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From: "tip-bot2 for Arnd Bergmann" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Martin Sebor <msebor@gmail.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: x86/boot] x86/boot/tboot: Avoid Wstringop-overread-warning
Date: Mon, 22 Mar 2021 23:30:24 -0000	[thread overview]
Message-ID: <161645582418.398.5061276980736897038.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210322160253.4032422-3-arnd@kernel.org>

The following commit has been merged into the x86/boot branch of tip:

Commit-ID:     cdc34cb8f25d3125d30868376b8eae6fe690119b
Gitweb:        https://git.kernel.org/tip/cdc34cb8f25d3125d30868376b8eae6fe690119b
Author:        Arnd Bergmann <arnd@arndb.de>
AuthorDate:    Mon, 22 Mar 2021 17:02:40 +01:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 23 Mar 2021 00:16:13 +01:00

x86/boot/tboot: Avoid Wstringop-overread-warning

gcc-11 warns about using string operations on pointers that are
defined at compile time as offsets from a NULL pointer. Unfortunately
that also happens on the result of fix_to_virt(), which is a
compile-time constant for a constant input:

  arch/x86/kernel/tboot.c: In function 'tboot_probe':
  arch/x86/kernel/tboot.c:70:13: error: '__builtin_memcmp_eq' specified bound 16 exceeds source size 0 [-Werror=stringop-overread]
     70 |         if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
        |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I hope this can get addressed in gcc-11 before the release.

As a workaround, split up the tboot_probe() function in two halves
to separate the pointer generation from the usage. This is a bit
ugly, and hopefully gcc understands that the code is actually correct
before it learns to peek into the noinline function.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Sebor <msebor@gmail.com>
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
Link: https://lore.kernel.org/r/20210322160253.4032422-3-arnd@kernel.org
---
 arch/x86/kernel/tboot.c | 44 +++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index 4c09ba1..f9af561 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -49,6 +49,30 @@ bool tboot_enabled(void)
 	return tboot != NULL;
 }
 
+/* noinline to prevent gcc from warning about dereferencing constant fixaddr */
+static noinline __init bool check_tboot_version(void)
+{
+	if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
+		pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr);
+		return false;
+	}
+
+	if (tboot->version < 5) {
+		pr_warn("tboot version is invalid: %u\n", tboot->version);
+		return false;
+	}
+
+	pr_info("found shared page at phys addr 0x%llx:\n",
+		boot_params.tboot_addr);
+	pr_debug("version: %d\n", tboot->version);
+	pr_debug("log_addr: 0x%08x\n", tboot->log_addr);
+	pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry);
+	pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base);
+	pr_debug("tboot_size: 0x%x\n", tboot->tboot_size);
+
+	return true;
+}
+
 void __init tboot_probe(void)
 {
 	/* Look for valid page-aligned address for shared page. */
@@ -66,25 +90,9 @@ void __init tboot_probe(void)
 
 	/* Map and check for tboot UUID. */
 	set_fixmap(FIX_TBOOT_BASE, boot_params.tboot_addr);
-	tboot = (struct tboot *)fix_to_virt(FIX_TBOOT_BASE);
-	if (memcmp(&tboot_uuid, &tboot->uuid, sizeof(tboot->uuid))) {
-		pr_warn("tboot at 0x%llx is invalid\n", boot_params.tboot_addr);
+	tboot = (void *)fix_to_virt(FIX_TBOOT_BASE);
+	if (!check_tboot_version())
 		tboot = NULL;
-		return;
-	}
-	if (tboot->version < 5) {
-		pr_warn("tboot version is invalid: %u\n", tboot->version);
-		tboot = NULL;
-		return;
-	}
-
-	pr_info("found shared page at phys addr 0x%llx:\n",
-		boot_params.tboot_addr);
-	pr_debug("version: %d\n", tboot->version);
-	pr_debug("log_addr: 0x%08x\n", tboot->log_addr);
-	pr_debug("shutdown_entry: 0x%x\n", tboot->shutdown_entry);
-	pr_debug("tboot_base: 0x%08x\n", tboot->tboot_base);
-	pr_debug("tboot_size: 0x%x\n", tboot->tboot_size);
 }
 
 static pgd_t *tboot_pg_dir;

  parent reply	other threads:[~2021-03-22 23:31 UTC|newest]

Thread overview: 197+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-22 16:02 [PATCH 00/11] treewide: address gcc-11 -Wstringop-overread warnings Arnd Bergmann
2021-03-22 16:02 ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02 ` Arnd Bergmann
2021-03-22 16:02 ` Arnd Bergmann
2021-03-22 16:02 ` Arnd Bergmann
2021-03-22 16:02 ` [PATCH 01/11] x86: compressed: avoid gcc-11 -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 23:30   ` [tip: x86/boot] x86/boot/compressed: Avoid " tip-bot2 for Arnd Bergmann
2021-03-22 16:02 ` [PATCH 02/11] x86: tboot: avoid Wstringop-overread-warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 20:29   ` Ingo Molnar
2021-03-22 20:29     ` Ingo Molnar
2021-03-22 20:29     ` [Intel-gfx] " Ingo Molnar
2021-03-22 20:29     ` Ingo Molnar
2021-03-22 20:29     ` Ingo Molnar
2021-03-22 20:29     ` Ingo Molnar
2021-03-22 21:39     ` Arnd Bergmann
2021-03-22 21:39       ` Arnd Bergmann
2021-03-22 21:39       ` [Intel-gfx] " Arnd Bergmann
2021-03-22 21:39       ` Arnd Bergmann
2021-03-22 21:39       ` Arnd Bergmann
2021-03-22 21:39       ` Arnd Bergmann
2021-03-22 22:07     ` Martin Sebor
2021-03-22 22:07       ` Martin Sebor
2021-03-22 22:07       ` [Intel-gfx] " Martin Sebor
2021-03-22 22:07       ` Martin Sebor
2021-03-22 22:07       ` Martin Sebor
2021-03-22 22:07       ` Martin Sebor
2021-03-22 22:49       ` Arnd Bergmann
2021-03-22 22:49         ` Arnd Bergmann
2021-03-22 22:49         ` [Intel-gfx] " Arnd Bergmann
2021-03-22 22:49         ` Arnd Bergmann
2021-03-22 22:49         ` Arnd Bergmann
2021-03-22 22:49         ` Arnd Bergmann
2021-03-22 23:13       ` Ingo Molnar
2021-03-22 23:13         ` Ingo Molnar
2021-03-22 23:13         ` [Intel-gfx] " Ingo Molnar
2021-03-22 23:13         ` Ingo Molnar
2021-03-22 23:13         ` Ingo Molnar
2021-03-22 23:13         ` Ingo Molnar
2021-03-24  9:11       ` David Laight
2021-03-24  9:11         ` David Laight
2021-03-24  9:11         ` [Intel-gfx] " David Laight
2021-03-24  9:11         ` David Laight
2021-03-24  9:11         ` David Laight
2021-03-24  9:11         ` David Laight
2021-03-24 10:39         ` David Laight
2021-03-24 10:39           ` David Laight
2021-03-24 10:39           ` [Intel-gfx] " David Laight
2021-03-24 10:39           ` David Laight
2021-03-24 10:39           ` David Laight
2021-03-24 10:39           ` David Laight
2021-03-22 23:30   ` tip-bot2 for Arnd Bergmann [this message]
2021-03-22 16:02 ` [PATCH 03/11] security: commoncap: fix -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:31   ` Christian Brauner
2021-03-22 16:31     ` Christian Brauner
2021-03-22 16:31     ` [Intel-gfx] " Christian Brauner
2021-03-22 16:31     ` Christian Brauner
2021-03-22 16:31     ` Christian Brauner
2021-03-22 16:31     ` Christian Brauner
2021-03-24 20:50   ` James Morris
2021-03-24 20:50     ` James Morris
2021-03-24 20:50     ` [Intel-gfx] " James Morris
2021-03-24 20:50     ` James Morris
2021-03-24 20:50     ` James Morris
2021-03-24 20:50     ` James Morris
2021-03-22 16:02 ` [PATCH 04/11] ath11: Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-09-28  9:04   ` Kalle Valo
2021-09-28  9:04   ` Kalle Valo
2021-09-28  9:04     ` Kalle Valo
2021-09-28  9:04   ` Kalle Valo
2021-09-28  9:04     ` Kalle Valo
2021-09-28  9:04     ` [Intel-gfx] " Kalle Valo
2021-03-22 16:02 ` [PATCH 05/11] qnx: avoid -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02 ` [PATCH 06/11] cgroup: fix -Wzero-length-bounds warnings Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-30  8:41   ` Michal Koutný
2021-03-30  8:41     ` Michal Koutný
2021-03-30  8:41     ` [Intel-gfx] " Michal Koutný
2021-03-30  8:41     ` Michal Koutný
2021-03-30  8:41     ` Michal Koutný
2021-03-30  8:41     ` Michal Koutný
2021-03-30  9:00     ` Arnd Bergmann
2021-03-30  9:00       ` Arnd Bergmann
2021-03-30  9:00       ` [Intel-gfx] " Arnd Bergmann
2021-03-30  9:00       ` Arnd Bergmann
2021-03-30  9:00       ` Arnd Bergmann
2021-03-30  9:00       ` Arnd Bergmann
2021-03-30 14:44       ` Michal Koutný
2021-03-30 14:44         ` Michal Koutný
2021-03-30 14:44         ` [Intel-gfx] " Michal Koutný
2021-03-30 14:44         ` Michal Koutný
2021-03-30 14:44         ` Michal Koutný
2021-03-30 14:44         ` Michal Koutný
2021-03-22 16:02 ` [PATCH 07/11] ARM: sharpsl_param: work around -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02 ` [PATCH 08/11] atmel: avoid gcc -Wstringop-overflow warning Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02 ` [PATCH 09/11] scsi: lpfc: fix gcc -Wstringop-overread warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02 ` [PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-24 15:30   ` Jani Nikula
2021-03-24 15:30     ` Jani Nikula
2021-03-24 15:30     ` [Intel-gfx] " Jani Nikula
2021-03-24 15:30     ` Jani Nikula
2021-03-24 15:30     ` Jani Nikula
2021-03-24 15:30     ` Jani Nikula
2021-03-24 17:22     ` Ville Syrjälä
2021-03-24 17:22       ` Ville Syrjälä
2021-03-24 17:22       ` [Intel-gfx] " Ville Syrjälä
2021-03-24 17:22       ` Ville Syrjälä
2021-03-24 17:22       ` Ville Syrjälä
2021-03-24 17:22       ` Ville Syrjälä
2021-03-22 16:02 ` [PATCH 11/11] [RFC] drm/i915/dp: fix array overflow warning Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` [Intel-gfx] " Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-22 16:02   ` Arnd Bergmann
2021-03-25  8:05   ` Jani Nikula
2021-03-25  8:05     ` Jani Nikula
2021-03-25  8:05     ` [Intel-gfx] " Jani Nikula
2021-03-25  8:05     ` Jani Nikula
2021-03-25  8:05     ` Jani Nikula
2021-03-25  8:05     ` Jani Nikula
2021-03-25  9:53     ` Arnd Bergmann
2021-03-25  9:53       ` Arnd Bergmann
2021-03-25  9:53       ` [Intel-gfx] " Arnd Bergmann
2021-03-25  9:53       ` Arnd Bergmann
2021-03-25  9:53       ` Arnd Bergmann
2021-03-25  9:53       ` Arnd Bergmann
2021-03-25 14:49       ` Martin Sebor
2021-03-25 14:49         ` Martin Sebor
2021-03-25 14:49         ` [Intel-gfx] " Martin Sebor
2021-03-25 14:49         ` Martin Sebor
2021-03-25 14:49         ` Martin Sebor
2021-03-25 14:49         ` Martin Sebor
2021-03-30 10:56   ` Hans de Goede
2021-03-30 10:56     ` Hans de Goede
2021-03-30 10:56     ` [Intel-gfx] " Hans de Goede
2021-03-30 10:56     ` Hans de Goede
2021-03-30 10:56     ` Hans de Goede
2021-03-30 10:56     ` Hans de Goede
2021-03-22 19:10 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for treewide: address gcc-11 -Wstringop-overread warnings Patchwork
2021-03-22 19:12 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2021-03-22 19:38 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2021-03-23 15:30 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for treewide: address gcc-11 -Wstringop-overread warnings (rev2) Patchwork
2021-03-25 22:35 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for treewide: address gcc-11 -Wstringop-overread warnings (rev3) Patchwork
2021-03-30 11:50 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for treewide: address gcc-11 -Wstringop-overread warnings (rev4) Patchwork
2021-04-06  4:53 ` [PATCH 00/11] treewide: address gcc-11 -Wstringop-overread warnings Martin K. Petersen
2021-04-06  4:53   ` [Intel-gfx] " Martin K. Petersen
2021-04-06  4:53   ` Martin K. Petersen
2021-04-06  4:53   ` Martin K. Petersen
2021-04-06  4:53   ` Martin K. Petersen

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