* [PATCH] x86/efi: Handle errors for efi_map_region_fixed()
@ 2026-08-10 10:22 Eshaan Deshmukh
2026-09-10 7:53 ` Ard Biesheuvel
0 siblings, 1 reply; 2+ messages in thread
From: Eshaan Deshmukh @ 2026-08-10 10:22 UTC (permalink / raw)
To: ardb, tglx, mingo, bp, dave.hansen, x86
Cc: ilias.apalodimas, hpa, linux-efi, linux-kernel, Eshaan Deshmukh
The function efi_map_region_fixed() ignores the errors returned from
kernel_map_pages_in_pgd(). If mapping failes, this can cause page
faults. Update __map_region() and efi_map_region_fixed() to return the
error code from kernel_map_pages_in_pgd(). If there is an error,
efi_map_region_fixed() logs an error message using pr_err(), disables
EFI runtime services, and returns.
Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
---
arch/x86/include/asm/efi.h | 2 +-
arch/x86/platform/efi/efi.c | 10 ++++++++--
arch/x86/platform/efi/efi_32.c | 6 +++++-
arch/x86/platform/efi/efi_64.c | 20 ++++++++++++++------
4 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index be58b7f5c..04952e064 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -128,7 +128,7 @@ extern bool efi_disable_ibt_for_runtime;
extern int __init efi_memblock_x86_reserve_range(void);
extern void __init efi_print_memmap(void);
extern void __init efi_map_region(efi_memory_desc_t *md);
-extern void __init efi_map_region_fixed(efi_memory_desc_t *md);
+extern int __init efi_map_region_fixed(efi_memory_desc_t *md);
extern void efi_sync_low_kernel_mappings(void);
extern int __init efi_alloc_page_tables(void);
extern int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages);
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0c39adb96..4b875843a 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -735,8 +735,14 @@ static void __init kexec_enter_virtual_mode(void)
* Map efi regions which were passed via setup_data. The virt_addr is a
* fixed addr which was used in first kernel of a kexec boot.
*/
- for_each_efi_memory_desc(md)
- efi_map_region_fixed(md); /* FIXME: add error handling */
+ for_each_efi_memory_desc(md) {
+ if (efi_map_region_fixed(md)) {
+ pr_err("Failed to map fixed EFI region\n");
+ clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
+ return;
+ }
+
+ }
/*
* Unregister the early EFI memmap from efi_init() and install
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index b2cc7b455..9307999b9 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -84,7 +84,11 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
return 0;
}
-void __init efi_map_region_fixed(efi_memory_desc_t *md) {}
+int __init efi_map_region_fixed(efi_memory_desc_t *md)
+{
+ return 0;
+}
+
void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}
efi_status_t efi_call_svam(efi_runtime_services_t * const *,
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 5861008ea..05f1df6ca 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -269,12 +269,12 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
return 0;
}
-static void __init __map_region(efi_memory_desc_t *md, u64 va)
+static int __init __map_region(efi_memory_desc_t *md, u64 va)
{
unsigned long flags = _PAGE_RW;
unsigned long pfn;
pgd_t *pgd = efi_mm.pgd;
-
+ int error;
/*
* EFI_RUNTIME_SERVICES_CODE regions typically cover PE/COFF
* executable images in memory that consist of both R-X and
@@ -299,9 +299,11 @@ static void __init __map_region(efi_memory_desc_t *md, u64 va)
flags |= _PAGE_ENC;
pfn = md->phys_addr >> PAGE_SHIFT;
- if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
+ error = kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags);
+ if (error)
pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
md->phys_addr, va);
+ return error;
}
void __init efi_map_region(efi_memory_desc_t *md)
@@ -357,10 +359,16 @@ void __init efi_map_region(efi_memory_desc_t *md)
* md->virt_addr is the original virtual address which had been mapped in kexec
* 1st kernel.
*/
-void __init efi_map_region_fixed(efi_memory_desc_t *md)
+int __init efi_map_region_fixed(efi_memory_desc_t *md)
{
- __map_region(md, md->phys_addr);
- __map_region(md, md->virt_addr);
+ int error;
+
+ error = __map_region(md, md->phys_addr);
+
+ if (error)
+ return error;
+
+ return __map_region(md, md->virt_addr);
}
void __init parse_efi_setup(u64 phys_addr, u32 data_len)
--
2.55.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] x86/efi: Handle errors for efi_map_region_fixed()
2026-08-10 10:22 [PATCH] x86/efi: Handle errors for efi_map_region_fixed() Eshaan Deshmukh
@ 2026-09-10 7:53 ` Ard Biesheuvel
0 siblings, 0 replies; 2+ messages in thread
From: Ard Biesheuvel @ 2026-09-10 7:53 UTC (permalink / raw)
To: Eshaan Deshmukh, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
dave.hansen, x86
Cc: Ilias Apalodimas, H . Peter Anvin, linux-efi, linux-kernel
Hello Eshaan,
On Mon, 10 Aug 2026, at 12:22, Eshaan Deshmukh wrote:
> The function efi_map_region_fixed() ignores the errors returned from
> kernel_map_pages_in_pgd(). If mapping failes, this can cause page
> faults. Update __map_region() and efi_map_region_fixed() to return the
> error code from kernel_map_pages_in_pgd(). If there is an error,
> efi_map_region_fixed() logs an error message using pr_err(), disables
> EFI runtime services, and returns.
>
Does this solve an actual problem that you observed?
> Signed-off-by: Eshaan Deshmukh <eshaan2031@icloud.com>
> ---
> arch/x86/include/asm/efi.h | 2 +-
> arch/x86/platform/efi/efi.c | 10 ++++++++--
> arch/x86/platform/efi/efi_32.c | 6 +++++-
> arch/x86/platform/efi/efi_64.c | 20 ++++++++++++++------
> 4 files changed, 28 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index be58b7f5c..04952e064 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -128,7 +128,7 @@ extern bool efi_disable_ibt_for_runtime;
> extern int __init efi_memblock_x86_reserve_range(void);
> extern void __init efi_print_memmap(void);
> extern void __init efi_map_region(efi_memory_desc_t *md);
> -extern void __init efi_map_region_fixed(efi_memory_desc_t *md);
> +extern int __init efi_map_region_fixed(efi_memory_desc_t *md);
> extern void efi_sync_low_kernel_mappings(void);
> extern int __init efi_alloc_page_tables(void);
> extern int __init efi_setup_page_tables(unsigned long pa_memmap,
> unsigned num_pages);
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index 0c39adb96..4b875843a 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -735,8 +735,14 @@ static void __init kexec_enter_virtual_mode(void)
> * Map efi regions which were passed via setup_data. The virt_addr is a
> * fixed addr which was used in first kernel of a kexec boot.
> */
> - for_each_efi_memory_desc(md)
> - efi_map_region_fixed(md); /* FIXME: add error handling */
> + for_each_efi_memory_desc(md) {
> + if (efi_map_region_fixed(md)) {
> + pr_err("Failed to map fixed EFI region\n");
> + clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);
> + return;
> + }
> +
> + }
>
> /*
> * Unregister the early EFI memmap from efi_init() and install
> diff --git a/arch/x86/platform/efi/efi_32.c
> b/arch/x86/platform/efi/efi_32.c
> index b2cc7b455..9307999b9 100644
> --- a/arch/x86/platform/efi/efi_32.c
> +++ b/arch/x86/platform/efi/efi_32.c
> @@ -84,7 +84,11 @@ int __init efi_setup_page_tables(unsigned long
> pa_memmap, unsigned num_pages)
> return 0;
> }
>
> -void __init efi_map_region_fixed(efi_memory_desc_t *md) {}
> +int __init efi_map_region_fixed(efi_memory_desc_t *md)
> +{
> + return 0;
> +}
> +
> void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}
>
> efi_status_t efi_call_svam(efi_runtime_services_t * const *,
> diff --git a/arch/x86/platform/efi/efi_64.c
> b/arch/x86/platform/efi/efi_64.c
> index 5861008ea..05f1df6ca 100644
> --- a/arch/x86/platform/efi/efi_64.c
> +++ b/arch/x86/platform/efi/efi_64.c
> @@ -269,12 +269,12 @@ int __init efi_setup_page_tables(unsigned long
> pa_memmap, unsigned num_pages)
> return 0;
> }
>
> -static void __init __map_region(efi_memory_desc_t *md, u64 va)
> +static int __init __map_region(efi_memory_desc_t *md, u64 va)
> {
> unsigned long flags = _PAGE_RW;
> unsigned long pfn;
> pgd_t *pgd = efi_mm.pgd;
> -
> + int error;
> /*
> * EFI_RUNTIME_SERVICES_CODE regions typically cover PE/COFF
> * executable images in memory that consist of both R-X and
> @@ -299,9 +299,11 @@ static void __init __map_region(efi_memory_desc_t
> *md, u64 va)
> flags |= _PAGE_ENC;
>
> pfn = md->phys_addr >> PAGE_SHIFT;
> - if (kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags))
> + error = kernel_map_pages_in_pgd(pgd, pfn, va, md->num_pages, flags);
> + if (error)
> pr_warn("Error mapping PA 0x%llx -> VA 0x%llx!\n",
> md->phys_addr, va);
> + return error;
> }
>
> void __init efi_map_region(efi_memory_desc_t *md)
> @@ -357,10 +359,16 @@ void __init efi_map_region(efi_memory_desc_t *md)
> * md->virt_addr is the original virtual address which had been mapped in kexec
> * 1st kernel.
> */
> -void __init efi_map_region_fixed(efi_memory_desc_t *md)
> +int __init efi_map_region_fixed(efi_memory_desc_t *md)
> {
> - __map_region(md, md->phys_addr);
> - __map_region(md, md->virt_addr);
> + int error;
> +
> + error = __map_region(md, md->phys_addr);
> +
> + if (error)
> + return error;
> +
> + return __map_region(md, md->virt_addr);
> }
>
> void __init parse_efi_setup(u64 phys_addr, u32 data_len)
> --
> 2.55.0
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-08-10 10:22 [PATCH] x86/efi: Handle errors for efi_map_region_fixed() Eshaan Deshmukh
2026-09-10 7:53 ` Ard Biesheuvel
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