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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Nicolas Pitre <nico@fluxnic.net>,
	Linus Walleij <linus.walleij@linaro.org>,
	Russell King <linux@armlinux.org.uk>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>
Subject: [PATCH v4 4/5] ARM: decompressor: move GOT into .data for EFI enabled builds
Date: Tue, 19 May 2020 18:26:44 +0200	[thread overview]
Message-ID: <20200519162645.31065-5-ardb@kernel.org> (raw)
In-Reply-To: <20200519162645.31065-1-ardb@kernel.org>

We will be running the decompressor in place after a future patch,
instead of copying it around first. This means we no longer have to
disable and re-enable the MMU and caches either. However, this means
we will be loaded with the restricted permissions set by the UEFI
firmware, which means that we have to move the GOT table into the
data section in order for the contents to be writable by the code
itself.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
---
 arch/arm/boot/compressed/vmlinux.lds.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
index b247f399de71..d0619ec05705 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.S
+++ b/arch/arm/boot/compressed/vmlinux.lds.S
@@ -63,9 +63,11 @@ SECTIONS
   _etext = .;
 
   .got.plt		: { *(.got.plt) }
+#ifndef CONFIG_EFI_STUB
   _got_start = .;
   .got			: { *(.got) }
   _got_end = .;
+#endif
 
   /* ensure the zImage file size is always a multiple of 64 bits */
   /* (without a dummy byte, ld just ignores the empty section) */
@@ -74,6 +76,9 @@ SECTIONS
 #ifdef CONFIG_EFI_STUB
   .data : ALIGN(4096) {
     __pecoff_data_start = .;
+    _got_start = .;
+    *(.got)
+    _got_end = .;
     /*
      * The EFI stub always executes from RAM, and runs strictly before the
      * decompressor, so we can make an exception for its r/w data, and keep it
-- 
2.17.1


WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-efi@vger.kernel.org,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Nicolas Pitre <nico@fluxnic.net>,
	Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Linus Walleij <linus.walleij@linaro.org>,
	Russell King <linux@armlinux.org.uk>,
	Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH v4 4/5] ARM: decompressor: move GOT into .data for EFI enabled builds
Date: Tue, 19 May 2020 18:26:44 +0200	[thread overview]
Message-ID: <20200519162645.31065-5-ardb@kernel.org> (raw)
In-Reply-To: <20200519162645.31065-1-ardb@kernel.org>

We will be running the decompressor in place after a future patch,
instead of copying it around first. This means we no longer have to
disable and re-enable the MMU and caches either. However, this means
we will be loaded with the restricted permissions set by the UEFI
firmware, which means that we have to move the GOT table into the
data section in order for the contents to be writable by the code
itself.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
---
 arch/arm/boot/compressed/vmlinux.lds.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/boot/compressed/vmlinux.lds.S b/arch/arm/boot/compressed/vmlinux.lds.S
index b247f399de71..d0619ec05705 100644
--- a/arch/arm/boot/compressed/vmlinux.lds.S
+++ b/arch/arm/boot/compressed/vmlinux.lds.S
@@ -63,9 +63,11 @@ SECTIONS
   _etext = .;
 
   .got.plt		: { *(.got.plt) }
+#ifndef CONFIG_EFI_STUB
   _got_start = .;
   .got			: { *(.got) }
   _got_end = .;
+#endif
 
   /* ensure the zImage file size is always a multiple of 64 bits */
   /* (without a dummy byte, ld just ignores the empty section) */
@@ -74,6 +76,9 @@ SECTIONS
 #ifdef CONFIG_EFI_STUB
   .data : ALIGN(4096) {
     __pecoff_data_start = .;
+    _got_start = .;
+    *(.got)
+    _got_end = .;
     /*
      * The EFI stub always executes from RAM, and runs strictly before the
      * decompressor, so we can make an exception for its r/w data, and keep it
-- 
2.17.1


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  parent reply	other threads:[~2020-05-19 16:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-19 16:26 [PATCH v4 0/5] ARM: simplify handover from UEFI to decompressor Ard Biesheuvel
2020-05-19 16:26 ` Ard Biesheuvel
2020-05-19 16:26 ` [PATCH v4 1/5] ARM: decompressor: move headroom variable out of LC0 Ard Biesheuvel
2020-05-19 16:26   ` Ard Biesheuvel
2020-05-19 16:26 ` [PATCH v4 2/5] ARM: decompressor: split off _edata and stack base into separate object Ard Biesheuvel
2020-05-19 16:26   ` Ard Biesheuvel
2020-05-19 16:26 ` [PATCH v4 3/5] ARM: decompressor: defer loading of the contents of the LC0 structure Ard Biesheuvel
2020-05-19 16:26   ` Ard Biesheuvel
2020-05-19 16:26 ` Ard Biesheuvel [this message]
2020-05-19 16:26   ` [PATCH v4 4/5] ARM: decompressor: move GOT into .data for EFI enabled builds Ard Biesheuvel
2020-05-19 16:26 ` [PATCH v4 5/5] ARM: decompressor: run decompressor in place if loaded via UEFI Ard Biesheuvel
2020-05-19 16:26   ` Ard Biesheuvel

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