linux-kernel - [PATCH] arm64: kernel: remove SHF_WRITE|SHF

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Message-ID: <20230428-awx-v1-1-1f490286ba62@google.com>
Date:   Fri, 28 Apr 2023 11:09:25 -0700
From:   ndesaulniers@...gle.com
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Fangrui Song <maskray@...gle.com>,
        Greg Thelen <gthelen@...gle.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH] arm64: kernel: remove SHF_WRITE|SHF_EXECINSTR from .idmap.text

commit d54170812ef1 ("arm64: fix .idmap.text assertion for large kernels")
modified some of the section assembler directives that declare
.idmap.text to be SHF_ALLOC instead of
SHF_ALLOC|SHF_WRITE|SHF_EXECINSTR.

This patch fixes up the remaining stragglers that were left behind.

Because .idmap.text is merged into .text, LLD will retain the
SHF_EXECINSTR on .text, in addition to the synthetic .got.  This doesn't
matter to the kernel loader, but syzkaller is having trouble symboling
such sections. Clean this up while we additionally fix up syzkaller. Add
Fixes tag so that this doesn't precede related change in stable.

Fixes: d54170812ef1 ("arm64: fix .idmap.text assertion for large kernels")
Reported-by: Greg Thelen <gthelen@...gle.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
 arch/arm64/kernel/cpu-reset.S | 2 +-
 arch/arm64/kernel/sleep.S     | 2 +-
 arch/arm64/mm/proc.S          | 6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 6b752fe89745..c87445dde674 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -14,7 +14,7 @@
 #include <asm/virt.h>
 
 .text
-.pushsection    .idmap.text, "awx"
+.pushsection    .idmap.text, "a"
 
 /*
  * cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2)
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index 2ae7cff1953a..2aa5129d8253 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -97,7 +97,7 @@ SYM_FUNC_START(__cpu_suspend_enter)
 	ret
 SYM_FUNC_END(__cpu_suspend_enter)
 
-	.pushsection ".idmap.text", "awx"
+	.pushsection ".idmap.text", "a"
 SYM_CODE_START(cpu_resume)
 	mov	x0, xzr
 	bl	init_kernel_el
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 91410f488090..c2cb437821ca 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -167,7 +167,7 @@ alternative_else_nop_endif
 SYM_FUNC_END(cpu_do_resume)
 #endif
 
-	.pushsection ".idmap.text", "awx"
+	.pushsection ".idmap.text", "a"
 
 .macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
 	adrp	\tmp1, reserved_pg_dir
@@ -201,7 +201,7 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1)
 
 #define KPTI_NG_PTE_FLAGS	(PTE_ATTRINDX(MT_NORMAL) | SWAPPER_PTE_FLAGS)
 
-	.pushsection ".idmap.text", "awx"
+	.pushsection ".idmap.text", "a"
 
 	.macro	kpti_mk_tbl_ng, type, num_entries
 	add	end_\type\()p, cur_\type\()p, #\num_entries * 8
@@ -400,7 +400,7 @@ SYM_FUNC_END(idmap_kpti_install_ng_mappings)
  * Output:
  *	Return in x0 the value of the SCTLR_EL1 register.
  */
-	.pushsection ".idmap.text", "awx"
+	.pushsection ".idmap.text", "a"
 SYM_FUNC_START(__cpu_setup)
 	tlbi	vmalle1				// Invalidate local TLB
 	dsb	nsh

---
base-commit: 22b8cc3e78f5448b4c5df00303817a9137cd663f
change-id: 20230428-awx-c73f4bde79c4

Best regards,
-- 
Nick Desaulniers <ndesaulniers@...gle.com>