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-rw-r--r--arch/Kconfig13
-rw-r--r--arch/x86/Kconfig4
-rw-r--r--arch/x86/events/core.c134
-rw-r--r--arch/x86/include/asm/static_call.h40
-rw-r--r--arch/x86/include/asm/text-patching.h19
-rw-r--r--arch/x86/kernel/Makefile1
-rw-r--r--arch/x86/kernel/alternative.c5
-rw-r--r--arch/x86/kernel/kprobes/opt.c4
-rw-r--r--arch/x86/kernel/setup.c2
-rw-r--r--arch/x86/kernel/static_call.c98
-rw-r--r--arch/x86/kernel/vmlinux.lds.S1
11 files changed, 279 insertions, 42 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index af14a567b493..76ec3395b843 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -106,6 +106,12 @@ config STATIC_KEYS_SELFTEST
help
Boot time self-test of the branch patching code.
+config STATIC_CALL_SELFTEST
+ bool "Static call selftest"
+ depends on HAVE_STATIC_CALL
+ help
+ Boot time self-test of the call patching code.
+
config OPTPROBES
def_bool y
depends on KPROBES && HAVE_OPTPROBES
@@ -975,6 +981,13 @@ config HAVE_SPARSE_SYSCALL_NR
config ARCH_HAS_VDSO_DATA
bool
+config HAVE_STATIC_CALL
+ bool
+
+config HAVE_STATIC_CALL_INLINE
+ bool
+ depends on HAVE_STATIC_CALL
+
source "kernel/gcov/Kconfig"
source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e876b3a087f9..835d93006bd6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -215,6 +215,8 @@ config X86
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
select HAVE_STACK_VALIDATION if X86_64
+ select HAVE_STATIC_CALL
+ select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UNSTABLE_SCHED_CLOCK
@@ -230,6 +232,7 @@ config X86
select RTC_MC146818_LIB
select SPARSE_IRQ
select SRCU
+ select STACK_VALIDATION if HAVE_STACK_VALIDATION && (HAVE_STATIC_CALL_INLINE || RETPOLINE)
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select USER_STACKTRACE_SUPPORT
@@ -451,7 +454,6 @@ config GOLDFISH
config RETPOLINE
bool "Avoid speculative indirect branches in kernel"
default y
- select STACK_VALIDATION if HAVE_STACK_VALIDATION
help
Compile kernel with the retpoline compiler options to guard against
kernel-to-user data leaks by avoiding speculative indirect
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 1cbf57dc2ac8..360c395d51d0 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -28,6 +28,7 @@
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/nospec.h>
+#include <linux/static_call.h>
#include <asm/apic.h>
#include <asm/stacktrace.h>
@@ -52,6 +53,34 @@ DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
DEFINE_STATIC_KEY_FALSE(rdpmc_never_available_key);
DEFINE_STATIC_KEY_FALSE(rdpmc_always_available_key);
+/*
+ * This here uses DEFINE_STATIC_CALL_NULL() to get a static_call defined
+ * from just a typename, as opposed to an actual function.
+ */
+DEFINE_STATIC_CALL_NULL(x86_pmu_handle_irq, *x86_pmu.handle_irq);
+DEFINE_STATIC_CALL_NULL(x86_pmu_disable_all, *x86_pmu.disable_all);
+DEFINE_STATIC_CALL_NULL(x86_pmu_enable_all, *x86_pmu.enable_all);
+DEFINE_STATIC_CALL_NULL(x86_pmu_enable, *x86_pmu.enable);
+DEFINE_STATIC_CALL_NULL(x86_pmu_disable, *x86_pmu.disable);
+
+DEFINE_STATIC_CALL_NULL(x86_pmu_add, *x86_pmu.add);
+DEFINE_STATIC_CALL_NULL(x86_pmu_del, *x86_pmu.del);
+DEFINE_STATIC_CALL_NULL(x86_pmu_read, *x86_pmu.read);
+
+DEFINE_STATIC_CALL_NULL(x86_pmu_schedule_events, *x86_pmu.schedule_events);
+DEFINE_STATIC_CALL_NULL(x86_pmu_get_event_constraints, *x86_pmu.get_event_constraints);
+DEFINE_STATIC_CALL_NULL(x86_pmu_put_event_constraints, *x86_pmu.put_event_constraints);
+
+DEFINE_STATIC_CALL_NULL(x86_pmu_start_scheduling, *x86_pmu.start_scheduling);
+DEFINE_STATIC_CALL_NULL(x86_pmu_commit_scheduling, *x86_pmu.commit_scheduling);
+DEFINE_STATIC_CALL_NULL(x86_pmu_stop_scheduling, *x86_pmu.stop_scheduling);
+
+DEFINE_STATIC_CALL_NULL(x86_pmu_sched_task, *x86_pmu.sched_task);
+DEFINE_STATIC_CALL_NULL(x86_pmu_swap_task_ctx, *x86_pmu.swap_task_ctx);
+
+DEFINE_STATIC_CALL_NULL(x86_pmu_drain_pebs, *x86_pmu.drain_pebs);
+DEFINE_STATIC_CALL_NULL(x86_pmu_pebs_aliases, *x86_pmu.pebs_aliases);
+
u64 __read_mostly hw_cache_event_ids
[PERF_COUNT_HW_CACHE_MAX]
[PERF_COUNT_HW_CACHE_OP_MAX]
@@ -660,7 +689,7 @@ static void x86_pmu_disable(struct pmu *pmu)
cpuc->enabled = 0;
barrier();
- x86_pmu.disable_all();
+ static_call(x86_pmu_disable_all)();
}
void x86_pmu_enable_all(int added)
@@ -907,8 +936,7 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
n0 -= cpuc->n_txn;
- if (x86_pmu.start_scheduling)
- x86_pmu.start_scheduling(cpuc);
+ static_call_cond(x86_pmu_start_scheduling)(cpuc);
for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
c = cpuc->event_constraint[i];
@@ -925,7 +953,7 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
* change due to external factors (sibling state, allow_tfa).
*/
if (!c || (c->flags & PERF_X86_EVENT_DYNAMIC)) {
- c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]);
+ c = static_call(x86_pmu_get_event_constraints)(cpuc, i, cpuc->event_list[i]);
cpuc->event_constraint[i] = c;
}
@@ -1008,8 +1036,7 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
if (!unsched && assign) {
for (i = 0; i < n; i++) {
e = cpuc->event_list[i];
- if (x86_pmu.commit_scheduling)
- x86_pmu.commit_scheduling(cpuc, i, assign[i]);
+ static_call_cond(x86_pmu_commit_scheduling)(cpuc, i, assign[i]);
}
} else {
for (i = n0; i < n; i++) {
@@ -1018,15 +1045,13 @@ int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
/*
* release events that failed scheduling
*/
- if (x86_pmu.put_event_constraints)
- x86_pmu.put_event_constraints(cpuc, e);
+ static_call_cond(x86_pmu_put_event_constraints)(cpuc, e);
cpuc->event_constraint[i] = NULL;
}
}
- if (x86_pmu.stop_scheduling)
- x86_pmu.stop_scheduling(cpuc);
+ static_call_cond(x86_pmu_stop_scheduling)(cpuc);
return unsched ? -EINVAL : 0;
}
@@ -1226,7 +1251,7 @@ static void x86_pmu_enable(struct pmu *pmu)
cpuc->enabled = 1;
barrier();
- x86_pmu.enable_all(added);
+ static_call(x86_pmu_enable_all)(added);
}
static DEFINE_PER_CPU(u64 [X86_PMC_IDX_MAX], pmc_prev_left);
@@ -1347,7 +1372,7 @@ static int x86_pmu_add(struct perf_event *event, int flags)
if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
goto done_collect;
- ret = x86_pmu.schedule_events(cpuc, n, assign);
+ ret = static_call(x86_pmu_schedule_events)(cpuc, n, assign);
if (ret)
goto out;
/*
@@ -1365,13 +1390,11 @@ done_collect:
cpuc->n_added += n - n0;
cpuc->n_txn += n - n0;
- if (x86_pmu.add) {
- /*
- * This is before x86_pmu_enable() will call x86_pmu_start(),
- * so we enable LBRs before an event needs them etc..
- */
- x86_pmu.add(event);
- }
+ /*
+ * This is before x86_pmu_enable() will call x86_pmu_start(),
+ * so we enable LBRs before an event needs them etc..
+ */
+ static_call_cond(x86_pmu_add)(event);
ret = 0;
out:
@@ -1399,7 +1422,7 @@ static void x86_pmu_start(struct perf_event *event, int flags)
cpuc->events[idx] = event;
__set_bit(idx, cpuc->active_mask);
__set_bit(idx, cpuc->running);
- x86_pmu.enable(event);
+ static_call(x86_pmu_enable)(event);
perf_event_update_userpage(event);
}
@@ -1469,7 +1492,7 @@ void x86_pmu_stop(struct perf_event *event, int flags)
struct hw_perf_event *hwc = &event->hw;
if (test_bit(hwc->idx, cpuc->active_mask)) {
- x86_pmu.disable(event);
+ static_call(x86_pmu_disable)(event);
__clear_bit(hwc->idx, cpuc->active_mask);
cpuc->events[hwc->idx] = NULL;
WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
@@ -1519,8 +1542,7 @@ static void x86_pmu_del(struct perf_event *event, int flags)
if (i >= cpuc->n_events - cpuc->n_added)
--cpuc->n_added;
- if (x86_pmu.put_event_constraints)
- x86_pmu.put_event_constraints(cpuc, event);
+ static_call_cond(x86_pmu_put_event_constraints)(cpuc, event);
/* Delete the array entry. */
while (++i < cpuc->n_events) {
@@ -1533,13 +1555,12 @@ static void x86_pmu_del(struct perf_event *event, int flags)
perf_event_update_userpage(event);
do_del:
- if (x86_pmu.del) {
- /*
- * This is after x86_pmu_stop(); so we disable LBRs after any
- * event can need them etc..
- */
- x86_pmu.del(event);
- }
+
+ /*
+ * This is after x86_pmu_stop(); so we disable LBRs after any
+ * event can need them etc..
+ */
+ static_call_cond(x86_pmu_del)(event);
}
int x86_pmu_handle_irq(struct pt_regs *regs)
@@ -1617,7 +1638,7 @@ perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs)
return NMI_DONE;
start_clock = sched_clock();
- ret = x86_pmu.handle_irq(regs);
+ ret = static_call(x86_pmu_handle_irq)(regs);
finish_clock = sched_clock();
perf_sample_event_took(finish_clock - start_clock);
@@ -1830,6 +1851,38 @@ ssize_t x86_event_sysfs_show(char *page, u64 config, u64 event)
static struct attribute_group x86_pmu_attr_group;
static struct attribute_group x86_pmu_caps_group;
+static void x86_pmu_static_call_update(void)
+{
+ static_call_update(x86_pmu_handle_irq, x86_pmu.handle_irq);
+ static_call_update(x86_pmu_disable_all, x86_pmu.disable_all);
+ static_call_update(x86_pmu_enable_all, x86_pmu.enable_all);
+ static_call_update(x86_pmu_enable, x86_pmu.enable);
+ static_call_update(x86_pmu_disable, x86_pmu.disable);
+
+ static_call_update(x86_pmu_add, x86_pmu.add);
+ static_call_update(x86_pmu_del, x86_pmu.del);
+ static_call_update(x86_pmu_read, x86_pmu.read);
+
+ static_call_update(x86_pmu_schedule_events, x86_pmu.schedule_events);
+ static_call_update(x86_pmu_get_event_constraints, x86_pmu.get_event_constraints);
+ static_call_update(x86_pmu_put_event_constraints, x86_pmu.put_event_constraints);
+
+ static_call_update(x86_pmu_start_scheduling, x86_pmu.start_scheduling);
+ static_call_update(x86_pmu_commit_scheduling, x86_pmu.commit_scheduling);
+ static_call_update(x86_pmu_stop_scheduling, x86_pmu.stop_scheduling);
+
+ static_call_update(x86_pmu_sched_task, x86_pmu.sched_task);
+ static_call_update(x86_pmu_swap_task_ctx, x86_pmu.swap_task_ctx);
+
+ static_call_update(x86_pmu_drain_pebs, x86_pmu.drain_pebs);
+ static_call_update(x86_pmu_pebs_aliases, x86_pmu.pebs_aliases);
+}
+
+static void _x86_pmu_read(struct perf_event *event)
+{
+ x86_perf_event_update(event);
+}
+
static int __init init_hw_perf_events(void)
{
struct x86_pmu_quirk *quirk;
@@ -1898,6 +1951,11 @@ static int __init init_hw_perf_events(void)
pr_info("... fixed-purpose events: %d\n", x86_pmu.num_counters_fixed);
pr_info("... event mask: %016Lx\n", x86_pmu.intel_ctrl);
+ if (!x86_pmu.read)
+ x86_pmu.read = _x86_pmu_read;
+
+ x86_pmu_static_call_update();
+
/*
* Install callbacks. Core will call them for each online
* cpu.
@@ -1934,11 +1992,9 @@ out:
}
early_initcall(init_hw_perf_events);
-static inline void x86_pmu_read(struct perf_event *event)
+static void x86_pmu_read(struct perf_event *event)
{
- if (x86_pmu.read)
- return x86_pmu.read(event);
- x86_perf_event_update(event);
+ static_call(x86_pmu_read)(event);
}
/*
@@ -2015,7 +2071,7 @@ static int x86_pmu_commit_txn(struct pmu *pmu)
if (!x86_pmu_initialized())
return -EAGAIN;
- ret = x86_pmu.schedule_events(cpuc, n, assign);
+ ret = static_call(x86_pmu_schedule_events)(cpuc, n, assign);
if (ret)
return ret;
@@ -2308,15 +2364,13 @@ static const struct attribute_group *x86_pmu_attr_groups[] = {
static void x86_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
{
- if (x86_pmu.sched_task)
- x86_pmu.sched_task(ctx, sched_in);
+ static_call_cond(x86_pmu_sched_task)(ctx, sched_in);
}
static void x86_pmu_swap_task_ctx(struct perf_event_context *prev,
struct perf_event_context *next)
{
- if (x86_pmu.swap_task_ctx)
- x86_pmu.swap_task_ctx(prev, next);
+ static_call_cond(x86_pmu_swap_task_ctx)(prev, next);
}
void perf_check_microcode(void)
diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h
new file mode 100644
index 000000000000..c37f11999d0c
--- /dev/null
+++ b/arch/x86/include/asm/static_call.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_STATIC_CALL_H
+#define _ASM_STATIC_CALL_H
+
+#include <asm/text-patching.h>
+
+/*
+ * For CONFIG_HAVE_STATIC_CALL_INLINE, this is a temporary trampoline which
+ * uses the current value of the key->func pointer to do an indirect jump to
+ * the function. This trampoline is only used during boot, before the call
+ * sites get patched by static_call_update(). The name of this trampoline has
+ * a magical aspect: objtool uses it to find static call sites so it can create
+ * the .static_call_sites section.
+ *
+ * For CONFIG_HAVE_STATIC_CALL, this is a permanent trampoline which
+ * does a direct jump to the function. The direct jump gets patched by
+ * static_call_update().
+ *
+ * Having the trampoline in a special section forces GCC to emit a JMP.d32 when
+ * it does tail-call optimization on the call; since you cannot compute the
+ * relative displacement across sections.
+ */
+
+#define __ARCH_DEFINE_STATIC_CALL_TRAMP(name, insns) \
+ asm(".pushsection .static_call.text, \"ax\" \n" \
+ ".align 4 \n" \
+ ".globl " STATIC_CALL_TRAMP_STR(name) " \n" \
+ STATIC_CALL_TRAMP_STR(name) ": \n" \
+ insns " \n" \
+ ".type " STATIC_CALL_TRAMP_STR(name) ", @function \n" \
+ ".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \
+ ".popsection \n")
+
+#define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func) \
+ __ARCH_DEFINE_STATIC_CALL_TRAMP(name, ".byte 0xe9; .long " #func " - (. + 4)")
+
+#define ARCH_DEFINE_STATIC_CALL_NULL_TRAMP(name) \
+ __ARCH_DEFINE_STATIC_CALL_TRAMP(name, "ret; nop; nop; nop; nop")
+
+#endif /* _ASM_STATIC_CALL_H */
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 6593b42cb379..b7421780e4e9 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -53,6 +53,9 @@ extern void text_poke_finish(void);
#define INT3_INSN_SIZE 1
#define INT3_INSN_OPCODE 0xCC
+#define RET_INSN_SIZE 1
+#define RET_INSN_OPCODE 0xC3
+
#define CALL_INSN_SIZE 5
#define CALL_INSN_OPCODE 0xE8
@@ -73,6 +76,7 @@ static __always_inline int text_opcode_size(u8 opcode)
switch(opcode) {
__CASE(INT3);
+ __CASE(RET);
__CASE(CALL);
__CASE(JMP32);
__CASE(JMP8);
@@ -141,11 +145,26 @@ void int3_emulate_push(struct pt_regs *regs, unsigned long val)
}
static __always_inline
+unsigned long int3_emulate_pop(struct pt_regs *regs)
+{
+ unsigned long val = *(unsigned long *)regs->sp;
+ regs->sp += sizeof(unsigned long);
+ return val;
+}
+
+static __always_inline
void int3_emulate_call(struct pt_regs *regs, unsigned long func)
{
int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
int3_emulate_jmp(regs, func);
}
+
+static __always_inline
+void int3_emulate_ret(struct pt_regs *regs)
+{
+ unsigned long ip = int3_emulate_pop(regs);
+ int3_emulate_jmp(regs, ip);
+}
#endif /* !CONFIG_UML_X86 */
#endif /* _ASM_X86_TEXT_PATCHING_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index e77261db2391..de09af019e23 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -68,6 +68,7 @@ obj-y += tsc.o tsc_msr.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
obj-y += irqflags.o
+obj-y += static_call.o
obj-y += process.o
obj-y += fpu/
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index cdaab30880b9..4adbe65afe23 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1103,6 +1103,10 @@ noinstr int poke_int3_handler(struct pt_regs *regs)
*/
goto out_put;
+ case RET_INSN_OPCODE:
+ int3_emulate_ret(regs);
+ break;
+
case CALL_INSN_OPCODE:
int3_emulate_call(regs, (long)ip + tp->rel32);
break;
@@ -1277,6 +1281,7 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
switch (tp->opcode) {
case INT3_INSN_OPCODE:
+ case RET_INSN_OPCODE:
break;
case CALL_INSN_OPCODE:
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 40f380461e6d..c068e21c2c40 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -18,6 +18,7 @@
#include <linux/ftrace.h>
#include <linux/frame.h>
#include <linux/pgtable.h>
+#include <linux/static_call.h>
#include <asm/text-patching.h>
#include <asm/cacheflush.h>
@@ -210,7 +211,8 @@ static int copy_optimized_instructions(u8 *dest, u8 *src, u8 *real)
/* Check whether the address range is reserved */
if (ftrace_text_reserved(src, src + len - 1) ||
alternatives_text_reserved(src, src + len - 1) ||
- jump_label_text_reserved(src, src + len - 1))
+ jump_label_text_reserved(src, src + len - 1) ||
+ static_call_text_reserved(src, src + len - 1))
return -EBUSY;
return len;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d41be0df72f8..fa16b906ea3f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -19,6 +19,7 @@
#include <linux/hugetlb.h>
#include <linux/tboot.h>
#include <linux/usb/xhci-dbgp.h>
+#include <linux/static_call.h>
#include <uapi/linux/mount.h>
@@ -849,6 +850,7 @@ void __init setup_arch(char **cmdline_p)
early_cpu_init();
arch_init_ideal_nops();
jump_label_init();
+ static_call_init();
early_ioremap_init();
setup_olpc_ofw_pgd();
diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
new file mode 100644
index 000000000000..ca9a380d9c0b
--- /dev/null
+++ b/arch/x86/kernel/static_call.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/static_call.h>
+#include <linux/memory.h>
+#include <linux/bug.h>
+#include <asm/text-patching.h>
+
+enum insn_type {
+ CALL = 0, /* site call */
+ NOP = 1, /* site cond-call */
+ JMP = 2, /* tramp / site tail-call */
+ RET = 3, /* tramp / site cond-tail-call */
+};
+
+static void __ref __static_call_transform(void *insn, enum insn_type type, void *func)
+{
+ int size = CALL_INSN_SIZE;
+ const void *code;
+
+ switch (type) {
+ case CALL:
+ code = text_gen_insn(CALL_INSN_OPCODE, insn, func);
+ break;
+
+ case NOP:
+ code = ideal_nops[NOP_ATOMIC5];
+ break;
+
+ case JMP:
+ code = text_gen_insn(JMP32_INSN_OPCODE, insn, func);
+ break;
+
+ case RET:
+ code = text_gen_insn(RET_INSN_OPCODE, insn, func);
+ size = RET_INSN_SIZE;
+ break;
+ }
+
+ if (memcmp(insn, code, size) == 0)
+ return;
+
+ if (unlikely(system_state == SYSTEM_BOOTING))
+ return text_poke_early(insn, code, size);
+
+ text_poke_bp(insn, code, size, NULL);
+}
+
+static void __static_call_validate(void *insn, bool tail)
+{
+ u8 opcode = *(u8 *)insn;
+
+ if (tail) {
+ if (opcode == JMP32_INSN_OPCODE ||
+ opcode == RET_INSN_OPCODE)
+ return;
+ } else {
+ if (opcode == CALL_INSN_OPCODE ||
+ !memcmp(insn, ideal_nops[NOP_ATOMIC5], 5))
+ return;
+ }
+
+ /*
+ * If we ever trigger this, our text is corrupt, we'll probably not live long.
+ */
+ WARN_ONCE(1, "unexpected static_call insn opcode 0x%x at %pS\n", opcode, insn);
+}
+
+static inline enum insn_type __sc_insn(bool null, bool tail)
+{
+ /*
+ * Encode the following table without branches:
+ *
+ * tail null insn
+ * -----+-------+------
+ * 0 | 0 | CALL
+ * 0 | 1 | NOP
+ * 1 | 0 | JMP
+ * 1 | 1 | RET
+ */
+ return 2*tail + null;
+}
+
+void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
+{
+ mutex_lock(&text_mutex);
+
+ if (tramp) {
+ __static_call_validate(tramp, true);
+ __static_call_transform(tramp, __sc_insn(!func, true), func);
+ }
+
+ if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site) {
+ __static_call_validate(site, tail);
+ __static_call_transform(site, __sc_insn(!func, tail), func);
+ }
+
+ mutex_unlock(&text_mutex);
+}
+EXPORT_SYMBOL_GPL(arch_static_call_transform);
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 45d72447df84..bf9e0adb5b7e 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -136,6 +136,7 @@ SECTIONS
ENTRY_TEXT
ALIGN_ENTRY_TEXT_END
SOFTIRQENTRY_TEXT
+ STATIC_CALL_TEXT
*(.fixup)
*(.gnu.warning)
generated by cgit v1.2.3 (git 2.39.0) at 2025-02-13 04:27:01 +0300