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riscv: Move global pointer loading to a macro

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In Clang 17, -fsanitize=shadow-call-stack uses the newly declared
platform register gp for storing shadow call stack pointers. As
this is obviously incompatible with gp relaxation, in preparation
for CONFIG_SHADOW_CALL_STACK support, move global pointer loading
to a single macro, which we can cleanly disable when SCS is used
instead.

Link: https://reviews.llvm.org/rGaa1d2693c256
Link: a484e843e6
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230927224757.1154247-11-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Sami Tolvanen 2023-09-27 22:48:01 +00:00 committed by Palmer Dabbelt
parent 82982fdd51
commit e609b4f425
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4 changed files with 14 additions and 20 deletions
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8
arch/riscv/include/asm/asm.h
View File

@ -109,6 +109,14 @@
REG_L \dst, 0(\dst)
.endm
/* load __global_pointer to gp */
.macro load_global_pointer
.option push
.option norelax
la gp, __global_pointer$
.option pop
.endm
/* save all GPs except x1 ~ x5 */
.macro save_from_x6_to_x31
REG_S x6, PT_T1(sp)

6
arch/riscv/kernel/entry.S
View File

@ -75,10 +75,8 @@ _save_context:
csrw CSR_SCRATCH, x0
/* Load the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
load_global_pointer
move a0, sp /* pt_regs */
la ra, ret_from_exception

15
arch/riscv/kernel/head.S
View File

@ -110,10 +110,7 @@ relocate_enable_mmu:
csrw CSR_TVEC, a0
/* Reload the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
load_global_pointer
/*
* Switch to kernel page tables. A full fence is necessary in order to
@ -134,10 +131,7 @@ secondary_start_sbi:
csrw CSR_IP, zero
/* Load the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
load_global_pointer
/*
* Disable FPU & VECTOR to detect illegal usage of
@ -228,10 +222,7 @@ pmp_done:
#endif /* CONFIG_RISCV_M_MODE */
/* Load the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
load_global_pointer
/*
* Disable FPU & VECTOR to detect illegal usage of

5
arch/riscv/kernel/suspend_entry.S
View File

@ -61,10 +61,7 @@ END(__cpu_suspend_enter)
SYM_TYPED_FUNC_START(__cpu_resume_enter)
/* Load the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
load_global_pointer
#ifdef CONFIG_MMU
/* Save A0 and A1 */