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From: Ard Biesheuvel <ardb@kernel.org>
To: Joe Perches <joe@perches.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-efi <linux-efi@vger.kernel.org>, X86 ML <x86@kernel.org>
Subject: Re: [trivial PATCH] efi/libstub: Reduce efi_printk object size
Date: Tue, 5 May 2020 09:50:58 +0200
Message-ID: <CAMj1kXGQ7dLNMnheWViBh7BnHd00kWw0AW2aF7i7S2wGti0qKg@mail.gmail.com> (raw)
In-Reply-To: <f1926d434cdeb091405ef8c01a90c0140d296bed.camel@perches.com>

On Mon, 4 May 2020 at 20:29, Joe Perches <joe@perches.com> wrote:
>
> Use a few more common kernel styles.
>
> Trivially reduce efi_printk object size by using a dereference to
> a temporary instead of multiple dereferences of the same object.
>
> Use efi_printk(const char *str) and static or static const for its
> internal variables.
>
> Use the more common form of while instead of a for loop.
>
> Change efi_char16_printk argument to const.
>
> Signed-off-by: Joe Perches <joe@perches.com>

Thanks Joe.


> ---
>  drivers/firmware/efi/libstub/efi-stub-helper.c | 16 ++++++++--------
>  drivers/firmware/efi/libstub/efistub.h         |  6 +++---
>  2 files changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
> index 1c92ac231f94..dfd72a4360ac 100644
> --- a/drivers/firmware/efi/libstub/efi-stub-helper.c
> +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
> @@ -26,19 +26,19 @@ bool __pure __efi_soft_reserve_enabled(void)
>         return !efi_nosoftreserve;
>  }
>
> -void efi_printk(char *str)
> +void efi_printk(const char *str)
>  {
> -       char *s8;
> +       char s8;
>
> -       for (s8 = str; *s8; s8++) {
> -               efi_char16_t ch[2] = { 0 };
> +       while ((s8 = *str++)) {

I'm not sure I prefer the assignment-as-truth-value construct over the
original for () tbh

> +               static efi_char16_t ch[2] = {0, 0};
>

UEFI code could potentially be reentrant, so this should not be static.

> -               ch[0] = *s8;
> -               if (*s8 == '\n') {
> -                       efi_char16_t nl[2] = { '\r', 0 };
> +               if (s8 == '\n') {
> +                       static const efi_char16_t nl[2] = { '\r', 0 };
>                         efi_char16_printk(nl);

We cannot make this const, unfortunately (see below). But we can clean
this up by using L"\r" as the initializer.

>                 }
>
> +               ch[0] = s8;
>                 efi_char16_printk(ch);
>         }
>  }
> @@ -284,7 +284,7 @@ void *get_efi_config_table(efi_guid_t guid)
>         return NULL;
>  }
>
> -void efi_char16_printk(efi_char16_t *str)
> +void efi_char16_printk(const efi_char16_t *str)
>  {
>         efi_call_proto(efi_table_attr(efi_system_table, con_out),
>                        output_string, str);
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 5ff63230a1f1..a03a92c665f0 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -251,7 +251,7 @@ union efi_simple_text_output_protocol {
>         struct {
>                 void *reset;
>                 efi_status_t (__efiapi *output_string)(efi_simple_text_output_protocol_t *,
> -                                                      efi_char16_t *);
> +                                                      const efi_char16_t *);

This prototype comes straight from the UEFI specification, and even
though it is dumb that they forgot about const-qualified pointers
entirely, I would prefer not to deviate from this.

>                 void *test_string;
>         };
>         struct {
> @@ -599,7 +599,7 @@ efi_status_t efi_exit_boot_services(void *handle,
>                                     void *priv,
>                                     efi_exit_boot_map_processing priv_func);
>
> -void efi_char16_printk(efi_char16_t *);
> +void efi_char16_printk(const efi_char16_t *str);
>
>  efi_status_t allocate_new_fdt_and_exit_boot(void *handle,
>                                             unsigned long *new_fdt_addr,
> @@ -624,7 +624,7 @@ efi_status_t check_platform_features(void);
>
>  void *get_efi_config_table(efi_guid_t guid);
>
> -void efi_printk(char *str);
> +void efi_printk(const char *str);
>
>  void efi_free(unsigned long size, unsigned long addr);
>
>

  reply index

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-29 17:41 [PATCH 00/10] efi: some cleanups/refactoring for efi/next Arvind Sankar
2020-04-29 17:41 ` [PATCH 01/10] efi/x86: Use correct size for boot_params Arvind Sankar
2020-04-29 17:41 ` [PATCH 02/10] efi: Add a helper function to split 64-bit values Arvind Sankar
2020-04-29 23:51   ` kbuild test robot
2020-04-29 17:41 ` [PATCH 02/10] efi/libstub: " Arvind Sankar
2020-04-29 17:41 ` [PATCH 03/10] efi/x86: Use pr_efi_err for error messages Arvind Sankar
2020-04-29 18:47   ` Joe Perches
2020-04-29 18:49     ` Ard Biesheuvel
2020-04-29 18:57       ` Joe Perches
2020-04-29 18:59         ` Ard Biesheuvel
2020-04-29 19:47           ` Joe Perches
2020-04-29 19:48             ` Ard Biesheuvel
2020-04-29 21:43       ` Arvind Sankar
2020-04-29 21:45         ` Ard Biesheuvel
2020-04-29 21:51           ` Arvind Sankar
2020-04-29 21:53         ` Joe Perches
2020-04-29 21:55           ` Ard Biesheuvel
2020-04-29 22:20             ` Arvind Sankar
2020-04-30 15:14               ` Ard Biesheuvel
2020-04-29 17:41 ` [PATCH 04/10] efi/gop: " Arvind Sankar
2020-04-29 17:41 ` [PATCH 05/10] efi/tpm: " Arvind Sankar
2020-04-29 17:41 ` [PATCH 06/10] efi/x86: Move command-line initrd loading to efi_main Arvind Sankar
2020-04-29 17:41 ` [PATCH 07/10] efi/libstub: Unify initrd loading across architectures Arvind Sankar
2020-04-29 17:41 ` [PATCH 08/10] efi/x86: Drop soft_limit for x86 initrd loading Arvind Sankar
2020-04-29 19:05   ` Ard Biesheuvel
2020-04-29 21:33     ` Arvind Sankar
2020-04-29 17:41 ` [PATCH 09/10] efi/x86: Support builtin command line Arvind Sankar
2020-04-29 19:07   ` Ard Biesheuvel
2020-04-29 21:39     ` Arvind Sankar
2020-04-29 21:40       ` Ard Biesheuvel
2020-04-29 21:48         ` Arvind Sankar
2020-04-29 21:51           ` Ard Biesheuvel
2020-04-29 17:41 ` [PATCH 10/10] efi/libstub: Check return value of efi_parse_options Arvind Sankar
2020-04-30  4:31   ` kbuild test robot
2020-04-30 18:28 ` [PATCH v2 00/11] efi: some cleanups/refactoring for efi/next Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 01/11] efi/x86: Use correct size for boot_params Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 02/11] efi/libstub: Add a helper function to split 64-bit values Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 03/11] efi/libstub: Move pr_efi/pr_efi_err into efi namespace Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 04/11] efi/x86: Use efi_err for error messages Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 05/11] efi/gop: " Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 06/11] efi/tpm: " Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 07/11] efi/libstub: Upgrade ignored dtb= argument message to error Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 08/11] efi/x86: Move command-line initrd loading to efi_main Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 09/11] efi/libstub: Unify initrd loading across architectures Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 10/11] efi/x86: Support builtin command line Arvind Sankar
2020-04-30 18:28   ` [PATCH v2 11/11] efi/libstub: Check return value of efi_parse_options Arvind Sankar
2020-04-30 19:12   ` [PATCH 1/2] efi/libstub: efi_info/efi_err message neatening Joe Perches
2020-04-30 19:12     ` [PATCH 2/2] efi/libstub: Correct comment typos Joe Perches
2020-04-30 19:30       ` Ard Biesheuvel
2020-05-04 18:29         ` [trivial PATCH] efi/libstub: Reduce efi_printk object size Joe Perches
2020-05-05  7:50           ` Ard Biesheuvel [this message]
2020-05-05  8:01             ` Joe Perches
2020-04-30 19:29     ` [PATCH 1/2] efi/libstub: efi_info/efi_err message neatening Ard Biesheuvel
2020-04-30 19:38       ` Joe Perches
2020-04-30 20:40       ` Arvind Sankar
2020-04-30 20:42         ` Ard Biesheuvel
2020-05-04  8:17   ` [PATCH v2 00/11] efi: some cleanups/refactoring for efi/next Ard Biesheuvel

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