Re: [PATCH v2 5/8] hw/mips: Use bl_gen_kernel_jump to generate bootloaders

[Jiaxun Yang]

在 2021/1/7 上午1:48, Philippe Mathieu-Daudé 写道:
> +Alex
>
> On 12/15/20 7:45 AM, Jiaxun Yang wrote:
> > Replace embedded binary with generated code.
> >
> > Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> > ---
> >   hw/mips/boston.c    | 17 ++---------------
> >   hw/mips/fuloong2e.c | 28 ++++------------------------
> >   hw/mips/malta.c     | 41 ++++++++++-------------------------------
> >   3 files changed, 16 insertions(+), 70 deletions(-)
> >
> > diff --git a/hw/mips/boston.c b/hw/mips/boston.c
> > index c3b94c68e1..b622222c7d 100644
> > --- a/hw/mips/boston.c
> > +++ b/hw/mips/boston.c
> > @@ -27,6 +27,7 @@
> >   #include "hw/ide/ahci.h"
> >   #include "hw/loader.h"
> >   #include "hw/loader-fit.h"
> > +#include "hw/mips/bootloader.h"
> >   #include "hw/mips/cps.h"
> >   #include "hw/pci-host/xilinx-pcie.h"
> >   #include "hw/qdev-clock.h"
> > @@ -324,21 +325,7 @@ static void gen_firmware(uint32_t *p, hwaddr kernel_entry, 
> > hwaddr fdt_addr,
> >        * a2/$6 = 0
> >        * a3/$7 = 0
> >        */
> > -    stl_p(p++, 0x2404fffe);                     /* li   $4, -2 */
> > -                                                /* lui  $5, hi(fdt_addr) */
> > -    stl_p(p++, 0x3c050000 | ((fdt_addr >> 16) & 0xffff));
> > -    if (fdt_addr & 0xffff) {                    /* ori  $5, lo(fdt_addr) */
> > -        stl_p(p++, 0x34a50000 | (fdt_addr & 0xffff));
> > -    }
> > -    stl_p(p++, 0x34060000);                     /* li   $6, 0 */
> > -    stl_p(p++, 0x34070000);                     /* li   $7, 0 */
> > -
> > -    /* Load kernel entry address & jump to it */
> > -                                                /* lui  $25, hi(kernel_entry) 
> > */
> > -    stl_p(p++, 0x3c190000 | ((kernel_entry >> 16) & 0xffff));
> > -                                                /* ori  $25, lo(kernel_entry) 
> > */
> > -    stl_p(p++, 0x37390000 | (kernel_entry & 0xffff));
> > -    stl_p(p++, 0x03200009);                     /* jr   $25 */
> Eh, no delay slot NOP :)
>
> > +    bl_gen_jump_kernel(&p, 0, (int32_t)-2, fdt_addr, 0, 0, kernel_entry);
> >   }
> >   
> ...
>
> > diff --git a/hw/mips/malta.c b/hw/mips/malta.c
> > index 9afc0b427b..ffd67b8293 100644
> > --- a/hw/mips/malta.c
> > +++ b/hw/mips/malta.c
> > @@ -37,6 +37,7 @@
> >   #include "hw/i2c/smbus_eeprom.h"
> >   #include "hw/block/flash.h"
> >   #include "hw/mips/mips.h"
> > +#include "hw/mips/bootloader.h"
> >   #include "hw/mips/cpudevs.h"
> >   #include "hw/pci/pci.h"
> >   #include "sysemu/sysemu.h"
> > @@ -844,6 +845,7 @@ static void write_bootloader_nanomips(uint8_t *base, 
> > uint64_t run_addr,
> >   static void write_bootloader(uint8_t *base, uint64_t run_addr,
> >                                uint64_t kernel_entry)
> >   {
> > +    target_ulong a0;
> >       uint32_t *p;
> >   
> >       /* Small bootloader */
> > @@ -872,30 +874,6 @@ static void write_bootloader(uint8_t *base, uint64_t 
> > run_addr,
> >       /* Second part of the bootloader */
> >       p = (uint32_t *) (base + 0x580);
> >   
> > -    if (semihosting_get_argc()) {
> > -        /* Preserve a0 content as arguments have been passed */
> > -        stl_p(p++, 0x00000000);              /* nop */
> > -    } else {
> > -        stl_p(p++, 0x24040002);              /* addiu a0, zero, 2 */
> > -    }
> > -
> > -    /* lui sp, high(ENVP_VADDR) */
> > -    stl_p(p++, 0x3c1d0000 | (((ENVP_VADDR - 64) >> 16) & 0xffff));
> > -    /* ori sp, sp, low(ENVP_VADDR) */
> > -    stl_p(p++, 0x37bd0000 | ((ENVP_VADDR - 64) & 0xffff));
> > -    /* lui a1, high(ENVP_VADDR) */
> > -    stl_p(p++, 0x3c050000 | ((ENVP_VADDR >> 16) & 0xffff));
> > -    /* ori a1, a1, low(ENVP_VADDR) */
> > -    stl_p(p++, 0x34a50000 | (ENVP_VADDR & 0xffff));
> > -    /* lui a2, high(ENVP_VADDR + 8) */
> > -    stl_p(p++, 0x3c060000 | (((ENVP_VADDR + 8) >> 16) & 0xffff));
> > -    /* ori a2, a2, low(ENVP_VADDR + 8) */
> > -    stl_p(p++, 0x34c60000 | ((ENVP_VADDR + 8) & 0xffff));
> > -    /* lui a3, high(ram_low_size) */
> > -    stl_p(p++, 0x3c070000 | (loaderparams.ram_low_size >> 16));
> > -    /* ori a3, a3, low(ram_low_size) */
> > -    stl_p(p++, 0x34e70000 | (loaderparams.ram_low_size & 0xffff));
> > -
> >       /* Load BAR registers as done by YAMON */
> >       stl_p(p++, 0x3c09b400);                  /* lui t1, 0xb400 */
> >   
> > @@ -947,13 +925,14 @@ static void write_bootloader(uint8_t *base, uint64_t run_addr,
> >   #endif
> >       stl_p(p++, 0xad280088);                  /* sw t0, 0x0088(t1) */
> >   
> > -    /* Jump to kernel code */
> > -    stl_p(p++, 0x3c1f0000 |
> > -          ((kernel_entry >> 16) & 0xffff));  /* lui ra, high(kernel_entry) */
> > -    stl_p(p++, 0x37ff0000 |
> > -          (kernel_entry & 0xffff));          /* ori ra, ra, low(kernel_entry) 
> > */
> > -    stl_p(p++, 0x03e00009);                  /* jalr ra */
> > -    stl_p(p++, 0x00000000);                  /* nop */
> > +    if (semihosting_get_argc()) {
> > +        a0 = 0;
> I never used semihosting with Malta, but it seems you are
> clearing $a0 content.

That's what original code did.
I guess when semihosting is enabled, arguments are going to be
passed by semi-syscall instead of boot registers?

Thanks.

- Jiaxun

> > +    } else {
> > +        a0 = 2;
> > +    }
> > +    bl_gen_jump_kernel(&p, ENVP_VADDR - 64, a0, ENVP_VADDR,
> > +                       ENVP_VADDR + 8, loaderparams.ram_low_size,
> > +                       kernel_entry);
> >   
> >       /* YAMON subroutines */
> >       p = (uint32_t *) (base + 0x800);