linux-kernel - Re: [PATCH v10 33/38] x86/entry: Add fred_entry_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 21 Sep 2023 14:38:48 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Nikolay Borisov <nik.borisov@...e.com>, Xin Li <xin3.li@...el.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-edac@...r.kernel.org, linux-hyperv@...r.kernel.org,
        kvm@...r.kernel.org, xen-devel@...ts.xenproject.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        luto@...nel.org, seanjc@...gle.com, peterz@...radead.org,
        jgross@...e.com, ravi.v.shankar@...el.com, mhiramat@...nel.org,
        andrew.cooper3@...rix.com, jiangshanlai@...il.com
Subject: Re: [PATCH v10 33/38] x86/entry: Add fred_entry_from_kvm() for VMX to
 handle IRQ/NMI

On 9/21/23 14:11, Nikolay Borisov wrote:
>>
>> +SYM_FUNC_START(asm_fred_entry_from_kvm)
>> +    push %rbp
>> +    mov %rsp, %rbp
> 
> use FRAME_BEGIN/FRAME_END macros to ommit this code if 
> CONFIG_FRAME_POINTER is disabled.

No, the previous stack pointer is used below, so the code might as well 
use %rbp for that; but it must do so unconditionally.

Paolo

>> +
>> +    UNWIND_HINT_SAVE
>> +
>> +    /*
>> +     * Don't check the FRED stack level, the call stack leading to this
>> +     * helper is effectively constant and shallow (relatively speaking).
>> +     *
>> +     * Emulate the FRED-defined redzone and stack alignment.
>> +     */
>> +    sub $(FRED_CONFIG_REDZONE_AMOUNT << 6), %rsp
>> +    and $FRED_STACK_FRAME_RSP_MASK, %rsp
>> +
>> +    /*
>> +     * Start to push a FRED stack frame, which is always 64 bytes:
>> +     *
>> +     * +--------+-----------------+
>> +     * | Bytes  | Usage           |
>> +     * +--------+-----------------+
>> +     * | 63:56  | Reserved        |
>> +     * | 55:48  | Event Data      |
>> +     * | 47:40  | SS + Event Info |
>> +     * | 39:32  | RSP             |
>> +     * | 31:24  | RFLAGS          |
>> +     * | 23:16  | CS + Aux Info   |
>> +     * |  15:8  | RIP             |
>> +     * |   7:0  | Error Code      |
>> +     * +--------+-----------------+
>> +     */
>> +    push $0                /* Reserved, must be 0 */
>> +    push $0                /* Event data, 0 for IRQ/NMI */
>> +    push %rdi            /* fred_ss handed in by the caller */
>> +    push %rbp

^^ here

Paolo

>> +    pushf
>> +    mov $__KERNEL_CS, %rax
>> +    push %rax