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authorAriel Marcovitch <arielmarcovitch@gmail.com>2021-01-02 22:11:56 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2021-01-12 15:06:23 +1100
commit2225a8dda263edc35a0e8b858fe2945cf6240fde (patch)
treee2964aa26736f785fdea48287a2567c19c704bbb /arch
parent3ce47d95b7346dcafd9bed3556a8d072cb2b8571 (diff)
powerpc: Fix alignment bug within the init sections
This is a bug that causes early crashes in builds with an .exit.text section smaller than a page and an .init.text section that ends in the beginning of a physical page (this is kinda random, which might explain why this wasn't really encountered before). The init sections are ordered like this: .init.text .exit.text .init.data Currently, these sections aren't page aligned. Because the init code might become read-only at runtime and because the .init.text section can potentially reside on the same physical page as .init.data, the beginning of .init.data might be mapped read-only along with .init.text. Then when the kernel tries to modify a variable in .init.data (like kthreadd_done, used in kernel_init()) the kernel panics. To avoid this, make _einittext page aligned and also align .exit.text to make sure .init.data is always seperated from the text segments. Fixes: 060ef9d89d18 ("powerpc32: PAGE_EXEC required for inittext") Signed-off-by: Ariel Marcovitch <ariel.marcovitch@gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210102201156.10805-1-ariel.marcovitch@gmail.com
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/vmlinux.lds.S8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 8e0b1298bf19..4ab426b8b0e0 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -187,6 +187,12 @@ SECTIONS
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
_sinittext = .;
INIT_TEXT
+
+ /*
+ *.init.text might be RO so we must ensure this section ends on
+ * a page boundary.
+ */
+ . = ALIGN(PAGE_SIZE);
_einittext = .;
#ifdef CONFIG_PPC64
*(.tramp.ftrace.init);
@@ -200,6 +206,8 @@ SECTIONS
EXIT_TEXT
}
+ . = ALIGN(PAGE_SIZE);
+
INIT_DATA_SECTION(16)
. = ALIGN(8);