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Date: Wed, 08 Feb 2012 18:31:54 +0000
From: Matt Fleming <matt.fleming@...el.com>
To: Olof Johansson <olof@...om.net>
Cc: x86@...nel.org, hpa@...or.com, mingo@...e.hu, tglx@...utronix.de,
linux-kernel@...r.kernel.org, mjg@...hat.com
Subject: Re: [PATCH 5/5] x86: efi: allow basic init with mixed 32/64-bit
efi/kernel
On Tue, 2012-02-07 at 16:25 -0800, Olof Johansson wrote:
> Traditionally the kernel has refused to setup EFI at all if there's been
> a mismatch in 32/64-bit mode between EFI and the kernel.
>
> On some platforms that boot natively through EFI (Chrome OS being one),
> we still need to get at least some of the static data such as memory
> configuration out of EFI. Runtime services aren't as critical, and
> it's a significant amount of work to implement switching between the
> operating modes to call between kernel and firmware for thise cases. So
> I'm ignoring it for now.
Presumably with these patches in mainline you can get rid of the hacks
that ChromeOS currently uses?
> v4:
> * Some of the earlier cleanup was accidentally reverted by this patch, fixed.
> * Reworded some messages to not have to line wrap printk strings
>
> v3:
> * Reorganized to a series of patches to make it easier to review, and
> do some of the cleanups I had left out before.
>
> v2:
> * Added graceful error handling for 32-bit kernel that gets passed
> EFI data above 4GB.
> * Removed some warnings that were missed in first version.
>
> Signed-off-by: Olof Johansson <olof@...om.net>
> ---
> arch/x86/include/asm/efi.h | 2 +-
> arch/x86/kernel/setup.c | 10 ++-
> arch/x86/platform/efi/efi.c | 164 +++++++++++++++++++++++++++++++++++++------
> include/linux/efi.h | 45 ++++++++++++
> 4 files changed, 195 insertions(+), 26 deletions(-)
>
[...]
> +
> + early_iounmap(systab64, sizeof(*systab64));
> +#ifdef CONFIG_X86_32
> + if (tmp >> 32) {
> + pr_err("EFI data located above 4GB, disabling.\n");
> + return -EINVAL;
> + }
> +#endif
You should really say "disabling EFI" here.
[...]
> +#ifdef CONFIG_X86_32
> + if (table64 >> 32) {
> + pr_cont("\n");
> + pr_err("Table located above 4GB, disabling.\n");
> + early_iounmap(config_tables,
> + efi.systab->nr_tables * sz);
> + return -EINVAL;
> + }
> +#endif
Likewise here, mention that you're disabling EFI.
[...]
> @@ -576,11 +670,19 @@ void __init efi_init(void)
> void *tmp;
>
> #ifdef CONFIG_X86_32
> + if (boot_params.efi_info.efi_systab_hi ||
> + boot_params.efi_info.efi_memmap_hi) {
> + pr_info("Table located above 4GB, disabling.\n");
> + efi_enabled = 0;
> + return;
> + }
> efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
> + efi_native = !efi_64bit;
> #else
... and here
> efi_phys.systab = (efi_system_table_t *)
> - (boot_params.efi_info.efi_systab |
> - ((__u64)boot_params.efi_info.efi_systab_hi<<32));
> + (boot_params.efi_info.efi_systab |
> + ((__u64)boot_params.efi_info.efi_systab_hi<<32));
> + efi_native = efi_64bit;
> #endif
>
> if (efi_systab_init(efi_phys.systab)) {
> @@ -609,19 +711,26 @@ void __init efi_init(void)
> return;
> }
>
> - if (efi_runtime_init()) {
> + /*
> + * Note: We currently don't support runtime services on an EFI
> + * that doesn't match the kernel 32/64-bit mode.
> + */
> +
> + if (efi_native && efi_runtime_init()) {
> efi_enabled = 0;
> return;
> - }
> + } else
> + pr_info("No EFI runtime due to 32/64b mismatch with kernel\n");
Hmm... this isn't right. efi_runtime_init() returns 0 on success, so
you're printing this warning in the native EFI success path. Also,
please spell out "32/64-bit".
> @@ -679,6 +788,13 @@ void __init efi_enter_virtual_mode(void)
>
> efi.systab = NULL;
>
> + /* We don't do virtual mode, since we don't do runtime services, on
> + * non-native EFI
> + */
> +
> + if (!efi_native)
> + goto out;
> +
/*
* Multi-line comments should look like this.
*/
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 37c3007..17385ba 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -315,6 +315,16 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
>
> typedef struct {
> efi_guid_t guid;
> + u64 table;
> +} _efi_config_table_64_t;
> +
> +typedef struct {
> + efi_guid_t guid;
> + u32 table;
> +} _efi_config_table_32_t;
> +
> +typedef struct {
> + efi_guid_t guid;
> unsigned long table;
> } efi_config_table_t;
There's no need for the underscore prefix on these names.
efi_config_table_64_t, etc, is fine. Normally you should try to avoid
adding new typedefs, but I think these make sense because they're an
extension of existing typedefs.
Actually, thinking about it some more, it would make more sense to just
delete efi_config_table_t and efi_system_table_t and make everyone
explicitly pick a size, not least because it will make people adding new
code think long and hard about the mixed mode case.
> @@ -329,6 +339,40 @@ typedef struct {
>
> typedef struct {
> efi_table_hdr_t hdr;
> + u64 fw_vendor; /* physical addr of CHAR16 vendor string */
> + u32 fw_revision;
> + u32 __pad1;
> + u64 con_in_handle;
> + u64 con_in;
> + u64 con_out_handle;
> + u64 con_out;
> + u64 stderr_handle;
> + u64 stderr;
> + u64 runtime;
> + u64 boottime;
> + u32 nr_tables;
> + u32 __pad2;
> + u64 tables;
> +} _efi_system_table_64_t;
No underscore please.
> +typedef struct {
> + efi_table_hdr_t hdr;
> + u32 fw_vendor; /* physical addr of CHAR16 vendor string */
> + u32 fw_revision;
> + u32 con_in_handle;
> + u32 con_in;
> + u32 con_out_handle;
> + u32 con_out;
> + u32 stderr_handle;
> + u32 stderr;
> + u32 runtime;
> + u32 boottime;
> + u32 nr_tables;
> + u32 tables;
> +} _efi_system_table_32_t;
Same here.
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