From: Thomas Garnier <thgarnie@chromium.org>
To: kernel-hardening@lists.openwall.com
Cc: kristen@linux.intel.com, keescook@chromium.org,
Thomas Garnier <thgarnie@chromium.org>,
Juergen Gross <jgross@suse.com>,
Thomas Hellstrom <thellstrom@vmware.com>,
"VMware, Inc." <pv-drivers@vmware.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v10 10/11] x86/paravirt: Adapt assembly for PIE support
Date: Wed, 4 Dec 2019 16:09:47 -0800 [thread overview]
Message-ID: <20191205000957.112719-11-thgarnie@chromium.org> (raw)
In-Reply-To: <20191205000957.112719-1-thgarnie@chromium.org>
If PIE is enabled, switch the paravirt assembly constraints to be
compatible. The %c/i constrains generate smaller code so is kept by
default.
Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.
Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
Acked-by: Juergen Gross <jgross@suse.com>
---
arch/x86/include/asm/paravirt_types.h | 32 +++++++++++++++++++++++----
1 file changed, 28 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 84812964d3dd..82f7ca22e0ae 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -336,9 +336,32 @@ extern struct paravirt_patch_template pv_ops;
#define PARAVIRT_PATCH(x) \
(offsetof(struct paravirt_patch_template, x) / sizeof(void *))
+#ifdef CONFIG_X86_PIE
+#define paravirt_opptr_call "a"
+#define paravirt_opptr_type "p"
+
+/*
+ * Alternative patching requires a maximum of 7 bytes but the relative call is
+ * only 6 bytes. If PIE is enabled, add an additional nop to the call
+ * instruction to ensure patching is possible.
+ *
+ * Without PIE, the call is reg/mem64:
+ * ff 14 25 68 37 02 82 callq *0xffffffff82023768
+ *
+ * With PIE, it is relative to %rip and take 1-less byte:
+ * ff 15 fa d9 ff 00 callq *0xffd9fa(%rip) # <pv_ops+0x30>
+ *
+ */
+#define PARAVIRT_CALL_POST "nop;"
+#else
+#define paravirt_opptr_call "c"
+#define paravirt_opptr_type "i"
+#define PARAVIRT_CALL_POST ""
+#endif
+
#define paravirt_type(op) \
[paravirt_typenum] "i" (PARAVIRT_PATCH(op)), \
- [paravirt_opptr] "i" (&(pv_ops.op))
+ [paravirt_opptr] paravirt_opptr_type (&(pv_ops.op))
#define paravirt_clobber(clobber) \
[paravirt_clobber] "i" (clobber)
@@ -377,9 +400,10 @@ int paravirt_disable_iospace(void);
* offset into the paravirt_patch_template structure, and can therefore be
* freely converted back into a structure offset.
*/
-#define PARAVIRT_CALL \
- ANNOTATE_RETPOLINE_SAFE \
- "call *%c[paravirt_opptr];"
+#define PARAVIRT_CALL \
+ ANNOTATE_RETPOLINE_SAFE \
+ "call *%" paravirt_opptr_call "[paravirt_opptr];" \
+ PARAVIRT_CALL_POST
/*
* These macros are intended to wrap calls through one of the paravirt
--
2.24.0.393.g34dc348eaf-goog
next prev parent reply other threads:[~2019-12-05 0:12 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 0:09 [PATCH v10 00/11] x86: PIE support to extend KASLR randomization Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 01/11] x86/crypto: Adapt assembly for PIE support Thomas Garnier
2019-12-18 12:46 ` Borislav Petkov
2019-12-18 16:35 ` Thomas Garnier
2019-12-18 16:45 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 02/11] x86: Add macro to get symbol address " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 03/11] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 04/11] x86/entry/64: " Thomas Garnier
2019-12-05 9:03 ` Peter Zijlstra
2019-12-05 17:01 ` Thomas Garnier
2019-12-06 10:26 ` Peter Zijlstra
2019-12-06 16:35 ` Thomas Garnier
2019-12-20 16:05 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 05/11] x86: pm-trace - " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 06/11] x86/CPU: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 07/11] x86/acpi: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 08/11] x86/boot/64: " Thomas Garnier
2019-12-05 0:09 ` [PATCH v10 09/11] x86/power/64: " Thomas Garnier
2019-12-05 0:09 ` Thomas Garnier [this message]
2019-12-23 17:23 ` [PATCH v10 10/11] x86/paravirt: " Borislav Petkov
2019-12-24 10:04 ` Borislav Petkov
2019-12-05 0:09 ` [PATCH v10 11/11] x86/alternatives: " Thomas Garnier
2019-12-19 13:34 ` [PATCH v10 00/11] x86: PIE support to extend KASLR randomization Peter Zijlstra
2019-12-19 16:35 ` Thomas Garnier
2019-12-24 13:03 ` Borislav Petkov
2019-12-30 18:52 ` Kees Cook
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