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arm64: Fix relocation of env_addr if POSITION_INDEPENDENT=y

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If both POSITION_INDEPENDENT and SYS_RELOC_GD_ENV_ADDR are enabled,
wherever original env is placed anywhere, it should be relocated to
the right address.

Relocation offset gd->reloc_off is calculated with SYS_TEXT_BASE in
setup_reloc() and env address gd->env_addr is relocated by the offset in
initr_reloc_global_data().

gd->env_addr
  = (orig env) + gd->reloc_off
  = (orig env) + (gd->relocaddr - SYS_TEXT_BASE)

However, SYS_TEXT_BASE isn't always runtime base address when
POSITION_INDEPENDENT is enabled. So the relocated env_addr might point to
wrong address. For example, if SYS_TEXT_BASE is zero, gd->env_addr is
out of memory location and memory exception will occur.

There is a difference between linked address such as SYS_TEXT_BASE and
runtime base address. In _main, the difference is calculated as
"run-vs-link" offset. The env_addr should also be added to the offset
to fix the address.

gd->env_addr
  = (orig env) + ("run-vs-link" offset)   + gd->reloc_off
  = (orig env) + (SYS_TEXT_BASE - _start) + (gd->relocaddr - SYS_TEXT_BASE)
  = (orig env) + (gd->relocaddr - _start)

Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Acked-by: Marek Vasut <marex@denx.de>
Tested-by: Marek Vasut <marex@denx.de>
This commit is contained in:
Kunihiko Hayashi 2021-06-15 15:33:02 +09:00 committed by Tom Rini
parent 2bba78076b
commit 534f0fbd65
2 changed files with 7 additions and 0 deletions
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5
arch/arm/lib/crt0_64.S
View File

@ -112,6 +112,11 @@ ENTRY(_main)
ldr x9, _TEXT_BASE /* x9 <- Linked value of _start */
sub x9, x9, x0 /* x9 <- Run-vs-link offset */
add lr, lr, x9
#if defined(CONFIG_SYS_RELOC_GD_ENV_ADDR)
ldr x0, [x18, #GD_ENV_ADDR] /* x0 <- gd->env_addr */
add x0, x0, x9
str x0, [x18, #GD_ENV_ADDR]
#endif
#endif
/* Add in link-vs-relocation offset */
ldr x9, [x18, #GD_RELOC_OFF] /* x9 <- gd->reloc_off */

2
lib/asm-offsets.c
View File

@ -41,5 +41,7 @@ int main(void)
DEFINE(GD_NEW_GD, offsetof(struct global_data, new_gd));
DEFINE(GD_ENV_ADDR, offsetof(struct global_data, env_addr));
return 0;
}