[PATCH v2 1/7] powerpc: move __end_rodata to cover arch read-only sections

[Nicholas Piggin]

powerpc has a number of read-only sections and tables that are put after
RO_DATA(). Move the __end_rodata symbol to cover these as well.

Setting memory to read-only at boot is done using __init_begin, change
that that to use __end_rodata. This removes the requirement for the init
section to follow read-only data.

This makes is_kernel_rodata() exactly cover the read-only region, as
well as other things using __end_rodata (e.g., kernel/dma/debug.c).
Boot dmesg also prints the rodata size more accurately.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/kernel/vmlinux.lds.S        | 3 +++
 arch/powerpc/mm/book3s32/mmu.c           | 2 +-
 arch/powerpc/mm/book3s64/hash_pgtable.c  | 2 +-
 arch/powerpc/mm/book3s64/radix_pgtable.c | 6 +++---
 arch/powerpc/mm/pgtable_32.c             | 7 ++++---
 5 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index fe22d940412f..d81e4392da26 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -210,6 +210,9 @@ SECTIONS
 	}
 #endif
 
+	. = ALIGN(STRICT_ALIGN_SIZE);
+	__end_rodata = .;
+
 /*
  * Init sections discarded at runtime
  */
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index a96b73006dfb..e13b883e4e5b 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -240,7 +240,7 @@ void mmu_mark_rodata_ro(void)
 	for (i = 0; i < nb; i++) {
 		struct ppc_bat *bat = BATS[i];
 
-		if (bat_addrs[i].start < (unsigned long)__init_begin)
+		if (bat_addrs[i].start < (unsigned long)__end_rodata)
 			bat[1].batl = (bat[1].batl & ~BPP_RW) | BPP_RX;
 	}
 
diff --git a/arch/powerpc/mm/book3s64/hash_pgtable.c b/arch/powerpc/mm/book3s64/hash_pgtable.c
index ae008b9df0e6..28332001bd87 100644
--- a/arch/powerpc/mm/book3s64/hash_pgtable.c
+++ b/arch/powerpc/mm/book3s64/hash_pgtable.c
@@ -541,7 +541,7 @@ void hash__mark_rodata_ro(void)
 	unsigned long start, end, pp;
 
 	start = (unsigned long)_stext;
-	end = (unsigned long)__init_begin;
+	end = (unsigned long)__end_rodata;
 
 	pp = htab_convert_pte_flags(pgprot_val(PAGE_KERNEL_ROX), HPTE_USE_KERNEL_KEY);
 
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 698274109c91..eb3c56975c37 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -228,7 +228,7 @@ void radix__mark_rodata_ro(void)
 	unsigned long start, end;
 
 	start = (unsigned long)_stext;
-	end = (unsigned long)__init_begin;
+	end = (unsigned long)__end_rodata;
 
 	radix__change_memory_range(start, end, _PAGE_WRITE);
 }
@@ -259,8 +259,8 @@ print_mapping(unsigned long start, unsigned long end, unsigned long size, bool e
 static unsigned long next_boundary(unsigned long addr, unsigned long end)
 {
 #ifdef CONFIG_STRICT_KERNEL_RWX
-	if (addr < __pa_symbol(__init_begin))
-		return __pa_symbol(__init_begin);
+	if (addr < __pa_symbol(__end_rodata))
+		return __pa_symbol(__end_rodata);
 #endif
 	return end;
 }
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 3ac73f9fb5d5..5c02fd08d61e 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -158,10 +158,11 @@ void mark_rodata_ro(void)
 	}
 
 	/*
-	 * mark .text and .rodata as read only. Use __init_begin rather than
-	 * __end_rodata to cover NOTES and EXCEPTION_TABLE.
+	 * mark text and rodata as read only. __end_rodata is set by
+	 * powerpc's linker script and includes tables and data
+	 * requiring relocation which are not put in RO_DATA.
 	 */
-	numpages = PFN_UP((unsigned long)__init_begin) -
+	numpages = PFN_UP((unsigned long)__end_rodata) -
 		   PFN_DOWN((unsigned long)_stext);
 
 	set_memory_ro((unsigned long)_stext, numpages);
-- 
2.37.2