[10/16] x86/boot: Make console interface more abstract

To be able to extract kernel from EFI, console output functions
need to be replaceable by alternative implementations.

Make all of those functions pointers.
Move serial console code to separate file.

Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
---
 arch/x86/boot/compressed/Makefile       |   2 +-
 arch/x86/boot/compressed/ident_map_64.c |  15 ++-
 arch/x86/boot/compressed/misc.c         | 109 +--------------------
 arch/x86/boot/compressed/misc.h         |  13 ++-
 arch/x86/boot/compressed/putstr.c       | 124 ++++++++++++++++++++++++
 5 files changed, 146 insertions(+), 117 deletions(-)
 create mode 100644 arch/x86/boot/compressed/putstr.c

On Tue, 6 Sept 2022 at 12:42, Evgeniy Baskov <baskov@ispras.ru> wrote:
>
> To be able to extract kernel from EFI, console output functions
> need to be replaceable by alternative implementations.
>
> Make all of those functions pointers.
> Move serial console code to separate file.
>

What does kernel_add_identity_map() have to do with the above? Should
that be a separate patch?

> Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
> ---
>  arch/x86/boot/compressed/Makefile       |   2 +-
>  arch/x86/boot/compressed/ident_map_64.c |  15 ++-
>  arch/x86/boot/compressed/misc.c         | 109 +--------------------
>  arch/x86/boot/compressed/misc.h         |  13 ++-
>  arch/x86/boot/compressed/putstr.c       | 124 ++++++++++++++++++++++++
>  5 files changed, 146 insertions(+), 117 deletions(-)
>  create mode 100644 arch/x86/boot/compressed/putstr.c
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 35ce1a64068b..29411864bfcd 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -92,7 +92,7 @@ $(obj)/misc.o: $(obj)/../voffset.h
>
>  vmlinux-objs-y := $(obj)/vmlinux.lds $(obj)/kernel_info.o $(obj)/head_$(BITS).o \
>         $(obj)/misc.o $(obj)/string.o $(obj)/cmdline.o $(obj)/error.o \
> -       $(obj)/piggy.o $(obj)/cpuflags.o
> +       $(obj)/piggy.o $(obj)/cpuflags.o $(obj)/putstr.o
>
>  vmlinux-objs-$(CONFIG_EARLY_PRINTK) += $(obj)/early_serial_console.o
>  vmlinux-objs-$(CONFIG_RANDOMIZE_BASE) += $(obj)/kaslr.o
> diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c
> index c20cd31e665f..c39373687e50 100644
> --- a/arch/x86/boot/compressed/ident_map_64.c
> +++ b/arch/x86/boot/compressed/ident_map_64.c
> @@ -89,12 +89,20 @@ phys_addr_t physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1;
>  static struct x86_mapping_info mapping_info;
>  int has_nx;
>
> +/*
> + * This points to actual implementation of mapping function.
> + * Either the one down below or the UEFI API wrapper.
> + */
> +unsigned long (*kernel_add_identity_map)(unsigned long start,
> +                                        unsigned long end,
> +                                        unsigned int flags);
> +
>  /*
>   * Adds the specified range to the identity mappings.
>   */
> -unsigned long kernel_add_identity_map(unsigned long start,
> -                                     unsigned long end,
> -                                     unsigned int flags)
> +unsigned long kernel_add_identity_map_(unsigned long start,
> +                                      unsigned long end,
> +                                      unsigned int flags)
>  {
>         int ret;
>
> @@ -136,6 +144,7 @@ void initialize_identity_maps(void *rmode)
>         struct setup_data *sd;
>
>         boot_params = rmode;
> +       kernel_add_identity_map = kernel_add_identity_map_;
>
>         /* Exclude the encryption mask from __PHYSICAL_MASK */
>         physical_mask &= ~sme_me_mask;
> diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
> index d377e434c4e3..e2c0d05ac293 100644
> --- a/arch/x86/boot/compressed/misc.c
> +++ b/arch/x86/boot/compressed/misc.c
> @@ -53,13 +53,6 @@ struct port_io_ops pio_ops;
>  memptr free_mem_ptr;
>  memptr free_mem_end_ptr;
>
> -static char *vidmem;
> -static int vidport;
> -
> -/* These might be accessed before .bss is cleared, so use .data instead. */
> -static int lines __section(".data");
> -static int cols __section(".data");
> -
>  #ifdef CONFIG_KERNEL_GZIP
>  #include "../../../../lib/decompress_inflate.c"
>  #endif
> @@ -92,95 +85,6 @@ static int cols __section(".data");
>   * ../header.S.
>   */
>
> -static void scroll(void)
> -{
> -       int i;
> -
> -       memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
> -       for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
> -               vidmem[i] = ' ';
> -}
> -
> -#define XMTRDY          0x20
> -
> -#define TXR             0       /*  Transmit register (WRITE) */
> -#define LSR             5       /*  Line Status               */
> -static void serial_putchar(int ch)
> -{
> -       unsigned timeout = 0xffff;
> -
> -       while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
> -               cpu_relax();
> -
> -       outb(ch, early_serial_base + TXR);
> -}
> -
> -void __putstr(const char *s)
> -{
> -       int x, y, pos;
> -       char c;
> -
> -       if (early_serial_base) {
> -               const char *str = s;
> -               while (*str) {
> -                       if (*str == '\n')
> -                               serial_putchar('\r');
> -                       serial_putchar(*str++);
> -               }
> -       }
> -
> -       if (lines == 0 || cols == 0)
> -               return;
> -
> -       x = boot_params->screen_info.orig_x;
> -       y = boot_params->screen_info.orig_y;
> -
> -       while ((c = *s++) != '\0') {
> -               if (c == '\n') {
> -                       x = 0;
> -                       if (++y >= lines) {
> -                               scroll();
> -                               y--;
> -                       }
> -               } else {
> -                       vidmem[(x + cols * y) * 2] = c;
> -                       if (++x >= cols) {
> -                               x = 0;
> -                               if (++y >= lines) {
> -                                       scroll();
> -                                       y--;
> -                               }
> -                       }
> -               }
> -       }
> -
> -       boot_params->screen_info.orig_x = x;
> -       boot_params->screen_info.orig_y = y;
> -
> -       pos = (x + cols * y) * 2;       /* Update cursor position */
> -       outb(14, vidport);
> -       outb(0xff & (pos >> 9), vidport+1);
> -       outb(15, vidport);
> -       outb(0xff & (pos >> 1), vidport+1);
> -}
> -
> -void __puthex(unsigned long value)
> -{
> -       char alpha[2] = "0";
> -       int bits;
> -
> -       for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
> -               unsigned long digit = (value >> bits) & 0xf;
> -
> -               if (digit < 0xA)
> -                       alpha[0] = '0' + digit;
> -               else
> -                       alpha[0] = 'a' + (digit - 0xA);
> -
> -               __putstr(alpha);
> -       }
> -}
> -
>  #ifdef CONFIG_X86_NEED_RELOCS
>  static void handle_relocations(void *output, unsigned long output_len,
>                                unsigned long virt_addr)
> @@ -407,17 +311,6 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
>
>         sanitize_boot_params(boot_params);
>
> -       if (boot_params->screen_info.orig_video_mode == 7) {
> -               vidmem = (char *) 0xb0000;
> -               vidport = 0x3b4;
> -       } else {
> -               vidmem = (char *) 0xb8000;
> -               vidport = 0x3d4;
> -       }
> -
> -       lines = boot_params->screen_info.orig_video_lines;
> -       cols = boot_params->screen_info.orig_video_cols;
> -
>         init_default_io_ops();
>
>         /*
> @@ -428,7 +321,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
>          */
>         early_tdx_detect();
>
> -       console_init();
> +       init_bare_console();
>
>         /*
>          * Save RSDP address for later use. Have this after console_init()
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index a4f99516f310..39dc3de50268 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -53,8 +53,8 @@ extern memptr free_mem_end_ptr;
>  void *malloc(int size);
>  void free(void *where);
>  extern struct boot_params *boot_params;
> -void __putstr(const char *s);
> -void __puthex(unsigned long value);
> +extern void (*__putstr)(const char *s);
> +extern void (*__puthex)(unsigned long value);
>  #define error_putstr(__x)  __putstr(__x)
>  #define error_puthex(__x)  __puthex(__x)
>
> @@ -124,6 +124,9 @@ static inline void console_init(void)
>  { }
>  #endif
>
> +/* putstr.c */
> +void init_bare_console(void);
> +
>  #ifdef CONFIG_AMD_MEM_ENCRYPT
>  void sev_enable(struct boot_params *bp);
>  void sev_es_shutdown_ghcb(void);
> @@ -172,9 +175,9 @@ static inline int count_immovable_mem_regions(void) { return 0; }
>  extern unsigned int __pgtable_l5_enabled, pgdir_shift, ptrs_per_p4d;
>  #endif
>  #ifdef CONFIG_X86_64
> -extern unsigned long kernel_add_identity_map(unsigned long start,
> -                                            unsigned long end,
> -                                            unsigned int flags);
> +extern unsigned long (*kernel_add_identity_map)(unsigned long start,
> +                                               unsigned long end,
> +                                               unsigned int flags);
>  #else
>  static inline unsigned long kernel_add_identity_map(unsigned long start,
>                                                     unsigned long end,
> diff --git a/arch/x86/boot/compressed/putstr.c b/arch/x86/boot/compressed/putstr.c
> new file mode 100644
> index 000000000000..accba0de8be9
> --- /dev/null
> +++ b/arch/x86/boot/compressed/putstr.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include "misc.h"
> +
> +/* These might be accessed before .bss is cleared, so use .data instead. */
> +static char *vidmem __section(".data");
> +static int vidport __section(".data");
> +static int lines __section(".data");
> +static int cols __section(".data");
> +
> +void (*__putstr)(const char *s);
> +void (*__puthex)(unsigned long value);
> +
> +static void putstr(const char *s);
> +static void puthex(unsigned long value);
> +
> +void init_bare_console(void)
> +{
> +       __putstr = putstr;
> +       __puthex = puthex;
> +
> +       if (boot_params->screen_info.orig_video_mode == 7) {
> +               vidmem = (char *) 0xb0000;
> +               vidport = 0x3b4;
> +       } else {
> +               vidmem = (char *) 0xb8000;
> +               vidport = 0x3d4;
> +       }
> +
> +       lines = boot_params->screen_info.orig_video_lines;
> +       cols = boot_params->screen_info.orig_video_cols;
> +
> +       console_init();
> +}
> +
> +static void scroll(void)
> +{
> +       int i;
> +
> +       memmove(vidmem, vidmem + cols * 2, (lines - 1) * cols * 2);
> +       for (i = (lines - 1) * cols * 2; i < lines * cols * 2; i += 2)
> +               vidmem[i] = ' ';
> +}
> +
> +#define XMTRDY          0x20
> +
> +#define TXR             0       /*  Transmit register (WRITE) */
> +#define LSR             5       /*  Line Status               */
> +
> +static void serial_putchar(int ch)
> +{
> +       unsigned int timeout = 0xffff;
> +
> +       while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
> +               cpu_relax();
> +
> +       outb(ch, early_serial_base + TXR);
> +}
> +
> +static void putstr(const char *s)
> +{
> +       int x, y, pos;
> +       char c;
> +
> +       if (early_serial_base) {
> +               const char *str = s;
> +
> +               while (*str) {
> +                       if (*str == '\n')
> +                               serial_putchar('\r');
> +                       serial_putchar(*str++);
> +               }
> +       }
> +
> +       if (lines == 0 || cols == 0)
> +               return;
> +
> +       x = boot_params->screen_info.orig_x;
> +       y = boot_params->screen_info.orig_y;
> +
> +       while ((c = *s++) != '\0') {
> +               if (c == '\n') {
> +                       x = 0;
> +                       if (++y >= lines) {
> +                               scroll();
> +                               y--;
> +                       }
> +               } else {
> +                       vidmem[(x + cols * y) * 2] = c;
> +                       if (++x >= cols) {
> +                               x = 0;
> +                               if (++y >= lines) {
> +                                       scroll();
> +                                       y--;
> +                               }
> +                       }
> +               }
> +       }
> +
> +       boot_params->screen_info.orig_x = x;
> +       boot_params->screen_info.orig_y = y;
> +
> +       pos = (x + cols * y) * 2;       /* Update cursor position */
> +       outb(14, vidport);
> +       outb(0xff & (pos >> 9), vidport+1);
> +       outb(15, vidport);
> +       outb(0xff & (pos >> 1), vidport+1);
> +}
> +
> +static void puthex(unsigned long value)
> +{
> +       char alpha[2] = "0";
> +       int bits;
> +
> +       for (bits = sizeof(value) * 8 - 4; bits >= 0; bits -= 4) {
> +               unsigned long digit = (value >> bits) & 0xf;
> +
> +               if (digit < 0xA)
> +                       alpha[0] = '0' + digit;
> +               else
> +                       alpha[0] = 'a' + (digit - 0xA);
> +
> +               putstr(alpha);
> +       }
> +}
> --
> 2.35.1
>

On 2022-10-19 10:23, Ard Biesheuvel wrote:
> On Tue, 6 Sept 2022 at 12:42, Evgeniy Baskov <baskov@ispras.ru> wrote:
>> 
>> To be able to extract kernel from EFI, console output functions
>> need to be replaceable by alternative implementations.
>> 
>> Make all of those functions pointers.
>> Move serial console code to separate file.
>> 
> 
> What does kernel_add_identity_map() have to do with the above? Should
> that be a separate patch?

It used to be dependent, but no longer is.
I'll split making kernel_add_identity_map() a function pointer
out into separate patch.

> 
>> Signed-off-by: Evgeniy Baskov <baskov@ispras.ru>
>> ---
>>  arch/x86/boot/compressed/Makefile       |   2 +-
>>  arch/x86/boot/compressed/ident_map_64.c |  15 ++-
>>  arch/x86/boot/compressed/misc.c         | 109 +--------------------
>>  arch/x86/boot/compressed/misc.h         |  13 ++-
>>  arch/x86/boot/compressed/putstr.c       | 124 
>> ++++++++++++++++++++++++
>>  5 files changed, 146 insertions(+), 117 deletions(-)
>>  create mode 100644 arch/x86/boot/compressed/putstr.c
...