Re: [PATCHv2 5/6] arm64: Use __pa_symbol for _end

From: Catalin Marinas
Date: Tue Nov 15 2016 - 13:35:22 EST

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In reply to: Laura Abbott: "Re: [PATCHv2 5/6] arm64: Use __pa_symbol for _end"
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On Mon, Nov 14, 2016 at 10:41:29AM -0800, Laura Abbott wrote:
> On 11/14/2016 10:19 AM, Catalin Marinas wrote:
> > On Thu, Nov 03, 2016 at 03:51:07PM +0000, Mark Rutland wrote:
> >> On Wed, Nov 02, 2016 at 05:56:42PM -0600, Laura Abbott wrote:
> >>> On 11/02/2016 04:52 PM, Mark Rutland wrote:
> >>>> On Wed, Nov 02, 2016 at 03:00:53PM -0600, Laura Abbott wrote:
> >>>>>
> >>>>> __pa_symbol is technically the marco that should be used for kernel
> >>>>> symbols. Switch to this as a pre-requisite for DEBUG_VIRTUAL.
> >>>>
> >>>> Nit: s/marco/macro/
> >>>>
> >>>> I see there are some other uses of __pa() that look like they could/should be
> >>>> __pa_symbol(), e.g. in mark_rodata_ro().
> >>>>
> >>>> I guess strictly speaking those need to be updated to? Or is there a reason
> >>>> that we should not?
> >>>
> >>> If the concept of __pa_symbol is okay then yes I think all uses of __pa
> >>> should eventually be converted for consistency and debugging.
> >>
> >> I have no strong feelings either way about __pa_symbol(); I'm not clear on what
> >> the purpose of __pa_symbol() is specifically, but I'm happy even if it's just
> >> for consistency with other architectures.
> >
> > At a quick grep, it seems to only be used by mips and x86 and a single
> > place in mm/memblock.c.
> >
> > Since we haven't seen any issues on arm/arm64 without this macro, can we
> > not just continue to use __pa()?
>
> Technically yes but if it's introduced it may be confusing why it's being
> used some places but not others.

As it currently stands, your patches introduce the first and only use of
__pa_symbol to arch/arm64. But I don't see the point, unless we replace
all of the other uses.

> Maybe the bounds in the debug virtual check should just be adjusted so
> we don't need __pa_symbol along with a nice fat comment explaining
> why.

I'm fine with __pa_symbol use entirely from under arch/arm64. But if you
want to use __pa_symbol, I tried to change most (all?) places where
necessary, together with making virt_to_phys() only deal with the kernel
linear mapping. Not sure it looks cleaner, especially the
__va(__pa_symbol()) cases (we could replace the latter with another
macro and proper comment):

-------------8<--------------------------------------
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index a79b969c26fc..fa6c44ebb51f 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -47,7 +47,7 @@
* If the page is in the bottom half, we have to use the top half. If
* the page is in the top half, we have to use the bottom half:
*
- * T = __virt_to_phys(__hyp_idmap_text_start)
+ * T = __pa_symbol(__hyp_idmap_text_start)
* if (T & BIT(VA_BITS - 1))
* HYP_VA_MIN = 0 //idmap in upper half
* else
@@ -271,7 +271,7 @@ static inline void __kvm_flush_dcache_pud(pud_t pud)
kvm_flush_dcache_to_poc(page_address(page), PUD_SIZE);
}

-#define kvm_virt_to_phys(x) __virt_to_phys((unsigned long)(x))
+#define kvm_virt_to_phys(x) __pa_symbol((unsigned long)(x))

void kvm_set_way_flush(struct kvm_vcpu *vcpu);
void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled);
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index eac3dbb7e313..e02f45e5ee1b 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -169,15 +169,22 @@ extern u64 kimage_voffset;
*/
#define __virt_to_phys_nodebug(x) ({ \
phys_addr_t __x = (phys_addr_t)(x); \
- __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
- (__x - kimage_voffset); })
+ VM_BUG_ON(!(__x & BIT(VA_BITS - 1))); \
+ ((__x & ~PAGE_OFFSET) + PHYS_OFFSET); \
+})
+
+#define __pa_symbol_nodebug(x) ({ \
+ phys_addr_t __x = (phys_addr_t)(x); \
+ VM_BUG_ON(__x & BIT(VA_BITS - 1)); \
+ (__x - kimage_voffset); \
+})

#ifdef CONFIG_DEBUG_VIRTUAL
extern unsigned long __virt_to_phys(unsigned long x);
extern unsigned long __phys_addr_symbol(unsigned long x);
#else
#define __virt_to_phys(x) __virt_to_phys_nodebug(x)
-#define __phys_addr_symbol __pa
+#define __phys_addr_symbol(x) __pa_symbol_nodebug(x)
#endif

#define __phys_to_virt(x) ((unsigned long)((x) - PHYS_OFFSET) | PAGE_OFFSET)
@@ -210,7 +217,7 @@ static inline void *phys_to_virt(phys_addr_t x)
* Drivers should NOT use these either.
*/
#define __pa(x) __virt_to_phys((unsigned long)(x))
-#define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
+#define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
#define __pa_nodebug(x) __virt_to_phys_nodebug((unsigned long)(x))
#define __va(x) ((void *)__phys_to_virt((phys_addr_t)(x)))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index a50185375f09..6cf3763c6e11 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -44,7 +44,7 @@ static inline void contextidr_thread_switch(struct task_struct *next)
*/
static inline void cpu_set_reserved_ttbr0(void)
{
- unsigned long ttbr = virt_to_phys(empty_zero_page);
+ unsigned long ttbr = __pa_symbol(empty_zero_page);

write_sysreg(ttbr, ttbr0_el1);
isb();
@@ -113,7 +113,7 @@ static inline void cpu_install_idmap(void)
local_flush_tlb_all();
cpu_set_idmap_tcr_t0sz();

- cpu_switch_mm(idmap_pg_dir, &init_mm);
+ cpu_switch_mm(__va(__pa_symbol(idmap_pg_dir)), &init_mm);
}

/*
@@ -128,7 +128,7 @@ static inline void cpu_replace_ttbr1(pgd_t *pgd)

phys_addr_t pgd_phys = virt_to_phys(pgd);

- replace_phys = (void *)virt_to_phys(idmap_cpu_replace_ttbr1);
+ replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);

cpu_install_idmap();
replace_phys(pgd_phys);
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index ffbb9a520563..c2041a39a3e3 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -52,7 +52,7 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
* for zero-mapped memory areas etc..
*/
extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
-#define ZERO_PAGE(vaddr) pfn_to_page(PHYS_PFN(__pa(empty_zero_page)))
+#define ZERO_PAGE(vaddr) pfn_to_page(PHYS_PFN(__pa_symbol(empty_zero_page)))

#define pte_ERROR(pte) __pte_error(__FILE__, __LINE__, pte_val(pte))

diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c
index a32b4011d711..df58310660c6 100644
--- a/arch/arm64/kernel/acpi_parking_protocol.c
+++ b/arch/arm64/kernel/acpi_parking_protocol.c
@@ -109,7 +109,7 @@ static int acpi_parking_protocol_cpu_boot(unsigned int cpu)
* that read this address need to convert this address to the
* Boot-Loader's endianness before jumping.
*/
- writeq_relaxed(__pa(secondary_entry), &mailbox->entry_point);
+ writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point);
writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id);

arch_send_wakeup_ipi_mask(cpumask_of(cpu));
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c02504ea304b..6ccadf255fba 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -736,7 +736,7 @@ static bool runs_at_el2(const struct arm64_cpu_capabilities *entry, int __unused
static bool hyp_offset_low(const struct arm64_cpu_capabilities *entry,
int __unused)
{
- phys_addr_t idmap_addr = virt_to_phys(__hyp_idmap_text_start);
+ phys_addr_t idmap_addr = __pa_symbol(__hyp_idmap_text_start);

/*
* Activate the lower HYP offset only if:
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index d55a7b09959b..81c03c74e5fe 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -51,7 +51,7 @@
extern int in_suspend;

/* Find a symbols alias in the linear map */
-#define LMADDR(x) phys_to_virt(virt_to_phys(x))
+#define LMADDR(x) __va(__pa_symbol(x))

/* Do we need to reset el2? */
#define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())
@@ -125,12 +125,12 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
return -EOVERFLOW;

arch_hdr_invariants(&hdr->invariants);
- hdr->ttbr1_el1 = virt_to_phys(swapper_pg_dir);
+ hdr->ttbr1_el1 = __pa_symbol(swapper_pg_dir);
hdr->reenter_kernel = _cpu_resume;

/* We can't use __hyp_get_vectors() because kvm may still be loaded */
if (el2_reset_needed())
- hdr->__hyp_stub_vectors = virt_to_phys(__hyp_stub_vectors);
+ hdr->__hyp_stub_vectors = __pa_symbol(__hyp_stub_vectors);
else
hdr->__hyp_stub_vectors = 0;

diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 6f2ac4fc66ca..af8967a0343b 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -97,7 +97,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
page = vmalloc_to_page(addr);
else if (!module)
- page = pfn_to_page(PHYS_PFN(__pa(addr)));
+ page = pfn_to_page(PHYS_PFN(__pa_symbol(addr)));
else
return addr;

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 42816bebb1e0..f0f2abb72cf9 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -45,7 +45,7 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu)

static int cpu_psci_cpu_boot(unsigned int cpu)
{
- int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa(secondary_entry));
+ int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
if (err)
pr_err("failed to boot CPU%d (%d)\n", cpu, err);

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index f534f492a268..e2dbc02f4792 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -199,10 +199,10 @@ static void __init request_standard_resources(void)
struct memblock_region *region;
struct resource *res;

- kernel_code.start = virt_to_phys(_text);
- kernel_code.end = virt_to_phys(__init_begin - 1);
- kernel_data.start = virt_to_phys(_sdata);
- kernel_data.end = virt_to_phys(_end - 1);
+ kernel_code.start = __pa_symbol(_text);
+ kernel_code.end = __pa_symbol(__init_begin - 1);
+ kernel_data.start = __pa_symbol(_sdata);
+ kernel_data.end = __pa_symbol(_end - 1);

for_each_memblock(memory, region) {
res = alloc_bootmem_low(sizeof(*res));
diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
index 9a00eee9acc8..25fcccaf79b8 100644
--- a/arch/arm64/kernel/smp_spin_table.c
+++ b/arch/arm64/kernel/smp_spin_table.c
@@ -98,7 +98,7 @@ static int smp_spin_table_cpu_prepare(unsigned int cpu)
* boot-loader's endianess before jumping. This is mandated by
* the boot protocol.
*/
- writeq_relaxed(__pa(secondary_holding_pen), release_addr);
+ writeq_relaxed(__pa_symbol(secondary_holding_pen), release_addr);
__flush_dcache_area((__force void *)release_addr,
sizeof(*release_addr));

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index a2c2478e7d78..791e87a99148 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -140,11 +140,11 @@ static int __init vdso_init(void)
return -ENOMEM;

/* Grab the vDSO data page. */
- vdso_pagelist[0] = pfn_to_page(PHYS_PFN(__pa(vdso_data)));
+ vdso_pagelist[0] = pfn_to_page(PHYS_PFN(__pa_symbol(vdso_data)));

/* Grab the vDSO code pages. */
for (i = 0; i < vdso_pages; i++)
- vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa(&vdso_start)) + i);
+ vdso_pagelist[i + 1] = pfn_to_page(PHYS_PFN(__pa_symbol(&vdso_start)) + i);

vdso_spec[0].pages = &vdso_pagelist[0];
vdso_spec[1].pages = &vdso_pagelist[1];
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 3236eb062444..14f426fea61b 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -225,7 +225,7 @@ void __init arm64_memblock_init(void)
*/
if (memory_limit != (phys_addr_t)ULLONG_MAX) {
memblock_mem_limit_remove_map(memory_limit);
- memblock_add(__pa(_text), (u64)(_end - _text));
+ memblock_add(__pa_symbol(_text), (u64)(_end - _text));
}

if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
@@ -278,7 +278,7 @@ void __init arm64_memblock_init(void)
* Register the kernel text, kernel data, initrd, and initial
* pagetables with memblock.
*/
- memblock_reserve(__pa(_text), _end - _text);
+ memblock_reserve(__pa_symbol(_text), _end - _text);
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start) {
memblock_reserve(initrd_start, initrd_end - initrd_start);
@@ -483,7 +483,8 @@ void __init mem_init(void)

void free_initmem(void)
{
- free_reserved_area(__va(__pa(__init_begin)), __va(__pa(__init_end)),
+ free_reserved_area(__va(__pa_symbol(__init_begin)),
+ __va(__pa_symbol(__init_end)),
0, "unused kernel");
/*
* Unmap the __init region but leave the VM area in place. This
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 17243e43184e..f7c0a47a8ebd 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -359,8 +359,8 @@ static void create_mapping_late(phys_addr_t phys, unsigned long virt,

static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end)
{
- unsigned long kernel_start = __pa(_text);
- unsigned long kernel_end = __pa(__init_begin);
+ unsigned long kernel_start = __pa_symbol(_text);
+ unsigned long kernel_end = __pa_symbol(__init_begin);

/*
* Take care not to create a writable alias for the
@@ -427,14 +427,14 @@ void mark_rodata_ro(void)
unsigned long section_size;

section_size = (unsigned long)_etext - (unsigned long)_text;
- create_mapping_late(__pa(_text), (unsigned long)_text,
+ create_mapping_late(__pa_symbol(_text), (unsigned long)_text,
section_size, PAGE_KERNEL_ROX);
/*
* mark .rodata as read only. Use __init_begin rather than __end_rodata
* to cover NOTES and EXCEPTION_TABLE.
*/
section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
- create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata,
+ create_mapping_late(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
section_size, PAGE_KERNEL_RO);

/* flush the TLBs after updating live kernel mappings */
@@ -446,7 +446,7 @@ void mark_rodata_ro(void)
static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
pgprot_t prot, struct vm_struct *vma)
{
- phys_addr_t pa_start = __pa(va_start);
+ phys_addr_t pa_start = __pa_symbol(va_start);
unsigned long size = va_end - va_start;

BUG_ON(!PAGE_ALIGNED(pa_start));
@@ -494,7 +494,7 @@ static void __init map_kernel(pgd_t *pgd)
*/
BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
set_pud(pud_set_fixmap_offset(pgd, FIXADDR_START),
- __pud(__pa(bm_pmd) | PUD_TYPE_TABLE));
+ __pud(__pa_symbol(bm_pmd) | PUD_TYPE_TABLE));
pud_clear_fixmap();
} else {
BUG();
@@ -525,7 +525,7 @@ void __init paging_init(void)
*/
cpu_replace_ttbr1(__va(pgd_phys));
memcpy(swapper_pg_dir, pgd, PAGE_SIZE);
- cpu_replace_ttbr1(swapper_pg_dir);
+ cpu_replace_ttbr1(__va(__pa_symbol(swapper_pg_dir)));

pgd_clear_fixmap();
memblock_free(pgd_phys, PAGE_SIZE);
@@ -534,7 +534,7 @@ void __init paging_init(void)
* We only reuse the PGD from the swapper_pg_dir, not the pud + pmd
* allocated with it.
*/
- memblock_free(__pa(swapper_pg_dir) + PAGE_SIZE,
+ memblock_free(__pa_symbol(swapper_pg_dir) + PAGE_SIZE,
SWAPPER_DIR_SIZE - PAGE_SIZE);
}

@@ -654,7 +654,7 @@ void __init early_fixmap_init(void)

pgd = pgd_offset_k(addr);
if (CONFIG_PGTABLE_LEVELS > 3 &&
- !(pgd_none(*pgd) || pgd_page_paddr(*pgd) == __pa(bm_pud))) {
+ !(pgd_none(*pgd) || pgd_page_paddr(*pgd) == __pa_symbol(bm_pud))) {
/*
* We only end up here if the kernel mapping and the fixmap
* share the top level pgd entry, which should only happen on
@@ -663,12 +663,12 @@ void __init early_fixmap_init(void)
BUG_ON(!IS_ENABLED(CONFIG_ARM64_16K_PAGES));
pud = pud_offset_kimg(pgd, addr);
} else {
- pgd_populate(&init_mm, pgd, bm_pud);
+ pgd_populate(&init_mm, pgd, __va(__pa_symbol(bm_pud)));
pud = fixmap_pud(addr);
}
- pud_populate(&init_mm, pud, bm_pmd);
+ pud_populate(&init_mm, pud, __va(__pa_symbol(bm_pmd)));
pmd = fixmap_pmd(addr);
- pmd_populate_kernel(&init_mm, pmd, bm_pte);
+ pmd_populate_kernel(&init_mm, pmd, __va(__pa_symbol(bm_pte)));

/*
* The boot-ioremap range spans multiple pmds, for which
diff --git a/arch/arm64/mm/physaddr.c b/arch/arm64/mm/physaddr.c
index 874c78201a2b..98dae943e496 100644
--- a/arch/arm64/mm/physaddr.c
+++ b/arch/arm64/mm/physaddr.c
@@ -14,8 +14,8 @@ unsigned long __virt_to_phys(unsigned long x)
*/
return (__x & ~PAGE_OFFSET) + PHYS_OFFSET;
} else {
- VIRTUAL_BUG_ON(x < kimage_vaddr || x >= (unsigned long)_end);
- return (__x - kimage_voffset);
+ WARN_ON(1);
+ return __phys_addr_symbol(x);
}
}
EXPORT_SYMBOL(__virt_to_phys);
diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 8263429e21b8..9defbe243c2f 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -383,7 +383,7 @@ static int psci_suspend_finisher(unsigned long index)
u32 *state = __this_cpu_read(psci_power_state);

return psci_ops.cpu_suspend(state[index - 1],
- virt_to_phys(cpu_resume));
+ __pa_symbol(cpu_resume));
}

int psci_cpu_suspend_enter(unsigned long index)

--
Catalin

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