From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v4 2/5] x86/alternative: add indirect call patching
Date: Tue, 14 Nov 2023 16:06:27 +0100 [thread overview]
Message-ID: <20231114150627.GDZVOM82VPHDlnD3lF@fat_crate.local> (raw)
In-Reply-To: <20231030142508.1407-3-jgross@suse.com>
On Mon, Oct 30, 2023 at 03:25:05PM +0100, Juergen Gross wrote:
> +#ifdef CONFIG_X86_64
> + /* ff 15 00 00 00 00 call *0x0(%rip) */
> + target = *(void **)(instr + a->instrlen + *(s32 *)(instr + 2));
> +#else
> + /* ff 15 00 00 00 00 call *0x0 */
> + target = *(void **)(*(s32 *)(instr + 2));
Yeah, let's document those a bit better. Either with comments above or
as Peter suggests:
/* Add 2 to skip opcode and ModRM byte: */
disp32 = *(s32 *)(instr + 2);
rip_rela_ptr = (void **)(instr + a->instrlen + disp32);
target = *rip_rela_ptr;
so that it is crystal clear what we're doing here.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-11-14 15:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-30 14:25 [PATCH v4 0/5] x86/paravirt: Get rid of paravirt patching Juergen Gross
2023-10-30 14:25 ` [PATCH v4 1/5] x86/paravirt: move some functions and defines to alternative Juergen Gross
2023-10-30 14:25 ` [PATCH v4 2/5] x86/alternative: add indirect call patching Juergen Gross
2023-11-14 12:37 ` Borislav Petkov
2023-11-14 12:50 ` Peter Zijlstra
2023-11-14 13:47 ` Borislav Petkov
2023-11-14 14:18 ` Peter Zijlstra
2023-11-14 14:27 ` Borislav Petkov
2023-11-14 14:35 ` Juergen Gross
2023-11-14 12:56 ` Juergen Gross
2023-11-14 15:06 ` Borislav Petkov [this message]
2023-11-14 16:16 ` Juergen Gross
2023-10-30 14:25 ` [PATCH v4 3/5] x86/paravirt: introduce ALT_NOT_XEN Juergen Gross
2023-11-14 15:09 ` Borislav Petkov
2023-11-14 16:17 ` Juergen Gross
2023-10-30 14:25 ` [PATCH v4 4/5] x86/paravirt: switch mixed paravirt/alternative calls to alternative_2 Juergen Gross
2023-11-21 18:45 ` Borislav Petkov
2023-11-29 10:08 ` Juergen Gross
2023-10-30 14:25 ` [PATCH v4 5/5] x86/paravirt: remove no longer needed paravirt patching code Juergen Gross
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