Unverified Commit e609b4f4 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Palmer Dabbelt
Browse files

riscv: Move global pointer loading to a macro 

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: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a484e843e6eeb51f0cb7b8819e50da6d2444d769


Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Tested-by: default avatarNathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20230927224757.1154247-11-samitolvanen@google.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 82982fdd

arch/riscv/include/asm/asm.h

+8 −0
Original line number Diff line number Diff line
@@ -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)

arch/riscv/kernel/entry.S

+2 −4
Original line number Diff line number Diff line
@@ -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

arch/riscv/kernel/head.S

+3 −12
Original line number Diff line number Diff line
@@ -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

arch/riscv/kernel/suspend_entry.S

+1 −4
Original line number Diff line number Diff line
@@ -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 */