Re: [PATCH 5/8] x86, brk: Make extend_brk() available with va/pa.

[Konrad Rzeszutek Wilk]

Tang Chen <tangchen@xxxxxxxxxxxxxx> wrote:
>We are going to do acpi_initrd_override() at very early time:
>
>On 32bit: do it in head_32.S, before paging is enabled. In this case,
>we can
>          access initrd with physical address without page tables.
>
>On 64bit: do it in head_64.c, after paging is enabled but before direct
>mapping
>          is setup.
>
>   On 64bit, we have an early page fault handler to help to access data
>     with direct mapping page tables. So it is easy to do in head_64.c.
>
>And we need to allocate memory to store override tables. At such an
>early time,
>no memory allocator works. So we can only use BRK.
>
>As mentioned above, on 32bit before paging is enabled, we have to
>access variables
>with pa. So introduce a "bool is_phys" parameter to extend_brk(), and
>convert va
>to pa is it is true.

Could you do it differently? Meaning have a global symbol (paging_enabled) which will be used by most of the functions you changed in this patch and the next ones? It would naturally be enabled when paging is on and __va addresses can be used. 

That could also be used in the printk case to do a BUG_ON before paging is enabled on 32bit. Or perhaps use a different code path to deal with using __pa address. 

? 
>
>Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
>---
> arch/x86/include/asm/dmi.h   |    2 +-
> arch/x86/include/asm/setup.h |    2 +-
> arch/x86/kernel/setup.c      |   20 ++++++++++++++------
> arch/x86/mm/init.c           |    2 +-
> arch/x86/xen/enlighten.c     |    2 +-
> arch/x86/xen/mmu.c           |    6 +++---
> arch/x86/xen/p2m.c           |   27 ++++++++++++++-------------
> drivers/acpi/osl.c           |    2 +-
> 8 files changed, 36 insertions(+), 27 deletions(-)
>
>diff --git a/arch/x86/include/asm/dmi.h b/arch/x86/include/asm/dmi.h
>index fd8f9e2..3b51d81 100644
>--- a/arch/x86/include/asm/dmi.h
>+++ b/arch/x86/include/asm/dmi.h
>@@ -9,7 +9,7 @@
> 
> static __always_inline __init void *dmi_alloc(unsigned len)
> {
>-	return extend_brk(len, sizeof(int));
>+	return extend_brk(len, sizeof(int), false);
> }
> 
> /* Use early IO mappings for DMI because it's initialized early */
>diff --git a/arch/x86/include/asm/setup.h
>b/arch/x86/include/asm/setup.h
>index 4f71d48..96d00da 100644
>--- a/arch/x86/include/asm/setup.h
>+++ b/arch/x86/include/asm/setup.h
>@@ -75,7 +75,7 @@ extern struct boot_params boot_params;
> 
> /* exceedingly early brk-like allocator */
> extern unsigned long _brk_end;
>-void *extend_brk(size_t size, size_t align);
>+void *extend_brk(size_t size, size_t align, bool is_phys);
> 
> /*
>  * Reserve space in the brk section.  The name must be unique within
>diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>index 51fcd5d..a189909 100644
>--- a/arch/x86/kernel/setup.c
>+++ b/arch/x86/kernel/setup.c
>@@ -259,19 +259,27 @@ static inline void __init copy_edd(void)
> }
> #endif
> 
>-void * __init extend_brk(size_t size, size_t align)
>+void * __init extend_brk(size_t size, size_t align, bool is_phys)
> {
> 	size_t mask = align - 1;
> 	void *ret;
>+	unsigned long *brk_start, *brk_end, *brk_limit;
> 
>-	BUG_ON(_brk_start == 0);
>+	brk_start = is_phys ? (unsigned long *)__pa_nodebug(&_brk_start) :
>+			      (unsigned long *)&_brk_start;
>+	brk_end = is_phys ? (unsigned long *)__pa_nodebug(&_brk_end) :
>+			    (unsigned long *)&_brk_end;
>+	brk_limit = is_phys ? (unsigned long *)__pa_nodebug(__brk_limit) :
>+			      (unsigned long *)__brk_limit;
>+
>+	BUG_ON(*brk_start == 0);
> 	BUG_ON(align & mask);
> 
>-	_brk_end = (_brk_end + mask) & ~mask;
>-	BUG_ON((char *)(_brk_end + size) > __brk_limit);
>+	*brk_end = (*brk_end + mask) & ~mask;
>+	BUG_ON((char *)(*brk_end + size) > brk_limit);
> 
>-	ret = (void *)_brk_end;
>-	_brk_end += size;
>+	ret = (void *)(*brk_end);
>+	*brk_end += size;
> 
> 	memset(ret, 0, size);
> 
>diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
>index 2ec29ac..189a9e2 100644
>--- a/arch/x86/mm/init.c
>+++ b/arch/x86/mm/init.c
>@@ -86,7 +86,7 @@ void  __init early_alloc_pgt_buf(void)
> 	unsigned long tables = INIT_PGT_BUF_SIZE;
> 	phys_addr_t base;
> 
>-	base = __pa(extend_brk(tables, PAGE_SIZE));
>+	base = __pa(extend_brk(tables, PAGE_SIZE, false));
> 
> 	pgt_buf_start = base >> PAGE_SHIFT;
> 	pgt_buf_end = pgt_buf_start;
>diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
>index 193097e..2d5a34f 100644
>--- a/arch/x86/xen/enlighten.c
>+++ b/arch/x86/xen/enlighten.c
>@@ -1629,7 +1629,7 @@ void __ref xen_hvm_init_shared_info(void)
> 
> 	if (!shared_info_page)
> 		shared_info_page = (struct shared_info *)
>-			extend_brk(PAGE_SIZE, PAGE_SIZE);
>+			extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 	xatp.domid = DOMID_SELF;
> 	xatp.idx = 0;
> 	xatp.space = XENMAPSPACE_shared_info;
>diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
>index fdc3ba2..573bc50 100644
>--- a/arch/x86/xen/mmu.c
>+++ b/arch/x86/xen/mmu.c
>@@ -1768,7 +1768,7 @@ static void __init xen_map_identity_early(pmd_t
>*pmd, unsigned long max_pfn)
> 	unsigned long pfn;
> 
> 	level1_ident_pgt = extend_brk(sizeof(pte_t) * LEVEL1_IDENT_ENTRIES,
>-				      PAGE_SIZE);
>+				      PAGE_SIZE, false);
> 
> 	ident_pte = 0;
> 	pfn = 0;
>@@ -1980,7 +1980,7 @@ static void __init xen_write_cr3_init(unsigned
>long cr3)
> 	 * swapper_pg_dir.
> 	 */
> 	swapper_kernel_pmd =
>-		extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
>+		extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE, false);
> 	copy_page(swapper_kernel_pmd, initial_kernel_pmd);
> 	swapper_pg_dir[KERNEL_PGD_BOUNDARY] =
> 		__pgd(__pa(swapper_kernel_pmd) | _PAGE_PRESENT);
>@@ -2003,7 +2003,7 @@ void __init xen_setup_kernel_pagetable(pgd_t
>*pgd, unsigned long max_pfn)
> 	pmd_t *kernel_pmd;
> 
> 	initial_kernel_pmd =
>-		extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE);
>+		extend_brk(sizeof(pmd_t) * PTRS_PER_PMD, PAGE_SIZE, false);
> 
> 	max_pfn_mapped = PFN_DOWN(__pa(xen_start_info->pt_base) +
> 				  xen_start_info->nr_pt_frames * PAGE_SIZE +
>diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
>index 95fb2aa..bbdcf20 100644
>--- a/arch/x86/xen/p2m.c
>+++ b/arch/x86/xen/p2m.c
>@@ -281,13 +281,13 @@ void __ref xen_build_mfn_list_list(void)
> 
> 	/* Pre-initialize p2m_top_mfn to be completely missing */
> 	if (p2m_top_mfn == NULL) {
>-		p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+		p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 		p2m_mid_mfn_init(p2m_mid_missing_mfn);
> 
>-		p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+		p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 		p2m_top_mfn_p_init(p2m_top_mfn_p);
> 
>-		p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+		p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 		p2m_top_mfn_init(p2m_top_mfn);
> 	} else {
> 		/* Reinitialise, mfn's all change after migration */
>@@ -322,7 +322,7 @@ void __ref xen_build_mfn_list_list(void)
> 			 * runtime.  extend_brk() will BUG if we call
> 			 * it too late.
> 			 */
>-			mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+			mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 			p2m_mid_mfn_init(mid_mfn_p);
> 
> 			p2m_top_mfn_p[topidx] = mid_mfn_p;
>@@ -351,16 +351,16 @@ void __init
>xen_build_dynamic_phys_to_machine(void)
> 
> 	xen_max_p2m_pfn = max_pfn;
> 
>-	p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+	p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 	p2m_init(p2m_missing);
> 
>-	p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+	p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 	p2m_mid_init(p2m_mid_missing);
> 
>-	p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+	p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 	p2m_top_init(p2m_top);
> 
>-	p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+	p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 	p2m_init(p2m_identity);
> 
> 	/*
>@@ -373,7 +373,8 @@ void __init xen_build_dynamic_phys_to_machine(void)
> 		unsigned mididx = p2m_mid_index(pfn);
> 
> 		if (p2m_top[topidx] == p2m_mid_missing) {
>-			unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+			unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE,
>+							 false);
> 			p2m_mid_init(mid);
> 
> 			p2m_top[topidx] = mid;
>@@ -609,7 +610,7 @@ static bool __init early_alloc_p2m_middle(unsigned
>long pfn, bool check_boundary
> 		return false;
> 
> 	/* Boundary cross-over for the edges: */
>-	p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+	p2m = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 
> 	p2m_init(p2m);
> 
>@@ -635,7 +636,7 @@ static bool __init early_alloc_p2m(unsigned long
>pfn)
> 	mid = p2m_top[topidx];
> 	mid_mfn_p = p2m_top_mfn_p[topidx];
> 	if (mid == p2m_mid_missing) {
>-		mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+		mid = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 
> 		p2m_mid_init(mid);
> 
>@@ -645,7 +646,7 @@ static bool __init early_alloc_p2m(unsigned long
>pfn)
> 	}
> 	/* And the save/restore P2M tables.. */
> 	if (mid_mfn_p == p2m_mid_missing_mfn) {
>-		mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
>+		mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE, false);
> 		p2m_mid_mfn_init(mid_mfn_p);
> 
> 		p2m_top_mfn_p[topidx] = mid_mfn_p;
>@@ -858,7 +859,7 @@ static void __init m2p_override_init(void)
> 	unsigned i;
> 
>	m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
>-				   sizeof(unsigned long));
>+				   sizeof(unsigned long), false);
> 
> 	for (i = 0; i < M2P_OVERRIDE_HASH; i++)
> 		INIT_LIST_HEAD(&m2p_overrides[i]);
>diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
>index 4c1baa7..dff7fcc 100644
>--- a/drivers/acpi/osl.c
>+++ b/drivers/acpi/osl.c
>@@ -563,7 +563,7 @@ RESERVE_BRK(acpi_override_tables_alloc,
>ACPI_OVERRIDE_TABLES_SIZE);
> void __init early_alloc_acpi_override_tables_buf(void)
> {
> 	acpi_tables_addr = __pa(extend_brk(ACPI_OVERRIDE_TABLES_SIZE,
>-					   PAGE_SIZE));
>+					   PAGE_SIZE, false));
> }
> 
> void __init acpi_initrd_override(void *data, size_t size)


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