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x86/int3: Ensure that poke_int3_handler() is not traced

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In order to ensure poke_int3_handler() is completely self contained -- this
is called while modifying other text, imagine the fun of hitting another
INT3 -- ensure that everything it uses is not traced.

The primary means here is to force inlining; bsearch() is notrace because
all of lib/ is.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135313.410702173@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-01-21 15:53:09 +01:00
parent d77290507a
commit 4979fb53ab
3 changed files with 14 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/ptrace.h
View File

@ -123,7 +123,7 @@ static inline void regs_set_return_value(struct pt_regs *regs, unsigned long rc)
* On x86_64, vm86 mode is mercifully nonexistent, and we don't need * On x86_64, vm86 mode is mercifully nonexistent, and we don't need
* the extra check. * the extra check.
*/ */
static inline int user_mode(struct pt_regs *regs) static __always_inline int user_mode(struct pt_regs *regs)
{ {
#ifdef CONFIG_X86_32 #ifdef CONFIG_X86_32
return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL; return ((regs->cs & SEGMENT_RPL_MASK) | (regs->flags & X86_VM_MASK)) >= USER_RPL;

11
arch/x86/include/asm/text-patching.h
View File

@ -64,7 +64,7 @@ extern void text_poke_finish(void);
#define DISP32_SIZE 4 #define DISP32_SIZE 4
static inline int text_opcode_size(u8 opcode) static __always_inline int text_opcode_size(u8 opcode)
{ {
int size = 0; int size = 0;
@ -118,12 +118,14 @@ extern __ro_after_init struct mm_struct *poking_mm;
extern __ro_after_init unsigned long poking_addr; extern __ro_after_init unsigned long poking_addr;
#ifndef CONFIG_UML_X86 #ifndef CONFIG_UML_X86
static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip) static __always_inline
void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
{ {
regs->ip = ip; regs->ip = ip;
} }
static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val) static __always_inline
void int3_emulate_push(struct pt_regs *regs, unsigned long val)
{ {
/* /*
* The int3 handler in entry_64.S adds a gap between the * The int3 handler in entry_64.S adds a gap between the
@ -138,7 +140,8 @@ static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
*(unsigned long *)regs->sp = val; *(unsigned long *)regs->sp = val;
} }
static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func) 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_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
int3_emulate_jmp(regs, func); int3_emulate_jmp(regs, func);

13
arch/x86/kernel/alternative.c
View File

@ -1011,7 +1011,8 @@ struct bp_patching_desc {
static struct bp_patching_desc *bp_desc; static struct bp_patching_desc *bp_desc;
static inline struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp) static __always_inline
struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp)
{ {
struct bp_patching_desc *desc = READ_ONCE(*descp); /* rcu_dereference */ struct bp_patching_desc *desc = READ_ONCE(*descp); /* rcu_dereference */
@ -1021,18 +1022,18 @@ static inline struct bp_patching_desc *try_get_desc(struct bp_patching_desc **de
return desc; return desc;
} }
static inline void put_desc(struct bp_patching_desc *desc) static __always_inline void put_desc(struct bp_patching_desc *desc)
{ {
smp_mb__before_atomic(); smp_mb__before_atomic();
atomic_dec(&desc->refs); atomic_dec(&desc->refs);
} }
static inline void *text_poke_addr(struct text_poke_loc *tp) static __always_inline void *text_poke_addr(struct text_poke_loc *tp)
{ {
return _stext + tp->rel_addr; return _stext + tp->rel_addr;
} }
static int notrace patch_cmp(const void *key, const void *elt) static int noinstr patch_cmp(const void *key, const void *elt)
{ {
struct text_poke_loc *tp = (struct text_poke_loc *) elt; struct text_poke_loc *tp = (struct text_poke_loc *) elt;
@ -1042,9 +1043,8 @@ static int notrace patch_cmp(const void *key, const void *elt)
return 1; return 1;
return 0; return 0;
} }
NOKPROBE_SYMBOL(patch_cmp);
int notrace poke_int3_handler(struct pt_regs *regs) int noinstr poke_int3_handler(struct pt_regs *regs)
{ {
struct bp_patching_desc *desc; struct bp_patching_desc *desc;
struct text_poke_loc *tp; struct text_poke_loc *tp;
@ -1118,7 +1118,6 @@ out_put:
put_desc(desc); put_desc(desc);
return ret; return ret;
} }
NOKPROBE_SYMBOL(poke_int3_handler);
#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_poke_loc)) #define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_poke_loc))
static struct text_poke_loc tp_vec[TP_VEC_MAX]; static struct text_poke_loc tp_vec[TP_VEC_MAX];