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| author | Vincent Chen <vincent.chen@sifive.com> | 2023-06-05 14:07:12 +0300 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-06-08 17:16:48 +0300 |
| commit | e92f469b0771e6db9688a58c0e34a8342da6a6bc (patch) | |
| tree | 558ccc36a1d7a0584726c3722c79874ad144820e /arch/riscv/include | |
| parent | 8ee0b41898fa26f66e32237f179b6989c65600d6 (diff) | |
| download | linux-e92f469b0771e6db9688a58c0e34a8342da6a6bc.tar.xz | |
riscv: signal: Report signal frame size to userspace via auxv
The vector register belongs to the signal context. They need to be stored
and restored as entering and leaving the signal handler. According to the
V-extension specification, the maximum length of the vector registers can
be 2^16. Hence, if userspace refers to the MINSIGSTKSZ to create a
sigframe, it may not be enough. To resolve this problem, this patch refers
to the commit 94b07c1f8c39c
("arm64: signal: Report signal frame size to userspace via auxv") to enable
userspace to know the minimum required sigframe size through the auxiliary
vector and use it to allocate enough memory for signal context.
Note that auxv always reports size of the sigframe as if V exists for
all starting processes, whenever the kernel has CONFIG_RISCV_ISA_V. The
reason is that users usually reference this value to allocate an
alternative signal stack, and the user may use V anytime. So the user
must reserve a space for V-context in sigframe in case that the signal
handler invokes after the kernel allocating V.
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Tested-by: Heiko Stuebner <heiko.stuebner@vrull.eu>
Link: https://lore.kernel.org/r/20230605110724.21391-16-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/include')
| -rw-r--r-- | arch/riscv/include/asm/elf.h | 9 | ||||
| -rw-r--r-- | arch/riscv/include/asm/processor.h | 2 | ||||
| -rw-r--r-- | arch/riscv/include/uapi/asm/auxvec.h | 1 |
3 files changed, 12 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h index 30e7d2455960..ca23c4f6c440 100644 --- a/arch/riscv/include/asm/elf.h +++ b/arch/riscv/include/asm/elf.h @@ -105,6 +105,15 @@ do { \ get_cache_size(3, CACHE_TYPE_UNIFIED)); \ NEW_AUX_ENT(AT_L3_CACHEGEOMETRY, \ get_cache_geometry(3, CACHE_TYPE_UNIFIED)); \ + /* \ + * Should always be nonzero unless there's a kernel bug. \ + * If we haven't determined a sensible value to give to \ + * userspace, omit the entry: \ + */ \ + if (likely(signal_minsigstksz)) \ + NEW_AUX_ENT(AT_MINSIGSTKSZ, signal_minsigstksz); \ + else \ + NEW_AUX_ENT(AT_IGNORE, 0); \ } while (0) #define ARCH_HAS_SETUP_ADDITIONAL_PAGES struct linux_binprm; diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index f0ddf691ac5e..38ded8c5f207 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -7,6 +7,7 @@ #define _ASM_RISCV_PROCESSOR_H #include <linux/const.h> +#include <linux/cache.h> #include <vdso/processor.h> @@ -81,6 +82,7 @@ int riscv_of_parent_hartid(struct device_node *node, unsigned long *hartid); extern void riscv_fill_hwcap(void); extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); +extern unsigned long signal_minsigstksz __ro_after_init; #endif /* __ASSEMBLY__ */ #endif /* _ASM_RISCV_PROCESSOR_H */ diff --git a/arch/riscv/include/uapi/asm/auxvec.h b/arch/riscv/include/uapi/asm/auxvec.h index fb187a33ce58..10aaa83db89e 100644 --- a/arch/riscv/include/uapi/asm/auxvec.h +++ b/arch/riscv/include/uapi/asm/auxvec.h @@ -35,5 +35,6 @@ /* entries in ARCH_DLINFO */ #define AT_VECTOR_SIZE_ARCH 9 +#define AT_MINSIGSTKSZ 51 #endif /* _UAPI_ASM_RISCV_AUXVEC_H */ |