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x86/jump-label: Remove support for custom text poker

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There are only two types of text poking: early and breakpoint based. The use
of a function pointer to perform text poking complicates the code and is
probably inefficient due to the use of indirect branches.

Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-13-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Nadav Amit 2019-04-25 17:11:32 -07:00 committed by Ingo Molnar
parent f2c65fb322
commit bb0a008d6a
1 changed files with 10 additions and 16 deletions
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26
arch/x86/kernel/jump_label.c
View file

@ -37,7 +37,6 @@ static void bug_at(unsigned char *ip, int line)
static void __ref __jump_label_transform(struct jump_entry *entry, static void __ref __jump_label_transform(struct jump_entry *entry,
enum jump_label_type type, enum jump_label_type type,
void *(*poker)(void *, const void *, size_t),
int init) int init)
{ {
union jump_code_union jmp; union jump_code_union jmp;
@ -50,14 +49,6 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
jmp.offset = jump_entry_target(entry) - jmp.offset = jump_entry_target(entry) -
(jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE); (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
/*
* As long as only a single processor is running and the code is still
* not marked as RO, text_poke_early() can be used; Checking that
* system_state is SYSTEM_BOOTING guarantees it.
*/
if (system_state == SYSTEM_BOOTING)
poker = text_poke_early;
if (type == JUMP_LABEL_JMP) { if (type == JUMP_LABEL_JMP) {
if (init) { if (init) {
expect = default_nop; line = __LINE__; expect = default_nop; line = __LINE__;
@ -80,16 +71,19 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
bug_at((void *)jump_entry_code(entry), line); bug_at((void *)jump_entry_code(entry), line);
/* /*
* Make text_poke_bp() a default fallback poker. * As long as only a single processor is running and the code is still
* not marked as RO, text_poke_early() can be used; Checking that
* system_state is SYSTEM_BOOTING guarantees it. It will be set to
* SYSTEM_SCHEDULING before other cores are awaken and before the
* code is write-protected.
* *
* At the time the change is being done, just ignore whether we * At the time the change is being done, just ignore whether we
* are doing nop -> jump or jump -> nop transition, and assume * are doing nop -> jump or jump -> nop transition, and assume
* always nop being the 'currently valid' instruction * always nop being the 'currently valid' instruction
*
*/ */
if (poker) { if (init || system_state == SYSTEM_BOOTING) {
(*poker)((void *)jump_entry_code(entry), code, text_poke_early((void *)jump_entry_code(entry), code,
JUMP_LABEL_NOP_SIZE); JUMP_LABEL_NOP_SIZE);
return; return;
} }
@ -101,7 +95,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type) enum jump_label_type type)
{ {
mutex_lock(&text_mutex); mutex_lock(&text_mutex);
__jump_label_transform(entry, type, NULL, 0); __jump_label_transform(entry, type, 0);
mutex_unlock(&text_mutex); mutex_unlock(&text_mutex);
} }
@ -131,5 +125,5 @@ __init_or_module void arch_jump_label_transform_static(struct jump_entry *entry,
jlstate = JL_STATE_NO_UPDATE; jlstate = JL_STATE_NO_UPDATE;
} }
if (jlstate == JL_STATE_UPDATE) if (jlstate == JL_STATE_UPDATE)
__jump_label_transform(entry, type, text_poke_early, 1); __jump_label_transform(entry, type, 1);
} }