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SubjectRe: [PATCH v4 29/45] x86/ibt: Annotate text references
On Tue, 08 Mar 2022 16:30:40 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> Annotate away some of the generic code references. This is things
> where we take the address of a symbol for exception handling or return
> addresses (eg. context switch).

Ah, I got it. I need this annotate lines for rethook too.

Thank you,

>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/x86/entry/entry_64.S | 6 ++++++
> arch/x86/entry/entry_64_compat.S | 1 +
> arch/x86/kernel/alternative.c | 10 ++++++++--
> arch/x86/kernel/head_64.S | 4 ++++
> arch/x86/kernel/kprobes/core.c | 1 +
> arch/x86/kernel/relocate_kernel_64.S | 2 ++
> arch/x86/lib/error-inject.c | 2 ++
> arch/x86/lib/retpoline.S | 1 +
> 8 files changed, 25 insertions(+), 2 deletions(-)
>
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -277,6 +277,7 @@ SYM_FUNC_END(__switch_to_asm)
> .pushsection .text, "ax"
> SYM_CODE_START(ret_from_fork)
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR // copy_thread
> movq %rax, %rdi
> call schedule_tail /* rdi: 'prev' task parameter */
>
> @@ -569,6 +570,7 @@ SYM_CODE_END(\asmsym)
> .align 16
> .globl __irqentry_text_end
> __irqentry_text_end:
> + ANNOTATE_NOENDBR
>
> SYM_CODE_START_LOCAL(common_interrupt_return)
> SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)
> @@ -650,6 +652,7 @@ SYM_INNER_LABEL(early_xen_iret_patch, SY
> #endif
>
> SYM_INNER_LABEL(native_irq_return_iret, SYM_L_GLOBAL)
> + ANNOTATE_NOENDBR // exc_double_fault
> /*
> * This may fault. Non-paranoid faults on return to userspace are
> * handled by fixup_bad_iret. These include #SS, #GP, and #NP.
> @@ -744,6 +747,7 @@ SYM_FUNC_START(asm_load_gs_index)
> FRAME_BEGIN
> swapgs
> .Lgs_change:
> + ANNOTATE_NOENDBR // error_entry
> movl %edi, %gs
> 2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
> swapgs
> @@ -1322,6 +1326,7 @@ SYM_CODE_START(asm_exc_nmi)
> #endif
>
> repeat_nmi:
> + ANNOTATE_NOENDBR // this code
> /*
> * If there was a nested NMI, the first NMI's iret will return
> * here. But NMIs are still enabled and we can take another
> @@ -1350,6 +1355,7 @@ SYM_CODE_START(asm_exc_nmi)
> .endr
> subq $(5*8), %rsp
> end_repeat_nmi:
> + ANNOTATE_NOENDBR // this code
>
> /*
> * Everything below this point can be preempted by a nested NMI.
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -148,6 +148,7 @@ SYM_INNER_LABEL(entry_SYSENTER_compat_af
> popfq
> jmp .Lsysenter_flags_fixed
> SYM_INNER_LABEL(__end_entry_SYSENTER_compat, SYM_L_GLOBAL)
> + ANNOTATE_NOENDBR // is_sysenter_singlestep
> SYM_CODE_END(entry_SYSENTER_compat)
>
> /*
> --- a/arch/x86/kernel/alternative.c
> +++ b/arch/x86/kernel/alternative.c
> @@ -713,6 +713,7 @@ asm (
> " .pushsection .init.text, \"ax\", @progbits\n"
> " .type int3_magic, @function\n"
> "int3_magic:\n"
> + ANNOTATE_NOENDBR
> " movl $1, (%" _ASM_ARG1 ")\n"
> ASM_RET
> " .size int3_magic, .-int3_magic\n"
> @@ -724,16 +725,19 @@ extern void int3_selftest_ip(void); /* d
> static int __init
> int3_exception_notify(struct notifier_block *self, unsigned long val, void *data)
> {
> + unsigned long selftest = (unsigned long)&int3_selftest_ip;
> struct die_args *args = data;
> struct pt_regs *regs = args->regs;
>
> + OPTIMIZER_HIDE_VAR(selftest);
> +
> if (!regs || user_mode(regs))
> return NOTIFY_DONE;
>
> if (val != DIE_INT3)
> return NOTIFY_DONE;
>
> - if (regs->ip - INT3_INSN_SIZE != (unsigned long)&int3_selftest_ip)
> + if (regs->ip - INT3_INSN_SIZE != selftest)
> return NOTIFY_DONE;
>
> int3_emulate_call(regs, (unsigned long)&int3_magic);
> @@ -757,7 +761,9 @@ static void __init int3_selftest(void)
> * then trigger the INT3, padded with NOPs to match a CALL instruction
> * length.
> */
> - asm volatile ("int3_selftest_ip: int3; nop; nop; nop; nop\n\t"
> + asm volatile ("int3_selftest_ip:\n\t"
> + ANNOTATE_NOENDBR
> + " int3; nop; nop; nop; nop\n\t"
> : ASM_CALL_CONSTRAINT
> : __ASM_SEL_RAW(a, D) (&val)
> : "memory");
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -99,6 +99,7 @@ SYM_CODE_END(startup_64)
>
> SYM_CODE_START(secondary_startup_64)
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR
> /*
> * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
> * and someone has loaded a mapped page table.
> @@ -127,6 +128,7 @@ SYM_CODE_START(secondary_startup_64)
> */
> SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR
>
> /*
> * Retrieve the modifier (SME encryption mask if SME is active) to be
> @@ -192,6 +194,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_
> jmp *%rax
> 1:
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR // above
>
> /*
> * We must switch to a new descriptor in kernel space for the GDT
> @@ -299,6 +302,7 @@ SYM_INNER_LABEL(secondary_startup_64_no_
> pushq %rax # target address in negative space
> lretq
> .Lafter_lret:
> + ANNOTATE_NOENDBR
> SYM_CODE_END(secondary_startup_64)
>
> #include "verify_cpu.S"
> --- a/arch/x86/kernel/kprobes/core.c
> +++ b/arch/x86/kernel/kprobes/core.c
> @@ -1033,6 +1033,7 @@ asm(
> ".type __kretprobe_trampoline, @function\n"
> "__kretprobe_trampoline:\n"
> #ifdef CONFIG_X86_64
> + ANNOTATE_NOENDBR
> /* Push a fake return address to tell the unwinder it's a kretprobe. */
> " pushq $__kretprobe_trampoline\n"
> UNWIND_HINT_FUNC
> --- a/arch/x86/kernel/relocate_kernel_64.S
> +++ b/arch/x86/kernel/relocate_kernel_64.S
> @@ -42,6 +42,7 @@
> .code64
> SYM_CODE_START_NOALIGN(relocate_kernel)
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR
> /*
> * %rdi indirection_page
> * %rsi page_list
> @@ -223,6 +224,7 @@ SYM_CODE_END(identity_mapped)
>
> SYM_CODE_START_LOCAL_NOALIGN(virtual_mapped)
> UNWIND_HINT_EMPTY
> + ANNOTATE_NOENDBR // RET target, above
> movq RSP(%r8), %rsp
> movq CR4(%r8), %rax
> movq %rax, %cr4
> --- a/arch/x86/lib/error-inject.c
> +++ b/arch/x86/lib/error-inject.c
> @@ -3,6 +3,7 @@
> #include <linux/linkage.h>
> #include <linux/error-injection.h>
> #include <linux/kprobes.h>
> +#include <linux/objtool.h>
>
> asmlinkage void just_return_func(void);
>
> @@ -11,6 +12,7 @@ asm(
> ".type just_return_func, @function\n"
> ".globl just_return_func\n"
> "just_return_func:\n"
> + ANNOTATE_NOENDBR
> ASM_RET
> ".size just_return_func, .-just_return_func\n"
> );
> --- a/arch/x86/lib/retpoline.S
> +++ b/arch/x86/lib/retpoline.S
> @@ -55,6 +55,7 @@ SYM_INNER_LABEL(__x86_indirect_thunk_\re
>
> .align RETPOLINE_THUNK_SIZE
> SYM_CODE_START(__x86_indirect_thunk_array)
> + ANNOTATE_NOENDBR // apply_retpolines
>
> #define GEN(reg) THUNK reg
> #include <asm/GEN-for-each-reg.h>
>
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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