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Merge branch 'arm64/ftrace-with-regs' of git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux into for-next/core 

FTRACE_WITH_REGS support for arm64.

* 'arm64/ftrace-with-regs' of git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux:
  arm64: ftrace: minimize ifdeffery
  arm64: implement ftrace with regs
  arm64: asm-offsets: add S_FP
  arm64: insn: add encoder for MOV (register)
  arm64: module/ftrace: intialize PLT at load time
  arm64: module: rework special section handling
  module/ftrace: handle patchable-function-entry
  ftrace: add ftrace_init_nop()
alistair/sunxi64-5.5-dsi
Catalin Marinas 2019-11-07 11:26:54 +00:00
parent 8301ae822d 7f08ae53a7
commit c1c9ea6371
18 changed files with 362 additions and 90 deletions
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2
arch/arm64/Kconfig
View File

@ -143,6 +143,8 @@ config ARM64
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_REGS \
if $(cc-option,-fpatchable-function-entry=2)
select HAVE_EFFICIENT_UNALIGNED_ACCESS
select HAVE_FAST_GUP
select HAVE_FTRACE_MCOUNT_RECORD

5
arch/arm64/Makefile
View File

@ -95,6 +95,11 @@ ifeq ($(CONFIG_ARM64_MODULE_PLTS),y)
KBUILD_LDS_MODULE += $(srctree)/arch/arm64/kernel/module.lds
endif
ifeq ($(CONFIG_DYNAMIC_FTRACE_WITH_REGS),y)
KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
CC_FLAGS_FTRACE := -fpatchable-function-entry=2
endif
# Default value
head-y := arch/arm64/kernel/head.o

23
arch/arm64/include/asm/ftrace.h
View File

@ -11,9 +11,20 @@
#include <asm/insn.h>
#define HAVE_FUNCTION_GRAPH_FP_TEST
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
#define ARCH_SUPPORTS_FTRACE_OPS 1
#else
#define MCOUNT_ADDR ((unsigned long)_mcount)
#endif
/* The BL at the callsite's adjusted rec->ip */
#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE
#define FTRACE_PLT_IDX 0
#define FTRACE_REGS_PLT_IDX 1
#define NR_FTRACE_PLTS 2
/*
* Currently, gcc tends to save the link register after the local variables
* on the stack. This causes the max stack tracer to report the function
@ -43,6 +54,12 @@ extern void return_to_handler(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
/*
* Adjust addr to point at the BL in the callsite.
* See ftrace_init_nop() for the callsite sequence.
*/
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
return addr + AARCH64_INSN_SIZE;
/*
* addr is the address of the mcount call instruction.
* recordmcount does the necessary offset calculation.
@ -50,6 +67,12 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
return addr;
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
struct dyn_ftrace;
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
#define ftrace_init_nop ftrace_init_nop
#endif
#define ftrace_return_address(n) return_address(n)
/*

3
arch/arm64/include/asm/insn.h
View File

@ -440,6 +440,9 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst,
int shift,
enum aarch64_insn_variant variant,
enum aarch64_insn_logic_type type);
u32 aarch64_insn_gen_move_reg(enum aarch64_insn_register dst,
enum aarch64_insn_register src,
enum aarch64_insn_variant variant);
u32 aarch64_insn_gen_logical_immediate(enum aarch64_insn_logic_type type,
enum aarch64_insn_variant variant,
enum aarch64_insn_register Rn,

2
arch/arm64/include/asm/module.h
View File

@ -21,7 +21,7 @@ struct mod_arch_specific {
struct mod_plt_sec init;
/* for CONFIG_DYNAMIC_FTRACE */
struct plt_entry *ftrace_trampoline;
struct plt_entry *ftrace_trampolines;
};
#endif

1
arch/arm64/kernel/asm-offsets.c
View File

@ -56,6 +56,7 @@ int main(void)
DEFINE(S_X24, offsetof(struct pt_regs, regs[24]));
DEFINE(S_X26, offsetof(struct pt_regs, regs[26]));
DEFINE(S_X28, offsetof(struct pt_regs, regs[28]));
DEFINE(S_FP, offsetof(struct pt_regs, regs[29]));
DEFINE(S_LR, offsetof(struct pt_regs, regs[30]));
DEFINE(S_SP, offsetof(struct pt_regs, sp));
DEFINE(S_PSTATE, offsetof(struct pt_regs, pstate));

140
arch/arm64/kernel/entry-ftrace.S
View File

@ -7,10 +7,137 @@
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
#include <asm/ftrace.h>
#include <asm/insn.h>
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
/*
* Due to -fpatchable-function-entry=2, the compiler has placed two NOPs before
* the regular function prologue. For an enabled callsite, ftrace_init_nop() and
* ftrace_make_call() have patched those NOPs to:
*
* MOV X9, LR
* BL <entry>
*
* ... where <entry> is either ftrace_caller or ftrace_regs_caller.
*
* Each instrumented function follows the AAPCS, so here x0-x8 and x19-x30 are
* live, and x9-x18 are safe to clobber.
*
* We save the callsite's context into a pt_regs before invoking any ftrace
* callbacks. So that we can get a sensible backtrace, we create a stack record
* for the callsite and the ftrace entry assembly. This is not sufficient for
* reliable stacktrace: until we create the callsite stack record, its caller
* is missing from the LR and existing chain of frame records.
*/
.macro ftrace_regs_entry, allregs=0
/* Make room for pt_regs, plus a callee frame */
sub sp, sp, #(S_FRAME_SIZE + 16)
/* Save function arguments (and x9 for simplicity) */
stp x0, x1, [sp, #S_X0]
stp x2, x3, [sp, #S_X2]
stp x4, x5, [sp, #S_X4]
stp x6, x7, [sp, #S_X6]
stp x8, x9, [sp, #S_X8]
/* Optionally save the callee-saved registers, always save the FP */
.if \allregs == 1
stp x10, x11, [sp, #S_X10]
stp x12, x13, [sp, #S_X12]
stp x14, x15, [sp, #S_X14]
stp x16, x17, [sp, #S_X16]
stp x18, x19, [sp, #S_X18]
stp x20, x21, [sp, #S_X20]
stp x22, x23, [sp, #S_X22]
stp x24, x25, [sp, #S_X24]
stp x26, x27, [sp, #S_X26]
stp x28, x29, [sp, #S_X28]
.else
str x29, [sp, #S_FP]
.endif
/* Save the callsite's SP and LR */
add x10, sp, #(S_FRAME_SIZE + 16)
stp x9, x10, [sp, #S_LR]
/* Save the PC after the ftrace callsite */
str x30, [sp, #S_PC]
/* Create a frame record for the callsite above pt_regs */
stp x29, x9, [sp, #S_FRAME_SIZE]
add x29, sp, #S_FRAME_SIZE
/* Create our frame record within pt_regs. */
stp x29, x30, [sp, #S_STACKFRAME]
add x29, sp, #S_STACKFRAME
.endm
ENTRY(ftrace_regs_caller)
ftrace_regs_entry 1
b ftrace_common
ENDPROC(ftrace_regs_caller)
ENTRY(ftrace_caller)
ftrace_regs_entry 0
b ftrace_common
ENDPROC(ftrace_caller)
ENTRY(ftrace_common)
sub x0, x30, #AARCH64_INSN_SIZE // ip (callsite's BL insn)
mov x1, x9 // parent_ip (callsite's LR)
ldr_l x2, function_trace_op // op
mov x3, sp // regs
GLOBAL(ftrace_call)
bl ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
GLOBAL(ftrace_graph_call) // ftrace_graph_caller();
nop // If enabled, this will be replaced
// "b ftrace_graph_caller"
#endif
/*
* At the callsite x0-x8 and x19-x30 were live. Any C code will have preserved
* x19-x29 per the AAPCS, and we created frame records upon entry, so we need
* to restore x0-x8, x29, and x30.
*/
ftrace_common_return:
/* Restore function arguments */
ldp x0, x1, [sp]
ldp x2, x3, [sp, #S_X2]
ldp x4, x5, [sp, #S_X4]
ldp x6, x7, [sp, #S_X6]
ldr x8, [sp, #S_X8]
/* Restore the callsite's FP, LR, PC */
ldr x29, [sp, #S_FP]
ldr x30, [sp, #S_LR]
ldr x9, [sp, #S_PC]
/* Restore the callsite's SP */
add sp, sp, #S_FRAME_SIZE + 16
ret x9
ENDPROC(ftrace_common)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
ldr x0, [sp, #S_PC]
sub x0, x0, #AARCH64_INSN_SIZE // ip (callsite's BL insn)
add x1, sp, #S_LR // parent_ip (callsite's LR)
ldr x2, [sp, #S_FRAME_SIZE] // parent fp (callsite's FP)
bl prepare_ftrace_return
b ftrace_common_return
ENDPROC(ftrace_graph_caller)
#else
#endif
#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
/*
* Gcc with -pg will put the following code in the beginning of each function:
* mov x0, x30
@ -160,11 +287,6 @@ GLOBAL(ftrace_graph_call) // ftrace_graph_caller();
mcount_exit
ENDPROC(ftrace_caller)
#endif /* CONFIG_DYNAMIC_FTRACE */
ENTRY(ftrace_stub)
ret
ENDPROC(ftrace_stub)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
@ -184,7 +306,15 @@ ENTRY(ftrace_graph_caller)
mcount_exit
ENDPROC(ftrace_graph_caller)
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
ENTRY(ftrace_stub)
ret
ENDPROC(ftrace_stub)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
* void return_to_handler(void)
*

123
arch/arm64/kernel/ftrace.c
View File

@ -62,6 +62,19 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
return ftrace_modify_code(pc, 0, new, false);
}
static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
{
#ifdef CONFIG_ARM64_MODULE_PLTS
struct plt_entry *plt = mod->arch.ftrace_trampolines;
if (addr == FTRACE_ADDR)
return &plt[FTRACE_PLT_IDX];
if (addr == FTRACE_REGS_ADDR && IS_ENABLED(CONFIG_FTRACE_WITH_REGS))
return &plt[FTRACE_REGS_PLT_IDX];
#endif
return NULL;
}
/*
* Turn on the call to ftrace_caller() in instrumented function
*/
@ -72,9 +85,11 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
#ifdef CONFIG_ARM64_MODULE_PLTS
struct plt_entry trampoline, *dst;
struct module *mod;
struct plt_entry *plt;
if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
return -EINVAL;
/*
* On kernels that support module PLTs, the offset between the
@ -93,49 +108,13 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
if (WARN_ON(!mod))
return -EINVAL;
/*
* There is only one ftrace trampoline per module. For now,
* this is not a problem since on arm64, all dynamic ftrace
* invocations are routed via ftrace_caller(). This will need
* to be revisited if support for multiple ftrace entry points
* is added in the future, but for now, the pr_err() below
* deals with a theoretical issue only.
*
* Note that PLTs are place relative, and plt_entries_equal()
* checks whether they point to the same target. Here, we need
* to check if the actual opcodes are in fact identical,
* regardless of the offset in memory so use memcmp() instead.
*/
dst = mod->arch.ftrace_trampoline;
trampoline = get_plt_entry(addr, dst);
if (memcmp(dst, &trampoline, sizeof(trampoline))) {
if (plt_entry_is_initialized(dst)) {
pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
return -EINVAL;
}
/* point the trampoline to our ftrace entry point */
module_disable_ro(mod);
*dst = trampoline;
module_enable_ro(mod, true);
/*
* Ensure updated trampoline is visible to instruction
* fetch before we patch in the branch. Although the
* architecture doesn't require an IPI in this case,
* Neoverse-N1 erratum #1542419 does require one
* if the TLB maintenance in module_enable_ro() is
* skipped due to rodata_enabled. It doesn't seem worth
* it to make it conditional given that this is
* certainly not a fast-path.
*/
flush_icache_range((unsigned long)&dst[0],
(unsigned long)&dst[1]);
plt = get_ftrace_plt(mod, addr);
if (!plt) {
pr_err("ftrace: no module PLT for %ps\n", (void *)addr);
return -EINVAL;
}
addr = (unsigned long)dst;
#else /* CONFIG_ARM64_MODULE_PLTS */
return -EINVAL;
#endif /* CONFIG_ARM64_MODULE_PLTS */
addr = (unsigned long)plt;
}
old = aarch64_insn_gen_nop();
@ -144,6 +123,55 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
return ftrace_modify_code(pc, old, new, true);
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
unsigned long pc = rec->ip;
u32 old, new;
old = aarch64_insn_gen_branch_imm(pc, old_addr,
AARCH64_INSN_BRANCH_LINK);
new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
return ftrace_modify_code(pc, old, new, true);
}
/*
* The compiler has inserted two NOPs before the regular function prologue.
* All instrumented functions follow the AAPCS, so x0-x8 and x19-x30 are live,
* and x9-x18 are free for our use.
*
* At runtime we want to be able to swing a single NOP <-> BL to enable or
* disable the ftrace call. The BL requires us to save the original LR value,
* so here we insert a <MOV X9, LR> over the first NOP so the instructions
* before the regular prologue are:
*
* | Compiled | Disabled | Enabled |
* +----------+------------+------------+
* | NOP | MOV X9, LR | MOV X9, LR |
* | NOP | NOP | BL <entry> |
*
* The LR value will be recovered by ftrace_regs_entry, and restored into LR
* before returning to the regular function prologue. When a function is not
* being traced, the MOV is not harmful given x9 is not live per the AAPCS.
*
* Note: ftrace_process_locs() has pre-adjusted rec->ip to be the address of
* the BL.
*/
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
{
unsigned long pc = rec->ip - AARCH64_INSN_SIZE;
u32 old, new;
old = aarch64_insn_gen_nop();
new = aarch64_insn_gen_move_reg(AARCH64_INSN_REG_9,
AARCH64_INSN_REG_LR,
AARCH64_INSN_VARIANT_64BIT);
return ftrace_modify_code(pc, old, new, true);
}
#endif
/*
* Turn off the call to ftrace_caller() in instrumented function
*/
@ -156,9 +184,11 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
#ifdef CONFIG_ARM64_MODULE_PLTS
u32 replaced;
if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
return -EINVAL;
/*
* 'mod' is only set at module load time, but if we end up
* dealing with an out-of-range condition, we can assume it
@ -189,9 +219,6 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
return -EINVAL;
validate = false;
#else /* CONFIG_ARM64_MODULE_PLTS */
return -EINVAL;
#endif /* CONFIG_ARM64_MODULE_PLTS */
} else {
old = aarch64_insn_gen_branch_imm(pc, addr,
AARCH64_INSN_BRANCH_LINK);

13
arch/arm64/kernel/insn.c
View File

@ -1268,6 +1268,19 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst,
return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_6, insn, shift);
}
/*
* MOV (register) is architecturally an alias of ORR (shifted register) where
* MOV <*d>, <*m> is equivalent to ORR <*d>, <*ZR>, <*m>
*/
u32 aarch64_insn_gen_move_reg(enum aarch64_insn_register dst,
enum aarch64_insn_register src,
enum aarch64_insn_variant variant)
{
return aarch64_insn_gen_logical_shifted_reg(dst, AARCH64_INSN_REG_ZR,
src, 0, variant,
AARCH64_INSN_LOGIC_ORR);
}
u32 aarch64_insn_gen_adr(unsigned long pc, unsigned long addr,
enum aarch64_insn_register reg,
enum aarch64_insn_adr_type type)

3
arch/arm64/kernel/module-plts.c
View File

@ -4,6 +4,7 @@
*/
#include <linux/elf.h>
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sort.h>
@ -330,7 +331,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
tramp->sh_type = SHT_NOBITS;
tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
tramp->sh_addralign = __alignof__(struct plt_entry);
tramp->sh_size = sizeof(struct plt_entry);
tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
}
return 0;

57
arch/arm64/kernel/module.c
View File

@ -9,6 +9,7 @@
#include <linux/bitops.h>
#include <linux/elf.h>
#include <linux/ftrace.h>
#include <linux/gfp.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
@ -470,22 +471,58 @@ overflow:
return -ENOEXEC;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
static const Elf_Shdr *find_section(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
const char *name)
{
const Elf_Shdr *s, *se;
const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
if (strcmp(".altinstructions", secstrs + s->sh_name) == 0)
apply_alternatives_module((void *)s->sh_addr, s->sh_size);
#ifdef CONFIG_ARM64_MODULE_PLTS
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) &&
!strcmp(".text.ftrace_trampoline", secstrs + s->sh_name))
me->arch.ftrace_trampoline = (void *)s->sh_addr;
#endif
if (strcmp(name, secstrs + s->sh_name) == 0)
return s;
}
return NULL;
}
static inline void __init_plt(struct plt_entry *plt, unsigned long addr)
{
*plt = get_plt_entry(addr, plt);
}
static int module_init_ftrace_plt(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *mod)
{
#if defined(CONFIG_ARM64_MODULE_PLTS) && defined(CONFIG_DYNAMIC_FTRACE)
const Elf_Shdr *s;
struct plt_entry *plts;
s = find_section(hdr, sechdrs, ".text.ftrace_trampoline");
if (!s)
return -ENOEXEC;
plts = (void *)s->sh_addr;
__init_plt(&plts[FTRACE_PLT_IDX], FTRACE_ADDR);
if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
__init_plt(&plts[FTRACE_REGS_PLT_IDX], FTRACE_REGS_ADDR);
mod->arch.ftrace_trampolines = plts;
#endif
return 0;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
const Elf_Shdr *s;
s = find_section(hdr, sechdrs, ".altinstructions");
if (s)
apply_alternatives_module((void *)s->sh_addr, s->sh_size);
return module_init_ftrace_plt(hdr, sechdrs, me);
}

1
arch/parisc/Makefile
View File

@ -60,7 +60,6 @@ KBUILD_CFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY=1 \
-DFTRACE_PATCHABLE_FUNCTION_SIZE=$(NOP_COUNT)
CC_FLAGS_FTRACE := -fpatchable-function-entry=$(NOP_COUNT),$(shell echo $$(($(NOP_COUNT)-1)))
KBUILD_LDS_MODULE += $(srctree)/arch/parisc/kernel/module.lds
endif
OBJCOPY_FLAGS =-O binary -R .note -R .comment -S

10
arch/parisc/kernel/module.c
View File

@ -43,6 +43,7 @@
#include <linux/elf.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/ftrace.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/bug.h>
@ -862,7 +863,7 @@ int module_finalize(const Elf_Ehdr *hdr,
const char *strtab = NULL;
const Elf_Shdr *s;
char *secstrings;
int err, symindex = -1;
int symindex = -1;
Elf_Sym *newptr, *oldptr;
Elf_Shdr *symhdr = NULL;
#ifdef DEBUG
@ -946,11 +947,13 @@ int module_finalize(const Elf_Ehdr *hdr,
/* patch .altinstructions */
apply_alternatives(aseg, aseg + s->sh_size, me->name);
#ifdef CONFIG_DYNAMIC_FTRACE
/* For 32 bit kernels we're compiling modules with
* -ffunction-sections so we must relocate the addresses in the
*__mcount_loc section.
* ftrace callsite section.
*/
if (symindex != -1 && !strcmp(secname, "__mcount_loc")) {
if (symindex != -1 && !strcmp(secname, FTRACE_CALLSITE_SECTION)) {
int err;
if (s->sh_type == SHT_REL)
err = apply_relocate((Elf_Shdr *)sechdrs,
strtab, symindex,
@ -962,6 +965,7 @@ int module_finalize(const Elf_Ehdr *hdr,
if (err)
return err;
}
#endif
}
return 0;
}

7
arch/parisc/kernel/module.lds
View File

@ -1,7 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
SECTIONS {
__mcount_loc : {
*(__patchable_function_entries)
}
}

14
include/asm-generic/vmlinux.lds.h
View File

@ -110,17 +110,17 @@
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__patchable_function_entries)) \
__stop_mcount_loc = .;
#else
/*
* The ftrace call sites are logged to a section whose name depends on the
* compiler option used. A given kernel image will only use one, AKA
* FTRACE_CALLSITE_SECTION. We capture all of them here to avoid header
* dependencies for FTRACE_CALLSITE_SECTION's definition.
*/
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__mcount_loc)) \
KEEP(*(__patchable_function_entries)) \
__stop_mcount_loc = .;
#endif
#else
#define MCOUNT_REC()
#endif

40
include/linux/ftrace.h
View File

@ -499,7 +499,7 @@ static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
/**
* ftrace_make_nop - convert code into nop
* @mod: module structure if called by module load initialization
* @rec: the mcount call site record
* @rec: the call site record (e.g. mcount/fentry)
* @addr: the address that the call site should be calling
*
* This is a very sensitive operation and great care needs
@ -520,9 +520,38 @@ static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
extern int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr);
/**
* ftrace_init_nop - initialize a nop call site
* @mod: module structure if called by module load initialization
* @rec: the call site record (e.g. mcount/fentry)
*
* This is a very sensitive operation and great care needs
* to be taken by the arch. The operation should carefully
* read the location, check to see if what is read is indeed
* what we expect it to be, and then on success of the compare,
* it should write to the location.
*
* The code segment at @rec->ip should contain the contents created by
* the compiler
*
* Return must be:
* 0 on success
* -EFAULT on error reading the location
* -EINVAL on a failed compare of the contents
* -EPERM on error writing to the location
* Any other value will be considered a failure.
*/
#ifndef ftrace_init_nop
static inline int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
{
return ftrace_make_nop(mod, rec, MCOUNT_ADDR);
}
#endif
/**
* ftrace_make_call - convert a nop call site into a call to addr
* @rec: the mcount call site record
* @rec: the call site record (e.g. mcount/fentry)
* @addr: the address that the call site should call
*
* This is a very sensitive operation and great care needs
@ -545,7 +574,7 @@ extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
/**
* ftrace_modify_call - convert from one addr to another (no nop)
* @rec: the mcount call site record
* @rec: the call site record (e.g. mcount/fentry)
* @old_addr: the address expected to be currently called to
* @addr: the address to change to
*
@ -709,6 +738,11 @@ static inline unsigned long get_lock_parent_ip(void)
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
extern void ftrace_init(void);
#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
#define FTRACE_CALLSITE_SECTION "__patchable_function_entries"
#else
#define FTRACE_CALLSITE_SECTION "__mcount_loc"
#endif
#else
static inline void ftrace_init(void) { }
#endif

2
kernel/module.c
View File

@ -3222,7 +3222,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
/* sechdrs[0].sh_size is always zero */
mod->ftrace_callsites = section_objs(info, "__mcount_loc",
mod->ftrace_callsites = section_objs(info, FTRACE_CALLSITE_SECTION,
sizeof(*mod->ftrace_callsites),
&mod->num_ftrace_callsites);
#endif

6
kernel/trace/ftrace.c
View File

@ -2494,14 +2494,14 @@ struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter)
}
static int
ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
ftrace_nop_initialize(struct module *mod, struct dyn_ftrace *rec)
{
int ret;
if (unlikely(ftrace_disabled))
return 0;
ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
ret = ftrace_init_nop(mod, rec);
if (ret) {
ftrace_bug_type = FTRACE_BUG_INIT;
ftrace_bug(ret, rec);
@ -2943,7 +2943,7 @@ static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs)
* to the NOP instructions.
*/
if (!__is_defined(CC_USING_NOP_MCOUNT) &&
!ftrace_code_disable(mod, p))
!ftrace_nop_initialize(mod, p))
break;
update_cnt++;