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riscv: add icache flush for nommu sigreturn trampoline

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In a NOMMU kernel, sigreturn trampolines are generated on the user
stack by setup_rt_frame. Currently, these trampolines are not instruction
fenced, thus their visibility to ifetch is not guaranteed.

This patch adds a flush_icache_range in setup_rt_frame to fix this
problem.

Signed-off-by: Mathis Salmen <mathis.salmen@matsal.de>
Fixes: 6bd33e1ece ("riscv: add nommu support")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230406101130.82304-1-mathis.salmen@matsal.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Mathis Salmen 2023-04-06 12:11:31 +02:00 committed by Palmer Dabbelt
parent 4622f15909
commit 8d73648274
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1 changed files with 8 additions and 1 deletions
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9
arch/riscv/kernel/signal.c
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@ -19,6 +19,7 @@
#include <asm/signal32.h>
#include <asm/switch_to.h>
#include <asm/csr.h>
#include <asm/cacheflush.h>
extern u32 __user_rt_sigreturn[2];
@ -181,6 +182,7 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
{
struct rt_sigframe __user *frame;
long err = 0;
unsigned long __maybe_unused addr;
frame = get_sigframe(ksig, regs, sizeof(*frame));
if (!access_ok(frame, sizeof(*frame)))
@ -209,7 +211,12 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
if (copy_to_user(&frame->sigreturn_code, __user_rt_sigreturn,
sizeof(frame->sigreturn_code)))
return -EFAULT;
regs->ra = (unsigned long)&frame->sigreturn_code;
addr = (unsigned long)&frame->sigreturn_code;
/* Make sure the two instructions are pushed to icache. */
flush_icache_range(addr, addr + sizeof(frame->sigreturn_code));
regs->ra = addr;
#endif /* CONFIG_MMU */
/*