The following commit has been merged into the x86/core branch of tip:
Commit-ID: 72e213a7ccf9dc78a85eecee8dc8170762ed876c
Gitweb: https://git.kernel.org/tip/72e213a7ccf9dc78a85eecee8dc8170762ed876c
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 07 Feb 2025 13:15:31 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 14 Feb 2025 10:32:04 +01:00
x86/ibt: Clean up is_endbr()
Pretty much every caller of is_endbr() actually wants to test something at an
address and ends up doing get_kernel_nofault(). Fold the lot into a more
convenient helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20250207122546.181367417@xxxxxxxxxxxxx
---
arch/x86/events/core.c | 2 +-
arch/x86/include/asm/ftrace.h | 16 ++--------------
arch/x86/include/asm/ibt.h | 5 +++--
arch/x86/kernel/alternative.c | 20 ++++++++++++++------
arch/x86/kernel/kprobes/core.c | 11 +----------
arch/x86/net/bpf_jit_comp.c | 4 ++--
kernel/trace/bpf_trace.c | 21 ++++-----------------
7 files changed, 27 insertions(+), 52 deletions(-)
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 8f218ac..ff4e84a 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2844,7 +2844,7 @@ static bool is_uprobe_at_func_entry(struct pt_regs *regs)
return true;
/* endbr64 (64-bit only) */
- if (user_64bit_mode(regs) && is_endbr(*(u32 *)auprobe->insn))
+ if (user_64bit_mode(regs) && is_endbr((u32 *)auprobe->insn))
return true;
return false;
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index f9cb4d0..f226524 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -36,21 +36,9 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
static inline unsigned long arch_ftrace_get_symaddr(unsigned long fentry_ip)
{
-#ifdef CONFIG_X86_KERNEL_IBT
- u32 instr;
-
- /* We want to be extra safe in case entry ip is on the page edge,
- * but otherwise we need to avoid get_kernel_nofault()'s overhead.
- */
- if ((fentry_ip & ~PAGE_MASK) < ENDBR_INSN_SIZE) {
- if (get_kernel_nofault(instr, (u32 *)(fentry_ip - ENDBR_INSN_SIZE)))
- return fentry_ip;
- } else {
- instr = *(u32 *)(fentry_ip - ENDBR_INSN_SIZE);
- }
- if (is_endbr(instr))
+ if (is_endbr((void*)(fentry_ip - ENDBR_INSN_SIZE)))
fentry_ip -= ENDBR_INSN_SIZE;
-#endif
+
return fentry_ip;
}
#define ftrace_get_symaddr(fentry_ip) arch_ftrace_get_symaddr(fentry_ip)
diff --git a/arch/x86/include/asm/ibt.h b/arch/x86/include/asm/ibt.h
index 1e59581..d955e0d 100644
--- a/arch/x86/include/asm/ibt.h
+++ b/arch/x86/include/asm/ibt.h
@@ -65,7 +65,7 @@ static inline __attribute_const__ u32 gen_endbr_poison(void)
return 0x001f0f66; /* osp nopl (%rax) */
}
-static inline bool is_endbr(u32 val)
+static inline bool __is_endbr(u32 val)
{
if (val == gen_endbr_poison())
return true;
@@ -74,6 +74,7 @@ static inline bool is_endbr(u32 val)
return val == gen_endbr();
}
+extern __noendbr bool is_endbr(u32 *val);
extern __noendbr u64 ibt_save(bool disable);
extern __noendbr void ibt_restore(u64 save);
@@ -98,7 +99,7 @@ extern __noendbr void ibt_restore(u64 save);
#define __noendbr
-static inline bool is_endbr(u32 val) { return false; }
+static inline bool is_endbr(u32 *val) { return false; }
static inline u64 ibt_save(bool disable) { return 0; }
static inline void ibt_restore(u64 save) { }
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 8b66a55..9a252bb 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -852,16 +852,24 @@ void __init_or_module noinline apply_returns(s32 *start, s32 *end) { }
#ifdef CONFIG_X86_KERNEL_IBT
+__noendbr bool is_endbr(u32 *val)
+{
+ u32 endbr;
+
+ __get_kernel_nofault(&endbr, val, u32, Efault);
+ return __is_endbr(endbr);
+
+Efault:
+ return false;
+}
+
static void poison_cfi(void *addr);
static void __init_or_module poison_endbr(void *addr, bool warn)
{
- u32 endbr, poison = gen_endbr_poison();
-
- if (WARN_ON_ONCE(get_kernel_nofault(endbr, addr)))
- return;
+ u32 poison = gen_endbr_poison();
- if (!is_endbr(endbr)) {
+ if (!is_endbr(addr)) {
WARN_ON_ONCE(warn);
return;
}
@@ -988,7 +996,7 @@ static u32 cfi_seed __ro_after_init;
static u32 cfi_rehash(u32 hash)
{
hash ^= cfi_seed;
- while (unlikely(is_endbr(hash) || is_endbr(-hash))) {
+ while (unlikely(__is_endbr(hash) || __is_endbr(-hash))) {
bool lsb = hash & 1;
hash >>= 1;
if (lsb)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 72e6a45..09608fd 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -373,16 +373,7 @@ out:
kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset,
bool *on_func_entry)
{
- u32 insn;
-
- /*
- * Since 'addr' is not guaranteed to be safe to access, use
- * copy_from_kernel_nofault() to read the instruction:
- */
- if (copy_from_kernel_nofault(&insn, (void *)addr, sizeof(u32)))
- return NULL;
-
- if (is_endbr(insn)) {
+ if (is_endbr((u32 *)addr)) {
*on_func_entry = !offset || offset == 4;
if (*on_func_entry)
offset = 4;
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a43fc5a..f36508b 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -641,7 +641,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
* See emit_prologue(), for IBT builds the trampoline hook is preceded
* with an ENDBR instruction.
*/
- if (is_endbr(*(u32 *)ip))
+ if (is_endbr(ip))
ip += ENDBR_INSN_SIZE;
return __bpf_arch_text_poke(ip, t, old_addr, new_addr);
@@ -3036,7 +3036,7 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *rw_im
/* skip patched call instruction and point orig_call to actual
* body of the kernel function.
*/
- if (is_endbr(*(u32 *)orig_call))
+ if (is_endbr(orig_call))
orig_call += ENDBR_INSN_SIZE;
orig_call += X86_PATCH_SIZE;
}
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index adc9475..997fb2a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1038,27 +1038,14 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
.arg1_type = ARG_PTR_TO_CTX,
};
-#ifdef CONFIG_X86_KERNEL_IBT
-static unsigned long get_entry_ip(unsigned long fentry_ip)
+static inline unsigned long get_entry_ip(unsigned long fentry_ip)
{
- u32 instr;
-
- /* We want to be extra safe in case entry ip is on the page edge,
- * but otherwise we need to avoid get_kernel_nofault()'s overhead.
- */
- if ((fentry_ip & ~PAGE_MASK) < ENDBR_INSN_SIZE) {
- if (get_kernel_nofault(instr, (u32 *)(fentry_ip - ENDBR_INSN_SIZE)))
- return fentry_ip;
- } else {
- instr = *(u32 *)(fentry_ip - ENDBR_INSN_SIZE);
- }
- if (is_endbr(instr))
+#ifdef CONFIG_X86_KERNEL_IBT
+ if (is_endbr((void *)(fentry_ip - ENDBR_INSN_SIZE)))
fentry_ip -= ENDBR_INSN_SIZE;
+#endif
return fentry_ip;
}
-#else
-#define get_entry_ip(fentry_ip) fentry_ip
-#endif
BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
{
|