, imv-size);
+ return -EBUSY;
+ }
+#endif
+
+ /*
+* If the variable and the instruction have the same value, there is
+* nothing to do.
+*/
+ switch (imv-size) {
+ case 1: if (*(uint8_t *)imv-imv
+ == *(uint8_t *)imv-var)
+ return 0;
+ break;
+ case 2: if (*(uint16_t *)imv-imv
+ == *(uint16_t *)imv-var)
+ return 0;
+ break;
+ default:return -EINVAL;
+ }
+ memcpy((void *)imv-imv, (void *)imv-var,
+ imv-size);
+ flush_icache_range(imv-imv,
+ imv-imv + imv-size);
+ return 0;
+}
Index: linux-2.6-lttng/include/asm-powerpc/immediate.h
===
--- linux-2.6-lttng.orig/include/asm-powerpc/immediate.h2007-12-20
20:52:20.0 -0500
+++ linux-2.6-lttng/include/asm-powerpc/immediate.h 2007-12-20
20:52:27.0 -0500
@@ -12,6 +12,16 @@
#include asm/asm-compat.h
+struct __imv {
+ unsigned long var; /* Identifier variable of the immediate value */
+ unsigned long imv; /*
+* Pointer to the memory location that holds
+* the immediate value within the load immediate
+* instruction.
+*/
+ unsigned char size; /* Type size. */
+} __attribute__ ((packed));
+
/**
* imv_read - read immediate variable
* @name: immediate value name
@@ -19,6 +29,11 @@
* Reads the value of @name.
* Optimized version of the immediate.
* Do not use in __init and __exit functions. Use _imv_read() instead.
+ * Makes sure the 2 bytes update will be atomic by aligning the immediate
+ * value. Use a normal memory read for the 4 bytes immediate because there is
no
+ * way to atomically update it without using a seqlock read side, which would
+ * cost more in term of total i-cache and d-cache space than a simple memory
+ * read.
*/
#define imv_read(name) \
({ \
@@ -40,6 +55,7 @@
PPC_LONG %c1, ((1f)-2)\n\t\
.byte 2\n\t \
.previous\n\t \
+ .align 2\n\t \
li %0,0\n\t \
1:\n\t
