summaryrefslogtreecommitdiffstats
path: root/arch/mips/kernel/ftrace.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/mips/kernel/ftrace.c')
-rw-r--r--arch/mips/kernel/ftrace.c179
1 files changed, 95 insertions, 84 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index 5a84a1f11231..94ca2b018af7 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -17,29 +17,13 @@
#include <asm/cacheflush.h>
#include <asm/uasm.h>
-/*
- * If the Instruction Pointer is in module space (0xc0000000), return true;
- * otherwise, it is in kernel space (0x80000000), return false.
- *
- * FIXME: This will not work when the kernel space and module space are the
- * same. If they are the same, we need to modify scripts/recordmcount.pl,
- * ftrace_make_nop/call() and the other related parts to ensure the
- * enabling/disabling of the calling site to _mcount is right for both kernel
- * and module.
- */
-
-static inline int in_module(unsigned long ip)
-{
- return ip & 0x40000000;
-}
+#include <asm-generic/sections.h>
#ifdef CONFIG_DYNAMIC_FTRACE
#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
-#define INSN_B_1F_4 0x10000004 /* b 1f; offset = 4 */
-#define INSN_B_1F_5 0x10000005 /* b 1f; offset = 5 */
#define INSN_NOP 0x00000000 /* nop */
#define INSN_JAL(addr) \
((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
@@ -69,6 +53,20 @@ static inline void ftrace_dyn_arch_init_insns(void)
#endif
}
+/*
+ * Check if the address is in kernel space
+ *
+ * Clone core_kernel_text() from kernel/extable.c, but doesn't call
+ * init_kernel_text() for Ftrace doesn't trace functions in init sections.
+ */
+static inline int in_kernel_space(unsigned long ip)
+{
+ if (ip >= (unsigned long)_stext &&
+ ip <= (unsigned long)_etext)
+ return 1;
+ return 0;
+}
+
static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
{
int faulted;
@@ -84,6 +82,42 @@ static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
return 0;
}
+/*
+ * The details about the calling site of mcount on MIPS
+ *
+ * 1. For kernel:
+ *
+ * move at, ra
+ * jal _mcount --> nop
+ *
+ * 2. For modules:
+ *
+ * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
+ *
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
+ * addiu v1, v1, low_16bit_of_mcount
+ * move at, ra
+ * move $12, ra_address
+ * jalr v1
+ * sub sp, sp, 8
+ * 1: offset = 5 instructions
+ * 2.2 For the Other situations
+ *
+ * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
+ * addiu v1, v1, low_16bit_of_mcount
+ * move at, ra
+ * jalr v1
+ * nop | move $12, ra_address | sub sp, sp, 8
+ * 1: offset = 4 instructions
+ */
+
+#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
+#define MCOUNT_OFFSET_INSNS 5
+#else
+#define MCOUNT_OFFSET_INSNS 4
+#endif
+#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
+
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
@@ -91,39 +125,11 @@ int ftrace_make_nop(struct module *mod,
unsigned long ip = rec->ip;
/*
- * We have compiled module with -mlong-calls, but compiled the kernel
- * without it, we need to cope with them respectively.
+ * If ip is in kernel space, no long call, otherwise, long call is
+ * needed.
*/
- if (in_module(ip)) {
-#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
- /*
- * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
- * addiu v1, v1, low_16bit_of_mcount
- * move at, ra
- * move $12, ra_address
- * jalr v1
- * sub sp, sp, 8
- * 1: offset = 5 instructions
- */
- new = INSN_B_1F_5;
-#else
- /*
- * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
- * addiu v1, v1, low_16bit_of_mcount
- * move at, ra
- * jalr v1
- * nop | move $12, ra_address | sub sp, sp, 8
- * 1: offset = 4 instructions
- */
- new = INSN_B_1F_4;
-#endif
- } else {
- /*
- * move at, ra
- * jal _mcount --> nop
- */
- new = INSN_NOP;
- }
+ new = in_kernel_space(ip) ? INSN_NOP : INSN_B_1F;
+
return ftrace_modify_code(ip, new);
}
@@ -132,8 +138,8 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
unsigned int new;
unsigned long ip = rec->ip;
- /* ip, module: 0xc0000000, kernel: 0x80000000 */
- new = in_module(ip) ? insn_lui_v1_hi16_mcount : insn_jal_ftrace_caller;
+ new = in_kernel_space(ip) ? insn_jal_ftrace_caller :
+ insn_lui_v1_hi16_mcount;
return ftrace_modify_code(ip, new);
}
@@ -190,29 +196,25 @@ int ftrace_disable_ftrace_graph_caller(void)
#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
-unsigned long ftrace_get_parent_addr(unsigned long self_addr,
- unsigned long parent,
- unsigned long parent_addr,
- unsigned long fp)
+unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
+ old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
{
- unsigned long sp, ip, ra;
+ unsigned long sp, ip, tmp;
unsigned int code;
int faulted;
/*
- * For module, move the ip from calling site of mcount to the
- * instruction "lui v1, hi_16bit_of_mcount"(offset is 20), but for
- * kernel, move to the instruction "move ra, at"(offset is 12)
+ * For module, move the ip from the return address after the
+ * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
+ * kernel, move after the instruction "move ra, at"(offset is 16)
*/
- ip = self_addr - (in_module(self_addr) ? 20 : 12);
+ ip = self_ra - (in_kernel_space(self_ra) ? 16 : 24);
/*
* search the text until finding the non-store instruction or "s{d,w}
* ra, offset(sp)" instruction
*/
do {
- ip -= 4;
-
/* get the code at "ip": code = *(unsigned int *)ip; */
safe_load_code(code, ip, faulted);
@@ -224,18 +226,20 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
* store the ra on the stack
*/
if ((code & S_R_SP) != S_R_SP)
- return parent_addr;
+ return parent_ra_addr;
- } while (((code & S_RA_SP) != S_RA_SP));
+ /* Move to the next instruction */
+ ip -= 4;
+ } while ((code & S_RA_SP) != S_RA_SP);
sp = fp + (code & OFFSET_MASK);
- /* ra = *(unsigned long *)sp; */
- safe_load_stack(ra, sp, faulted);
+ /* tmp = *(unsigned long *)sp; */
+ safe_load_stack(tmp, sp, faulted);
if (unlikely(faulted))
return 0;
- if (ra == parent)
+ if (tmp == old_parent_ra)
return sp;
return 0;
}
@@ -246,21 +250,21 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr,
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
-void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
unsigned long fp)
{
- unsigned long old;
+ unsigned long old_parent_ra;
struct ftrace_graph_ent trace;
unsigned long return_hooker = (unsigned long)
&return_to_handler;
- int faulted;
+ int faulted, insns;
if (unlikely(atomic_read(&current->tracing_graph_pause)))
return;
/*
- * "parent" is the stack address saved the return address of the caller
- * of _mcount.
+ * "parent_ra_addr" is the stack address saved the return address of
+ * the caller of _mcount.
*
* if the gcc < 4.5, a leaf function does not save the return address
* in the stack address, so, we "emulate" one in _mcount's stack space,
@@ -275,37 +279,44 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
* do it in ftrace_graph_caller of mcount.S.
*/
- /* old = *parent; */
- safe_load_stack(old, parent, faulted);
+ /* old_parent_ra = *parent_ra_addr; */
+ safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
if (unlikely(faulted))
goto out;
#ifndef KBUILD_MCOUNT_RA_ADDRESS
- parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,
- (unsigned long)parent, fp);
+ parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
+ old_parent_ra, (unsigned long)parent_ra_addr, fp);
/*
* If fails when getting the stack address of the non-leaf function's
* ra, stop function graph tracer and return
*/
- if (parent == 0)
+ if (parent_ra_addr == 0)
goto out;
#endif
- /* *parent = return_hooker; */
- safe_store_stack(return_hooker, parent, faulted);
+ /* *parent_ra_addr = return_hooker; */
+ safe_store_stack(return_hooker, parent_ra_addr, faulted);
if (unlikely(faulted))
goto out;
- if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) ==
- -EBUSY) {
- *parent = old;
+ if (ftrace_push_return_trace(old_parent_ra, self_ra, &trace.depth, fp)
+ == -EBUSY) {
+ *parent_ra_addr = old_parent_ra;
return;
}
- trace.func = self_addr;
+ /*
+ * Get the recorded ip of the current mcount calling site in the
+ * __mcount_loc section, which will be used to filter the function
+ * entries configured through the tracing/set_graph_function interface.
+ */
+
+ insns = in_kernel_space(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
+ trace.func = self_ra - (MCOUNT_INSN_SIZE * insns);
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;
- *parent = old;
+ *parent_ra_addr = old_parent_ra;
}
return;
out:
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-23 11:46:25 +0100