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| author | Bo Gan <ganboing@gmail.com> | 2025-12-15 21:25:28 -0800 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2025-12-27 11:21:27 +0530 |
| commit | 4c1c77e085599f6f95df4b94714e1d7829ebefbf (patch) | |
| tree | 26d4b8196d334bb2373b92177ec646a281d3be5a /include | |
| parent | f7b81034aa4c19199afac6be4e033270f3755bf5 (diff) | |
| download | opensbi-4c1c77e085599f6f95df4b94714e1d7829ebefbf.zip opensbi-4c1c77e085599f6f95df4b94714e1d7829ebefbf.tar.gz opensbi-4c1c77e085599f6f95df4b94714e1d7829ebefbf.tar.bz2 | |
include: riscv_asm: Optimize csr_xyz() macros to reduce stack usage
When using debug builds, aka., DEBUG=1, csr_write_num() function can
trigger stack overflow. This is caused by the large amount of macro
expansion of csr_write(...), which, under debug builds, will generate
massive amount of stack variables (tested with GCC 13.2.0). The issue
is masked previously as we didn't have too many csr_write()'s before
commit 55296fd27c0c, but now, it does overflow the default 4KB stack.
The csr_read(relaxed) macros already use the "register" modifier to
optimize stack usage (perhaps unknowingly?), so this patch just
follows suit.
Fixes: 55296fd27c0c ("lib: Allow custom CSRs in csr_read_num() and csr_write_num()")
Signed-off-by: Bo Gan <ganboing@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251216052528.18896-1-ganboing@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/sbi/riscv_asm.h | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h index ef48dc8..0cf3fc3 100644 --- a/include/sbi/riscv_asm.h +++ b/include/sbi/riscv_asm.h @@ -83,7 +83,7 @@ #define csr_swap(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrrw %0, " __ASM_STR(csr) ", %1" \ : "=r"(__v) \ : "rK"(__v) \ @@ -111,7 +111,7 @@ #define csr_write(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrw " __ASM_STR(csr) ", %0" \ : \ : "rK"(__v) \ @@ -120,7 +120,7 @@ #define csr_read_set(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrrs %0, " __ASM_STR(csr) ", %1" \ : "=r"(__v) \ : "rK"(__v) \ @@ -130,7 +130,7 @@ #define csr_set(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrs " __ASM_STR(csr) ", %0" \ : \ : "rK"(__v) \ @@ -139,7 +139,7 @@ #define csr_read_clear(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrrc %0, " __ASM_STR(csr) ", %1" \ : "=r"(__v) \ : "rK"(__v) \ @@ -149,7 +149,7 @@ #define csr_clear(csr, val) \ ({ \ - unsigned long __v = (unsigned long)(val); \ + register unsigned long __v = (unsigned long)(val); \ __asm__ __volatile__("csrc " __ASM_STR(csr) ", %0" \ : \ : "rK"(__v) \ |