Merge tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Thomas Gleixner:

 - Improve retpoline code patching by separating it from alternatives
   which reduces memory footprint and allows to do better optimizations
   in the actual runtime patching.

 - Add proper retpoline support for x86/BPF

 - Address noinstr warnings in x86/kvm, lockdep and paravirtualization
   code

 - Add support to handle pv_opsindirect calls in the noinstr analysis

 - Classify symbols upfront and cache the result to avoid redundant
   str*cmp() invocations.

 - Add a CFI hash to reduce memory consumption which also reduces
   runtime on a allyesconfig by ~50%

 - Adjust XEN code to make objtool handling more robust and as a side
   effect to prevent text fragmentation due to placement of the
   hypercall page.

* tag 'objtool-core-2021-10-31' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
  bpf,x86: Respect X86_FEATURE_RETPOLINE*
  bpf,x86: Simplify computing label offsets
  x86,bugs: Unconditionally allow spectre_v2=retpoline,amd
  x86/alternative: Add debug prints to apply_retpolines()
  x86/alternative: Try inline spectre_v2=retpoline,amd
  x86/alternative: Handle Jcc __x86_indirect_thunk_\reg
  x86/alternative: Implement .retpoline_sites support
  x86/retpoline: Create a retpoline thunk array
  x86/retpoline: Move the retpoline thunk declarations to nospec-branch.h
  x86/asm: Fixup odd GEN-for-each-reg.h usage
  x86/asm: Fix register order
  x86/retpoline: Remove unused replacement symbols
  objtool,x86: Replace alternatives with .retpoline_sites
  objtool: Shrink struct instruction
  objtool: Explicitly avoid self modifying code in .altinstr_replacement
  objtool: Classify symbols
  objtool: Support pv_opsindirect calls for noinstr
  x86/xen: Rework the xen_{cpu,irq,mmu}_opsarrays
  x86/xen: Mark xen_force_evtchn_callback() noinstr
  x86/xen: Make irq_disable() noinstr
  ...

Author: torvalds

arch/um/kernel/um_arch.c

@@ -421,6 +421,10 @@ void __init check_bugs(void)
 	os_check_bugs();
 }
 
+void apply_retpolines(s32 *start, s32 *end)
+{
+}
+
 void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
 {
 }

arch/x86/include/asm/GEN-for-each-reg.h

@@ -1,11 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * These are in machine order; things rely on that.
+ */
 #ifdef CONFIG_64BIT
 GEN(rax)
-GEN(rbx)
 GEN(rcx)
 GEN(rdx)
+GEN(rbx)
+GEN(rsp)
+GEN(rbp)
 GEN(rsi)
 GEN(rdi)
-GEN(rbp)
 GEN(r8)
 GEN(r9)
 GEN(r10)
@@ -16,10 +21,11 @@ GEN(r14)
 GEN(r15)
 #else
 GEN(eax)
-GEN(ebx)
 GEN(ecx)
 GEN(edx)
+GEN(ebx)
+GEN(esp)
+GEN(ebp)
 GEN(esi)
 GEN(edi)
-GEN(ebp)
 #endif

arch/x86/include/asm/alternative.h

@@ -75,6 +75,7 @@ extern int alternatives_patched;
 
 extern void alternative_instructions(void);
 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+extern void apply_retpolines(s32 *start, s32 *end);
 
 struct module;
 

arch/x86/include/asm/asm-prototypes.h

@@ -17,21 +17,3 @@
 extern void cmpxchg8b_emu(void);
 #endif
 
-#ifdef CONFIG_RETPOLINE
-
-#undef GEN
-#define GEN(reg) \
-	extern asmlinkage void __x86_indirect_thunk_ ## reg (void);
-#include <asm/GEN-for-each-reg.h>
-
-#undef GEN
-#define GEN(reg) \
-	extern asmlinkage void __x86_indirect_alt_call_ ## reg (void);
-#include <asm/GEN-for-each-reg.h>
-
-#undef GEN
-#define GEN(reg) \
-	extern asmlinkage void __x86_indirect_alt_jmp_ ## reg (void);
-#include <asm/GEN-for-each-reg.h>
-
-#endif /* CONFIG_RETPOLINE */

arch/x86/include/asm/nospec-branch.h

@@ -5,12 +5,15 @@
 
 #include <linux/static_key.h>
 #include <linux/objtool.h>
+#include <linux/linkage.h>
 
 #include <asm/alternative.h>
 #include <asm/cpufeatures.h>
 #include <asm/msr-index.h>
 #include <asm/unwind_hints.h>
 
+#define RETPOLINE_THUNK_SIZE	32
+
 /*
  * Fill the CPU return stack buffer.
  *
@@ -118,6 +121,16 @@
 	".popsection\n\t"
 
 #ifdef CONFIG_RETPOLINE
+
+typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
+
+#define GEN(reg) \
+	extern retpoline_thunk_t __x86_indirect_thunk_ ## reg;
+#include <asm/GEN-for-each-reg.h>
+#undef GEN
+
+extern retpoline_thunk_t __x86_indirect_thunk_array[];
+
 #ifdef CONFIG_X86_64
 
 /*
@@ -303,63 +316,4 @@ static inline void mds_idle_clear_cpu_buffers(void)
 
 #endif /* __ASSEMBLY__ */
 
-/*
- * Below is used in the eBPF JIT compiler and emits the byte sequence
- * for the following assembly:
- *
- * With retpolines configured:
- *
- *    callq do_rop
- *  spec_trap:
- *    pause
- *    lfence
- *    jmp spec_trap
- *  do_rop:
- *    mov %rcx,(%rsp) for x86_64
- *    mov %edx,(%esp) for x86_32
- *    retq
- *
- * Without retpolines configured:
- *
- *    jmp *%rcx for x86_64
- *    jmp *%edx for x86_32
- */
-#ifdef CONFIG_RETPOLINE
-# ifdef CONFIG_X86_64
-#  define RETPOLINE_RCX_BPF_JIT_SIZE	17
-#  define RETPOLINE_RCX_BPF_JIT()				\
-do {								\
-	EMIT1_off32(0xE8, 7);	 /* callq do_rop */		\
-	/* spec_trap: */					\
-	EMIT2(0xF3, 0x90);       /* pause */			\
-	EMIT3(0x0F, 0xAE, 0xE8); /* lfence */			\
-	EMIT2(0xEB, 0xF9);       /* jmp spec_trap */		\
-	/* do_rop: */						\
-	EMIT4(0x48, 0x89, 0x0C, 0x24); /* mov %rcx,(%rsp) */	\
-	EMIT1(0xC3);             /* retq */			\
-} while (0)
-# else /* !CONFIG_X86_64 */
-#  define RETPOLINE_EDX_BPF_JIT()				\
-do {								\
-	EMIT1_off32(0xE8, 7);	 /* call do_rop */		\
-	/* spec_trap: */					\
-	EMIT2(0xF3, 0x90);       /* pause */			\
-	EMIT3(0x0F, 0xAE, 0xE8); /* lfence */			\
-	EMIT2(0xEB, 0xF9);       /* jmp spec_trap */		\
-	/* do_rop: */						\
-	EMIT3(0x89, 0x14, 0x24); /* mov %edx,(%esp) */		\
-	EMIT1(0xC3);             /* ret */			\
-} while (0)
-# endif
-#else /* !CONFIG_RETPOLINE */
-# ifdef CONFIG_X86_64
-#  define RETPOLINE_RCX_BPF_JIT_SIZE	2
-#  define RETPOLINE_RCX_BPF_JIT()				\
-	EMIT2(0xFF, 0xE1);       /* jmp *%rcx */
-# else /* !CONFIG_X86_64 */
-#  define RETPOLINE_EDX_BPF_JIT()				\
-	EMIT2(0xFF, 0xE2)        /* jmp *%edx */
-# endif
-#endif
-
 #endif /* _ASM_X86_NOSPEC_BRANCH_H_ */

arch/x86/include/asm/paravirt.h

@@ -52,11 +52,11 @@ void __init paravirt_set_cap(void);
 /* The paravirtualized I/O functions */
 static inline void slow_down_io(void)
 {
-	pv_ops.cpu.io_delay();
+	PVOP_VCALL0(cpu.io_delay);
 #ifdef REALLY_SLOW_IO
-	pv_ops.cpu.io_delay();
-	pv_ops.cpu.io_delay();
-	pv_ops.cpu.io_delay();
+	PVOP_VCALL0(cpu.io_delay);
+	PVOP_VCALL0(cpu.io_delay);
+	PVOP_VCALL0(cpu.io_delay);
 #endif
 }
 
@@ -113,12 +113,12 @@ static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
 /*
  * These special macros can be used to get or set a debugging register
  */
-static inline unsigned long paravirt_get_debugreg(int reg)
+static __always_inline unsigned long paravirt_get_debugreg(int reg)
 {
 	return PVOP_CALL1(unsigned long, cpu.get_debugreg, reg);
 }
 #define get_debugreg(var, reg) var = paravirt_get_debugreg(reg)
-static inline void set_debugreg(unsigned long val, int reg)
+static __always_inline void set_debugreg(unsigned long val, int reg)
 {
 	PVOP_VCALL2(cpu.set_debugreg, reg, val);
 }
@@ -133,14 +133,14 @@ static inline void write_cr0(unsigned long x)
 	PVOP_VCALL1(cpu.write_cr0, x);
 }
 
-static inline unsigned long read_cr2(void)
+static __always_inline unsigned long read_cr2(void)
 {
 	return PVOP_ALT_CALLEE0(unsigned long, mmu.read_cr2,
 				"mov %%cr2, %%rax;",
 				ALT_NOT(X86_FEATURE_XENPV));
 }
 
-static inline void write_cr2(unsigned long x)
+static __always_inline void write_cr2(unsigned long x)
 {
 	PVOP_VCALL1(mmu.write_cr2, x);
 }
@@ -653,10 +653,10 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu);
  * functions.
  */
 #define PV_THUNK_NAME(func) "__raw_callee_save_" #func
-#define PV_CALLEE_SAVE_REGS_THUNK(func)					\
+#define __PV_CALLEE_SAVE_REGS_THUNK(func, section)			\
 	extern typeof(func) __raw_callee_save_##func;			\
 									\
-	asm(".pushsection .text;"					\
+	asm(".pushsection " section ", \"ax\";"				\
 	    ".globl " PV_THUNK_NAME(func) ";"				\
 	    ".type " PV_THUNK_NAME(func) ", @function;"			\
 	    PV_THUNK_NAME(func) ":"					\
@@ -669,6 +669,9 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu);
 	    ".size " PV_THUNK_NAME(func) ", .-" PV_THUNK_NAME(func) ";"	\
 	    ".popsection")
 
+#define PV_CALLEE_SAVE_REGS_THUNK(func)			\
+	__PV_CALLEE_SAVE_REGS_THUNK(func, ".text")
+
 /* Get a reference to a callee-save function */
 #define PV_CALLEE_SAVE(func)						\
 	((struct paravirt_callee_save) { __raw_callee_save_##func })
@@ -678,23 +681,23 @@ bool __raw_callee_save___native_vcpu_is_preempted(long cpu);
 	((struct paravirt_callee_save) { func })
 
 #ifdef CONFIG_PARAVIRT_XXL
-static inline notrace unsigned long arch_local_save_flags(void)
+static __always_inline unsigned long arch_local_save_flags(void)
 {
 	return PVOP_ALT_CALLEE0(unsigned long, irq.save_fl, "pushf; pop %%rax;",
 				ALT_NOT(X86_FEATURE_XENPV));
 }
 
-static inline notrace void arch_local_irq_disable(void)
+static __always_inline void arch_local_irq_disable(void)
 {
 	PVOP_ALT_VCALLEE0(irq.irq_disable, "cli;", ALT_NOT(X86_FEATURE_XENPV));
 }
 
-static inline notrace void arch_local_irq_enable(void)
+static __always_inline void arch_local_irq_enable(void)
 {
 	PVOP_ALT_VCALLEE0(irq.irq_enable, "sti;", ALT_NOT(X86_FEATURE_XENPV));
 }
 
-static inline notrace unsigned long arch_local_irq_save(void)
+static __always_inline unsigned long arch_local_irq_save(void)
 {
 	unsigned long f;
 

arch/x86/include/asm/ptrace.h

@@ -181,7 +181,7 @@ static inline bool any_64bit_mode(struct pt_regs *regs)
 #define current_user_stack_pointer()	current_pt_regs()->sp
 #define compat_user_stack_pointer()	current_pt_regs()->sp
 
-static inline bool ip_within_syscall_gap(struct pt_regs *regs)
+static __always_inline bool ip_within_syscall_gap(struct pt_regs *regs)
 {
 	bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 &&
 		    regs->ip <  (unsigned long)entry_SYSCALL_64_safe_stack);

arch/x86/include/asm/xen/hypercall.h

@@ -308,13 +308,13 @@ HYPERVISOR_platform_op(struct xen_platform_op *op)
 	return _hypercall1(int, platform_op, op);
 }
 
-static inline int
+static __always_inline int
 HYPERVISOR_set_debugreg(int reg, unsigned long value)
 {
 	return _hypercall2(int, set_debugreg, reg, value);
 }
 
-static inline unsigned long
+static __always_inline unsigned long
 HYPERVISOR_get_debugreg(int reg)
 {
 	return _hypercall1(unsigned long, get_debugreg, reg);
@@ -358,7 +358,7 @@ HYPERVISOR_event_channel_op(int cmd, void *arg)
 	return _hypercall2(int, event_channel_op, cmd, arg);
 }
 
-static inline int
+static __always_inline int
 HYPERVISOR_xen_version(int cmd, void *arg)
 {
 	return _hypercall2(int, xen_version, cmd, arg);