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// SPDX-License-Identifier: GPL-2.0
#include <linux/compat.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/perf_event.h>
#include <linux/bug.h>
#include <linux/sched/task_stack.h>
#include <asm/perf_regs.h>
#include <asm/ptrace.h>
u64 perf_reg_value(struct pt_regs *regs, int idx)
{
if (WARN_ON_ONCE((u32)idx >= PERF_REG_ARM64_MAX))
return 0;
/*
* Our handling of compat tasks (PERF_SAMPLE_REGS_ABI_32) is weird, but
* we're stuck with it for ABI compatibility reasons.
*
* For a 32-bit consumer inspecting a 32-bit task, then it will look at
* the first 16 registers (see arch/arm/include/uapi/asm/perf_regs.h).
* These correspond directly to a prefix of the registers saved in our
* 'struct pt_regs', with the exception of the PC, so we copy that down
* (x15 corresponds to SP_hyp in the architecture).
*
* So far, so good.
*
* The oddity arises when a 64-bit consumer looks at a 32-bit task and
* asks for registers beyond PERF_REG_ARM_MAX. In this case, we return
* SP_usr, LR_usr and PC in the positions where the AArch64 SP, LR and
* PC registers would normally live. The initial idea was to allow a
* 64-bit unwinder to unwind a 32-bit task and, although it's not clear
* how well that works in practice, somebody might be relying on it.
*
* At the time we make a sample, we don't know whether the consumer is
* 32-bit or 64-bit, so we have to cater for both possibilities.
*/
if (compat_user_mode(regs)) {
if ((u32)idx == PERF_REG_ARM64_SP)
return regs->compat_sp;
if ((u32)idx == PERF_REG_ARM64_LR)
return regs->compat_lr;
if (idx == 15)
return regs->pc;
}
if ((u32)idx == PERF_REG_ARM64_SP)
return regs->sp;
if ((u32)idx == PERF_REG_ARM64_PC)
return regs->pc;
return regs->regs[idx];
}
#define REG_RESERVED (~((1ULL << PERF_REG_ARM64_MAX) - 1))
int perf_reg_validate(u64 mask)
{
if (!mask || mask & REG_RESERVED)
return -EINVAL;
return 0;
}
u64 perf_reg_abi(struct task_struct *task)
{
if (is_compat_thread(task_thread_info(task)))
return PERF_SAMPLE_REGS_ABI_32;
else
return PERF_SAMPLE_REGS_ABI_64;
}
void perf_get_regs_user(struct perf_regs *regs_user,
struct pt_regs *regs)
{
regs_user->regs = task_pt_regs(current);
regs_user->abi = perf_reg_abi(current);
}
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