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-rw-r--r--arch/x86/kernel/cpu/perfctr-watchdog.c11
-rw-r--r--arch/x86/kernel/entry_32.S14
-rw-r--r--arch/x86/kernel/entry_64.S26
-rw-r--r--arch/x86/kernel/ftrace.c124
4 files changed, 86 insertions, 89 deletions
diff --git a/arch/x86/kernel/cpu/perfctr-watchdog.c b/arch/x86/kernel/cpu/perfctr-watchdog.c
index 6bff382094f5..9abd48b22674 100644
--- a/arch/x86/kernel/cpu/perfctr-watchdog.c
+++ b/arch/x86/kernel/cpu/perfctr-watchdog.c
@@ -17,6 +17,8 @@
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/nmi.h>
+#include <linux/kprobes.h>
+
#include <asm/apic.h>
#include <asm/intel_arch_perfmon.h>
@@ -336,7 +338,8 @@ static void single_msr_unreserve(void)
release_perfctr_nmi(wd_ops->perfctr);
}
-static void single_msr_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes
+single_msr_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
/* start the cycle over again */
write_watchdog_counter(wd->perfctr_msr, NULL, nmi_hz);
@@ -401,7 +404,7 @@ static int setup_p6_watchdog(unsigned nmi_hz)
return 1;
}
-static void p6_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes p6_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
/*
* P6 based Pentium M need to re-unmask
@@ -605,7 +608,7 @@ static void p4_unreserve(void)
release_perfctr_nmi(MSR_P4_IQ_PERFCTR0);
}
-static void p4_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
+static void __kprobes p4_rearm(struct nmi_watchdog_ctlblk *wd, unsigned nmi_hz)
{
unsigned dummy;
/*
@@ -784,7 +787,7 @@ unsigned lapic_adjust_nmi_hz(unsigned hz)
return hz;
}
-int lapic_wd_event(unsigned nmi_hz)
+int __kprobes lapic_wd_event(unsigned nmi_hz)
{
struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);
u64 ctr;
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 4d82171d0f9c..c356423a6026 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1153,20 +1153,6 @@ ENDPROC(xen_failsafe_callback)
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
- pushl %eax
- pushl %ecx
- pushl %edx
- movl 0xc(%esp), %eax
- subl $MCOUNT_INSN_SIZE, %eax
-
-.globl mcount_call
-mcount_call:
- call ftrace_stub
-
- popl %edx
- popl %ecx
- popl %eax
-
ret
END(mcount)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1db6ce4314e1..09e7145484c5 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -64,32 +64,6 @@
#ifdef CONFIG_FTRACE
#ifdef CONFIG_DYNAMIC_FTRACE
ENTRY(mcount)
-
- subq $0x38, %rsp
- movq %rax, (%rsp)
- movq %rcx, 8(%rsp)
- movq %rdx, 16(%rsp)
- movq %rsi, 24(%rsp)
- movq %rdi, 32(%rsp)
- movq %r8, 40(%rsp)
- movq %r9, 48(%rsp)
-
- movq 0x38(%rsp), %rdi
- subq $MCOUNT_INSN_SIZE, %rdi
-
-.globl mcount_call
-mcount_call:
- call ftrace_stub
-
- movq 48(%rsp), %r9
- movq 40(%rsp), %r8
- movq 32(%rsp), %rdi
- movq 24(%rsp), %rsi
- movq 16(%rsp), %rdx
- movq 8(%rsp), %rcx
- movq (%rsp), %rax
- addq $0x38, %rsp
-
retq
END(mcount)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ab115cd15fdf..d073d981a730 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -11,17 +11,18 @@
#include <linux/spinlock.h>
#include <linux/hardirq.h>
+#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/list.h>
-#include <asm/alternative.h>
#include <asm/ftrace.h>
+#include <asm/nops.h>
/* Long is fine, even if it is only 4 bytes ;-) */
-static long *ftrace_nop;
+static unsigned long *ftrace_nop;
union ftrace_code_union {
char code[MCOUNT_INSN_SIZE];
@@ -60,11 +61,7 @@ notrace int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code)
{
- unsigned replaced;
- unsigned old = *(unsigned *)old_code; /* 4 bytes */
- unsigned new = *(unsigned *)new_code; /* 4 bytes */
- unsigned char newch = new_code[4];
- int faulted = 0;
+ unsigned char replaced[MCOUNT_INSN_SIZE];
/*
* Note: Due to modules and __init, code can
@@ -72,29 +69,20 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
* as well as code changing.
*
* No real locking needed, this code is run through
- * kstop_machine.
+ * kstop_machine, or before SMP starts.
*/
- asm volatile (
- "1: lock\n"
- " cmpxchg %3, (%2)\n"
- " jnz 2f\n"
- " movb %b4, 4(%2)\n"
- "2:\n"
- ".section .fixup, \"ax\"\n"
- "3: movl $1, %0\n"
- " jmp 2b\n"
- ".previous\n"
- _ASM_EXTABLE(1b, 3b)
- : "=r"(faulted), "=a"(replaced)
- : "r"(ip), "r"(new), "c"(newch),
- "0"(faulted), "a"(old)
- : "memory");
- sync_core();
+ if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE))
+ return 1;
+
+ if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+ return 2;
- if (replaced != old && replaced != new)
- faulted = 2;
+ WARN_ON_ONCE(__copy_to_user_inatomic((char __user *)ip, new_code,
+ MCOUNT_INSN_SIZE));
- return faulted;
+ sync_core();
+
+ return 0;
}
notrace int ftrace_update_ftrace_func(ftrace_func_t func)
@@ -112,30 +100,76 @@ notrace int ftrace_update_ftrace_func(ftrace_func_t func)
notrace int ftrace_mcount_set(unsigned long *data)
{
- unsigned long ip = (long)(&mcount_call);
- unsigned long *addr = data;
- unsigned char old[MCOUNT_INSN_SIZE], *new;
-
- /*
- * Replace the mcount stub with a pointer to the
- * ip recorder function.
- */
- memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
- new = ftrace_call_replace(ip, *addr);
- *addr = ftrace_modify_code(ip, old, new);
-
+ /* mcount is initialized as a nop */
+ *data = 0;
return 0;
}
int __init ftrace_dyn_arch_init(void *data)
{
- const unsigned char *const *noptable = find_nop_table();
-
- /* This is running in kstop_machine */
-
- ftrace_mcount_set(data);
+ extern const unsigned char ftrace_test_p6nop[];
+ extern const unsigned char ftrace_test_nop5[];
+ extern const unsigned char ftrace_test_jmp[];
+ int faulted = 0;
- ftrace_nop = (unsigned long *)noptable[MCOUNT_INSN_SIZE];
+ /*
+ * There is no good nop for all x86 archs.
+ * We will default to using the P6_NOP5, but first we
+ * will test to make sure that the nop will actually
+ * work on this CPU. If it faults, we will then
+ * go to a lesser efficient 5 byte nop. If that fails
+ * we then just use a jmp as our nop. This isn't the most
+ * efficient nop, but we can not use a multi part nop
+ * since we would then risk being preempted in the middle
+ * of that nop, and if we enabled tracing then, it might
+ * cause a system crash.
+ *
+ * TODO: check the cpuid to determine the best nop.
+ */
+ asm volatile (
+ "jmp ftrace_test_jmp\n"
+ /* This code needs to stay around */
+ ".section .text, \"ax\"\n"
+ "ftrace_test_jmp:"
+ "jmp ftrace_test_p6nop\n"
+ "nop\n"
+ "nop\n"
+ "nop\n" /* 2 byte jmp + 3 bytes */
+ "ftrace_test_p6nop:"
+ P6_NOP5
+ "jmp 1f\n"
+ "ftrace_test_nop5:"
+ ".byte 0x66,0x66,0x66,0x66,0x90\n"
+ "jmp 1f\n"
+ ".previous\n"
+ "1:"
+ ".section .fixup, \"ax\"\n"
+ "2: movl $1, %0\n"
+ " jmp ftrace_test_nop5\n"
+ "3: movl $2, %0\n"
+ " jmp 1b\n"
+ ".previous\n"
+ _ASM_EXTABLE(ftrace_test_p6nop, 2b)
+ _ASM_EXTABLE(ftrace_test_nop5, 3b)
+ : "=r"(faulted) : "0" (faulted));
+
+ switch (faulted) {
+ case 0:
+ pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
+ ftrace_nop = (unsigned long *)ftrace_test_p6nop;
+ break;
+ case 1:
+ pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
+ ftrace_nop = (unsigned long *)ftrace_test_nop5;
+ break;
+ case 2:
+ pr_info("ftrace: converting mcount calls to jmp . + 5\n");
+ ftrace_nop = (unsigned long *)ftrace_test_jmp;
+ break;
+ }
+
+ /* The return code is retured via data */
+ *(unsigned long *)data = 0;
return 0;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-03 00:55:10 +0000